Fixed a perhaps rare crash during rate testing. (#367)

* Add --socks argument for scanning via SOCKS5 proxy

Implement SOCKS5 proxy support without external dependencies:
- Add socks_proxy field to AuditConf
- Add --socks host:port CLI argument with input validation
- Implement SOCKS5 handshake (no-auth, domain-name addressing) in
  SSH_Socket._connect_via_socks5()

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Michał Majchrowicz <sectroyer@gmail.com>

* Add SOCKS proxy regression tests

---------

Signed-off-by: Michał Majchrowicz <sectroyer@gmail.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

PACKAGING.md

@@ -18,7 +18,7 @@ An executable can only be made on a Windows host because the PyInstaller tool (h
 To create package and upload to test server (hint: use API token for test.pypi.org):
 
 ```
-    $ sudo apt install python3-virtualenv python3.12-venv
+    $ sudo apt install python3-virtualenv python3.14-venv
     $ make -f Makefile.pypi
     $ make -f Makefile.pypi uploadtest
 ```
@@ -48,7 +48,7 @@ To download from production server and verify:
 
 # Snap
 
-To create the Snap package, run a fully-updated Ubuntu Server 24.04 VM.
+To create the Snap package, run a fully-updated Ubuntu Server 26.04 VM.
 
 Create the Snap package with:
 ```
@@ -68,9 +68,17 @@ Upload the Snap with:
 
 # Docker
 
-Ensure that the `buildx` plugin is available by following the installation instructions available at: https://docs.docker.com/engine/install/ubuntu/
+On an Ubuntu Server 26.06 VM, install dependencies with:
+```
+    # apt install docker.io docker-buildx
+```
 
-Build a local image with:
+Ensure that your non-root build user can access the docker daemon with by adding it to the `docker` group:
+```
+    # usermod -a -G docker build_user
+```
+
+As a non-root user, build a local image with:
 
 ```
     $ make -f Makefile.docker

README.md

@@ -48,10 +48,10 @@ usage: ssh-audit.py [-h] [-4] [-6] [-b] [-c] [-d]
                     [--conn-rate-test N[:max_rate]] [--dheat N[:kex[:e_len]]]
                     [--get-hardening-guide platform] [--list-hardening-guides]
                     [--lookup alg1[,alg2,...]] [--skip-rate-test]
-                    [--threads N]
+                    [--socks5 host:port] [--threads N]
                     [host]
 
-# ssh-audit.py v3.4.0-dev, https://github.com/jtesta/ssh-audit
+# ssh-audit.py v3.4.1-dev, https://github.com/jtesta/ssh-audit
 
 positional arguments:
   host                  target hostname or IPv4/IPv6 address
@@ -93,7 +93,8 @@ optional arguments:
                         used)
   -T targets.txt, --targets targets.txt
                         a file containing a list of target hosts (one per
-                        line, format HOST[:PORT]). Use -p/--port to set the
+                        line, format 'HOST[:PORT]'; for UNIX socket servers,
+                        use 'unix:///path/socket'). Use -p/--port to set the
                         default port for all hosts. Use --threads to control
                         concurrent scans
   -t N, --timeout N     timeout (in seconds) for connection and reading
@@ -127,6 +128,7 @@ optional arguments:
   --skip-rate-test      skip the connection rate test during standard audits
                         (used to safely infer whether the DHEat attack is
                         viable)
+  --socks5 host:port    connect via a SOCKS5 proxy (implies --skip-rate-test)
   --threads N           number of threads to use when scanning multiple
                         targets (-T/--targets) (default: 32)
 ```
@@ -142,6 +144,7 @@ ssh-audit 127.0.0.1
 ssh-audit 127.0.0.1:222
 ssh-audit ::1
 ssh-audit [::1]:222
+ssh-audit unix:///run/ssh-unix-local/socket
 ```
 
 To run a standard audit against many servers (place targets into servers.txt, one on each line in the format of `HOST[:PORT]`):
@@ -150,13 +153,13 @@ To run a standard audit against many servers (place targets into servers.txt, on
 ssh-audit -T servers.txt
 ```
 
-To audit a client configuration (listens on port 2222 by default; connect using `ssh -p 2222 anything@localhost`):
+To audit a client configuration (listens on port 2222/tcp by default; connect using `ssh -p 2222 anything@localhost`):
 
 ```
 ssh-audit -c
 ```
 
-To audit a client configuration, with a listener on port 4567:
+To audit a client configuration, with a listener on port 4567/tcp:
 ```
 ssh-audit -c -p 4567
 ```
@@ -236,9 +239,9 @@ $ snap install ssh-audit
 
 To install from Dockerhub:
 ```
-$ docker pull positronsecurity/ssh-audit
+$ docker pull docker.io/positronsecurity/ssh-audit
 ```
-(Then run with: `docker run -it --rm -p 2222:2222 positronsecurity/ssh-audit 10.1.1.1`)
+(Then run with: `docker run -it --rm -p 2222:2222 docker.io/positronsecurity/ssh-audit 10.1.1.1`)
 
 The status of various other platform packages can be found below (via Repology):
 
@@ -249,8 +252,12 @@ For convenience, a web front-end on top of the command-line tool is available at
 
 ## ChangeLog
 
-### v3.4.0-dev
+### v3.9.1-dev
+ - Fixed a perhaps rare crash when performing connection rate tests during standard audits.
+
+### v3.9.0 (2026-07-04)
  - BIG THANKS to [realmiwi](https://github.com/realmiwi) for being the project's *very first sponsor!!*
+ - Added support for Python 3.14.
  - Dropped support for Python 3.8, as it reached end-of-life in October 2024.
  - Dropped support for Python 3.9, as it reached end-of-life in October 2025.
  - Added warning to all key exchanges that do not include protections against quantum attacks due to the Harvest Now, Decrypt Later strategy (see https://en.wikipedia.org/wiki/Harvest_now,_decrypt_later).
@@ -260,10 +267,15 @@ For convenience, a web front-end on top of the command-line tool is available at
  - Migrated from deprecated `getopt` module to `argparse`; partial credit [oam7575](https://github.com/oam7575).
  - When running against multiple hosts, now prints each target host regardless of output level.
  - Batch mode (`-b`) no longer automatically enables verbose mode, due to sometimes confusing results; users can still explicitly enable verbose mode using the `-v` flag.
- - Added built-in policy for OpenSSH 10.0.
+ - Added UNIX server socket scanning (specify the target with `unix:///path/to/socket`).
+ - Added SOCKS5 proxy support (specify the proxy with `--socks5 host:port`); partial credit [Michał Majchrowicz](https://github.com/sectroyer).
+ - Updated built-in policy for Debian 12.
+ - Added built-in policies for OpenSSH 10.0, 10.1, 10.2, 10.3, and 10.4.
  - Added hardening guides and policies for Debian 13.
+ - Added hardening guides and policies for Rocky Linux 10.
+ - Added hardening guides and policies for Ubuntu 26.04.
  - Added 2 new key exchanges: `mlkem768nistp256-sha256`, `mlkem1024nistp384-sha384`.
- - Added 1 new host key: `webauthn-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com`.
+ - Added 11 new host keys: `webauthn-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com`, `mldsa-44`, `ssh-mldsa44-ed25519@openssh.com`, `mldsa-65`, `mldsa-87`, `ssh-mldsa-44`, `ssh-mldsa-65`, `ssh-mldsa-87`, `ssh-mldsa44`, `ssh-mldsa65`, `ssh-mldsa87`.
  - Added 2 new ciphers: `AEAD_CAMELLIA_128_GCM`, `AEAD_CAMELLIA_256_GCM`.
 
 ### v3.3.0 (2024-10-15)

build_snap.sh

@@ -3,7 +3,7 @@
 #
 #   The MIT License (MIT)
 #
-#   Copyright (C) 2021-2024 Joe Testa (jtesta@positronsecurity.com)
+#   Copyright (C) 2021-2026 Joe Testa (jtesta@positronsecurity.com)
 #
 #   Permission is hereby granted, free of charge, to any person obtaining a copy
 #   of this software and associated documentation files (the "Software"), to deal
@@ -32,19 +32,23 @@
 
 
 # Pre-requisites
+echo "Installing pre-requisites..."
 sudo apt install -y make
 sudo snap install snapcraft --classic
 sudo snap install review-tools lxd
 
 # Initialize LXD.
+echo -e "\nInitializing LXD..."
 sudo lxd init --auto
 
-# Reset the filesystem from any previous runs.
-rm -rf parts/ prime/ snap/ stage/ build/ dist/ src/*.egg-info/ ssh-audit*.snap
+# Reset local files that may have been changed through a previous run.
+echo "Resetting local files..."
+rm -f ssh-audit*.snap
 git checkout snapcraft.yaml 2> /dev/null
 git checkout src/ssh_audit/globals.py 2> /dev/null
 
 # Add the built-in manual page.
+echo "Processing man page..."
 ./add_builtin_man_page.sh
 
 # Get the version from the globals.py file.
@@ -67,10 +71,41 @@ if [[ ! $snap_version =~ ^[0-9]\.[0-9]\.[0-9]\-[0-9]$ ]]; then
    exit 1
 fi
 
-# Append the version field to the end of the file.  Not pretty, but it works.
-echo -e "\nversion: '${snap_version}'" >> snapcraft.yaml
+# Set the version field.
+sed -i "s/version: \"\"/version: \"${snap_version}\"/" snapcraft.yaml
+
+# Ensure we set the version field correctly.
+grep "version: \"${snap_version}\"" snapcraft.yaml > /dev/null 2> /dev/null
+if [[ $? != 0 ]]; then
+    echo "Failed to set version field in snapcraft.yaml."
+    exit 1
+fi
 
 # Set the SNAP_PACKAGE variable to True so that file permission errors give more user-friendly 
 sed -i 's/SNAP_PACKAGE = False/SNAP_PACKAGE = True/' src/ssh_audit/globals.py
 
-snapcraft --use-lxd && echo -e "\nDone.\n"
+# Clean any previous builds.
+echo "Running 'snapcraft clean'..."
+snapcraft clean
+
+# Build the snap file.
+echo "Running 'snapcraft pack --use-lxd'..."
+snapcraft pack --use-lxd
+if [[ $? != 0 ]]; then
+    echo -e "\nPack process failed: $?"
+    exit 1
+else
+    echo -e "Pack process succeeded."
+fi
+
+# Run the linter on it.
+echo "Running 'snapcraft lint' on *.snap..."
+snapcraft lint --quiet *.snap
+if [[ $? != 0 ]]; then
+    echo -e "\nLint process failed: $?"
+    exit 1
+else
+    echo -e "Lint process succeeded."
+fi
+
+echo -e "\nDone!\n"

docker_test.sh

@@ -23,7 +23,7 @@
 IMAGE_VERSION=3
 
 # This is the name of our docker image.
-IMAGE_NAME=positronsecurity/ssh-audit-test-framework
+IMAGE_NAME=docker.io/positronsecurity/ssh-audit-test-framework
 
 
 # Terminal colors.

snapcraft.yaml

@@ -1,23 +1,34 @@
 name: ssh-audit
-# 'version' field will be automatically added by build_snap.sh.
-license: 'MIT'
+title: ssh-audit
 summary: ssh-audit
+version: ""  # Set at run-time by build_snap.sh.
+license: 'MIT'
 description: |
   SSH server and client security configuration auditor.  Official repository: <https://github.com/jtesta/ssh-audit>
-
-base: core22
+contact:
+  - https://github.com/jtesta/ssh-audit/issues
+issues:
+  - https://github.com/jtesta/ssh-audit/issues
+source-code:
+  - https://github.com/jtesta/ssh-audit
+website:
+  - https://github.com/jtesta/ssh-audit
+#base: core26
+base: core24
 grade: stable
 confinement: strict
-architectures:
-  - build-on: [amd64]
+platforms:
+  multi:
+    build-on: [amd64]
     build-for: [all]
 
 apps:
   ssh-audit:
     command: bin/ssh-audit
-    plugs: [network,network-bind,home]
+    plugs: [network, network-bind, home]
 
 parts:
   ssh-audit:
     plugin: python
+    #stage-packages: [python3.14, python3.14-venv]
     source: .

src/ssh_audit/algorithms.py

@@ -117,8 +117,6 @@ class Algorithms:
             sshv, alg_db = alg_pair.sshv, alg_pair.db
             rec[sshv] = {}
             for alg_type, alg_list in alg_pair.items():
-                if alg_type == 'aut':
-                    continue
                 rec[sshv][alg_type] = {'add': {}, 'del': {}, 'chg': {}}
                 for n, alg_desc in alg_db[alg_type].items():
                     versions = alg_desc[0]

src/ssh_audit/auditconf.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2017-2025 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017-2026 Joe Testa (jtesta@positronsecurity.com)
    Copyright (C) 2017 Andris Raugulis (moo@arthepsy.eu)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -67,6 +67,7 @@ class AuditConf:
         self.conn_rate_test_enabled = False
         self.conn_rate_test_threads = 0
         self.conn_rate_test_target_rate = 0
+        self.socks5_proxy: Optional[str] = None  # SOCKS5 proxy in "host:port" format
 
 
     def __setattr__(self, name: str, value: Union[str, int, float, bool, Sequence[int]]) -> None:
@@ -185,6 +186,12 @@ class AuditConf:
             if not isinstance(value, int):
                 valid = False
 
+        elif name == "socks5_proxy":
+            valid = True
+            if isinstance(value, str):
+                host, port = Utils.parse_host_and_port(value, 0)
+                if len(host) == 0 or port <= 0 or port >= 65535:
+                    raise ValueError("SOCKS5 host must be in host:port format.")
 
         if valid:
             object.__setattr__(self, name, value)

src/ssh_audit/builtin_policies.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2020-2024 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2020-2026 Joe Testa (jtesta@positronsecurity.com)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
@@ -38,14 +38,18 @@ BUILTIN_POLICIES: Dict[str, Dict[str, Union[Optional[str], Optional[List[str]],
 
     'Hardened Debian 12 (version 2)': {'version': '2', 'changelog': 'Re-ordered host keys to prioritize ED25519 due to efficiency.  Re-ordered cipher list to prioritize larger key sizes as a countermeasure to quantum attacks.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
 
+    'Hardened Debian 12 (version 3)': {'version': '3', 'changelog': 'Added sntrup761x25519-sha512 key exchange.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
+
     'Hardened Debian 13 (version 1)': {'version': '1', 'changelog': 'Initial revision.  As compared to the Debian 12 guide, the following changes were made: 1.) all non-post-quantum key exchanges were removed, and mlkem768x25519-sha256 and sntrup761x25519-sha512 were added, 2.) editing the /etc/ssh/moduli file is no longer done, as we no longer use any group-exchange algorithms (none of them currently protect against quantum attacks), 3.) editing the sshd_config file is no longer done, in order to make system upgrades easier for users, 4.) network-level connection throttling is no longer done, as OpenSSH prevents the DHEat attack by default now.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, "allow_hostkey_subset_and_reordering": True, 'server_policy': True},
 
 
-    # Rocky Linux 9
+    # Rocky Linux
     'Hardened Rocky Linux 9 (version 1)': {'version': '1', 'changelog': 'Initial version', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes128-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
 
     'Hardened Rocky Linux 9 (version 2)': {'version': '2', 'changelog': 'Re-ordered host keys to prioritize ED25519 due to efficiency.  Re-ordered cipher list to prioritize larger key sizes as a countermeasure to quantum attacks.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
 
+    'Hardened Rocky Linux 10 (version 1)': {'version': '1', 'changelog': 'Initial revision. In comparison to the Rocky Linux 9 hardening guide, the following changes were made: the key exchange list was set to include post-quantum algorithms only.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
+
 
     # Ubuntu Server policies
 
@@ -63,6 +67,8 @@ BUILTIN_POLICIES: Dict[str, Dict[str, Union[Optional[str], Optional[List[str]],
 
     'Hardened Ubuntu Server 24.04 LTS (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group16-sha512', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
 
+    'Hardened Ubuntu Server 26.04 LTS (version 1)': {'version': '1', 'changelog': 'Initial revision. As compared to the Ubuntu Server 24.04 guide, the following changes were made: 1.) all non-post-quantum key exchanges were removed, and mlkem768x25519-sha256 and sntrup761x25519-sha512 were added, 2.) editing the /etc/ssh/moduli file is no longer done, as we no longer use any group-exchange algorithms (none of them currently protect against quantum attacks), 3.) editing the sshd_config file is no longer done, in order to make system upgrades easier for users, 4.) network-level connection throttling is no longer done, as OpenSSH prevents the DHEat attack by default now.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, "allow_hostkey_subset_and_reordering": True, 'server_policy': True},
+
     # Generic OpenSSH Server policies
 
     'Hardened OpenSSH Server v7.7 (version 4)': {'version': '4', 'changelog': 'No change log available.', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes128-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {'diffie-hellman-group-exchange-sha256': 3072}, 'server_policy': True},
@@ -113,6 +119,16 @@ BUILTIN_POLICIES: Dict[str, Dict[str, Union[Optional[str], Optional[List[str]],
 
     'Hardened OpenSSH Server v10.0 (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {}, 'server_policy': True},
 
+    'Hardened OpenSSH Server v10.1 (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {}, 'server_policy': True},
+
+    'Hardened OpenSSH Server v10.2 (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {}, 'server_policy': True},
+
+    'Hardened OpenSSH Server v10.3 (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {}, 'server_policy': True},
+
+    # Note that the "ssh-mldsa44-ed25519@openssh.com" host key was added in this release as an experimental non-default option. Once it is no longer considered experimental by the OpenSSH developers, it will become a requirement.
+    'Hardened OpenSSH Server v10.4 (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-ed25519'], 'optional_host_keys': ['sk-ssh-ed25519@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'sk-ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com'], 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-s', 'kex-strict-s-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': {"rsa-sha2-256": {"hostkey_size": 4096}, "rsa-sha2-256-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "rsa-sha2-512": {"hostkey_size": 4096}, "rsa-sha2-512-cert-v01@openssh.com": {"ca_key_size": 4096, "ca_key_type": "ssh-rsa", "hostkey_size": 4096}, "sk-ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}, "sk-ssh-ed25519@openssh.com": {"hostkey_size": 256}, "ssh-ed25519": {"hostkey_size": 256}, "ssh-ed25519-cert-v01@openssh.com": {"ca_key_size": 256, "ca_key_type": "ssh-ed25519", "hostkey_size": 256}}, 'dh_modulus_sizes': {}, 'server_policy': True},
+
+
     # Amazon Linux Policies
 
     'Hardened Amazon Linux Client 2023 (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['sk-ssh-ed25519-cert-v01@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'sk-ssh-ed25519@openssh.com', 'ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': None, 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'ext-info-c', 'kex-strict-c-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes128-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': None, 'dh_modulus_sizes': None, 'server_policy': False},
@@ -135,6 +151,8 @@ BUILTIN_POLICIES: Dict[str, Dict[str, Union[Optional[str], Optional[List[str]],
 
     'Hardened Rocky Linux Client 9 (version 2)': {'version': '2', 'changelog': 'Re-ordered cipher list to prioritize larger key sizes as a countermeasure to quantum attacks.', 'banner': None, 'compressions': None, 'host_keys': ['sk-ssh-ed25519-cert-v01@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'sk-ssh-ed25519@openssh.com', 'ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': None, 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'ext-info-c', 'kex-strict-c-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': None, 'dh_modulus_sizes': None, 'server_policy': False},
 
+    'Hardened Rocky Linux Client 10 (version 1)': {'version': '1', 'changelog': 'Initial revision. In comparison to the Rocky Linux 9 hardening guide, the following changes were made: the key exchange list was set to include post-quantum algorithms only.', 'banner': None, 'compressions': None, 'host_keys': ['sk-ssh-ed25519-cert-v01@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'sk-ssh-ed25519@openssh.com', 'ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': None, 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-c', 'kex-strict-c-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': None, 'dh_modulus_sizes': None, 'server_policy': False},
+
     # Ubuntu Client policies
 
     'Hardened Ubuntu Client 16.04 LTS (version 2)': {'version': '2', 'changelog': 'No change log available.', 'banner': None, 'compressions': None, 'host_keys': ['ssh-ed25519', 'ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-256', 'rsa-sha2-512'], 'optional_host_keys': None, 'kex': ['curve25519-sha256@libssh.org', 'diffie-hellman-group-exchange-sha256', 'ext-info-c'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes128-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-ctr'], 'macs': ['hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': None, 'dh_modulus_sizes': None, 'server_policy': False},
@@ -149,4 +167,6 @@ BUILTIN_POLICIES: Dict[str, Dict[str, Union[Optional[str], Optional[List[str]],
 
     'Hardened Ubuntu Client 24.04 LTS (version 1)': {'version': '1', 'changelog': 'Initial version.', 'banner': None, 'compressions': None, 'host_keys': ['sk-ssh-ed25519-cert-v01@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'sk-ssh-ed25519@openssh.com', 'ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': None, 'kex': ['sntrup761x25519-sha512@openssh.com', 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group18-sha512', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group16-sha512', 'ext-info-c', 'kex-strict-c-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': None, 'dh_modulus_sizes': None, 'server_policy': False},
 
+    'Hardened Ubuntu Client 26.04 LTS (version 1)': {'version': '1', 'changelog': 'Initial revision.  As compared to the Ubuntu Client 24.04 guide, the following changes were made: all non-post-quantum key exchanges were removed, and mlkem768x25519-sha256 and sntrup761x25519-sha512 were added.', 'banner': None, 'compressions': None, 'host_keys': ['sk-ssh-ed25519-cert-v01@openssh.com', 'ssh-ed25519-cert-v01@openssh.com', 'rsa-sha2-512-cert-v01@openssh.com', 'rsa-sha2-256-cert-v01@openssh.com', 'sk-ssh-ed25519@openssh.com', 'ssh-ed25519', 'rsa-sha2-512', 'rsa-sha2-256'], 'optional_host_keys': None, 'kex': ['mlkem768x25519-sha256', 'sntrup761x25519-sha512', 'sntrup761x25519-sha512@openssh.com', 'ext-info-c', 'kex-strict-c-v00@openssh.com'], 'ciphers': ['chacha20-poly1305@openssh.com', 'aes256-gcm@openssh.com', 'aes256-ctr', 'aes192-ctr', 'aes128-gcm@openssh.com', 'aes128-ctr'], 'macs': ['hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'umac-128-etm@openssh.com'], 'hostkey_sizes': None, 'dh_modulus_sizes': None, 'server_policy': False},
+
 }

src/ssh_audit/dheat.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2023-2024 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2023-2026 Joe Testa (jtesta@positronsecurity.com)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
@@ -194,7 +194,9 @@ class DHEat:
         self.num_connect_timeouts = 0
         self.num_read_timeouts = 0
         self.num_socket_exceptions = 0
-        self.num_openssh_throttled_connections = 0
+        self.num_em = 0     # Number of "Exceeded MaxStartups" messages.
+        self.num_naatt = 0  # Number of "No allowed at this time" messages.
+        self.num_invalid_banners = 0
 
         # The time we started the attack.
         self.start_timer = 0.0
@@ -322,7 +324,11 @@ class DHEat:
             except OSError:
                 pass
 
-            del socket_dict[s]
+            if s in socket_dict:
+                del socket_dict[s]
+
+        # Check if this platform has socket.AF_UNIX. Windows does not.
+        has_af_unix = hasattr(socket, 'AF_UNIX')
 
         # Resolve the target into an IP address
         out.d("Resolving target %s..." % aconf.host)
@@ -351,10 +357,10 @@ class DHEat:
 
             rate_str = ""
             if aconf.conn_rate_test_target_rate > 0:
-                rate_str = " at a max rate of %s%u%s connections per second" % (DHEat.WHITEB, aconf.conn_rate_test_target_rate, DHEat.CLEAR)
+                rate_str = f" at a max rate of {DHEat.WHITEB}{aconf.conn_rate_test_target_rate:d}{DHEat.CLEAR} connections per second"
 
             print()
-            print("Performing non-disruptive rate test against %s[%s]:%u%s with %s%u%s concurrent sockets%s.  No Diffie-Hellman requests will be sent." % (DHEat.WHITEB, target_ip_address, aconf.port, DHEat.CLEAR, DHEat.WHITEB, concurrent_sockets, DHEat.CLEAR, rate_str))
+            print(f"Performing non-disruptive rate test against {DHEat.WHITEB}[{target_ip_address}]:{aconf.port:d}{DHEat.CLEAR} with {DHEat.WHITEB}{concurrent_sockets:d}{DHEat.CLEAR} concurrent sockets{rate_str}.  No Diffie-Hellman requests will be sent.\n")
             print()
 
             # Make room for the multi-line output.
@@ -369,14 +375,17 @@ class DHEat:
                     server_dh_kex.append(server_kex)
 
             if len(server_dh_kex) == 0:
-                out.d("Skipping DHEat.dh_rate_test() since server does not support any DH algorithms: [%s]" % ", ".join(kex.kex_algorithms))
+                kex_list = ", ".join(kex.kex_algorithms)
+                out.d(f"Skipping DHEat.dh_rate_test() since server does not support any DH algorithms: [{kex_list}]")
                 return ""
             else:
-                out.d("DHEat.dh_rate_test(): starting test; parameters: %f seconds, %u max connections, %u concurrent sockets." % (max_time, max_connections, concurrent_sockets), write_now=True)
+                out.d(f"DHEat.dh_rate_test(): starting test; parameters: {max_time:,.1f} seconds, {max_connections:,d} max connections, {concurrent_sockets:,d} concurrent sockets.", write_now=True)
 
         num_attempted_connections = 0
         num_opened_connections = 0
-        num_exceeded_maxstartups = 0
+        num_em = 0     # Number of "Exceeded MaxStartups" messages.
+        num_naatt = 0  # Number of "Not available at this time" messages.
+        num_invalid_banners = 0
         socket_dict: Dict[socket.socket, float] = {}
         start_timer = time.time()
         now = start_timer
@@ -395,13 +404,15 @@ class DHEat:
                 if (now - last_update) >= 1.0:
                     seconds_running = now - start_timer
                     if multiline_output:
-                        print("\033[5ARun time: %s%.1f%s seconds" % (DHEat.WHITEB, seconds_running, DHEat.CLEAR))
-                        print("TCP SYNs: %s%u%s (total); %s%.1f%s (per second)" % (DHEat.WHITEB, num_attempted_connections, DHEat.CLEAR, DHEat.BLUEB, num_attempted_connections / seconds_running, DHEat.CLEAR))
-                        print("Completed connections: %s%u%s (total); %s%.1f%s (per second)" % (DHEat.WHITEB, num_opened_connections, DHEat.CLEAR, DHEat.BLUEB, num_opened_connections / seconds_running, DHEat.CLEAR))
-                        print("\"Exceeded MaxStartups\" responses: %s%u%s (total); %s%.1f%s (per second)" % (DHEat.WHITEB, num_exceeded_maxstartups, DHEat.CLEAR, DHEat.BLUEB, num_exceeded_maxstartups / seconds_running, DHEat.CLEAR))
-                        print("%s%s%s" % (DHEat.WHITEB, spinner[spinner_index], DHEat.CLEAR))
+                        print(f"\033[7A                            Run time: {DHEat.WHITEB}{seconds_running:,.1f}{DHEat.CLEAR} seconds")
+                        print(f"                            TCP SYNs: {DHEat.WHITEB}{num_attempted_connections / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_attempted_connections:,d}{DHEat.CLEAR} total ")
+                        print(f"               Completed connections: {DHEat.WHITEB}{num_opened_connections / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_opened_connections:,d}{DHEat.CLEAR} total ")
+                        print(f"    \"Exceeded MaxStartups\" responses: {DHEat.WHITEB}{num_em / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_em:,d}{DHEat.CLEAR} total ")
+                        print(f"\"Not allowed at this time\" responses: {DHEat.WHITEB}{num_naatt / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_naatt:,d}{DHEat.CLEAR} total ")
+                        print(f"                     Invalid banners: {DHEat.WHITEB}{num_invalid_banners / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_invalid_banners:,d}{DHEat.CLEAR} total ")
+                        print(DHEat.WHITEB + spinner[spinner_index] + DHEat.CLEAR)
                     else:
-                        print("%s%s%s Run time: %s%.1f%s; TCP SYNs: %s%u%s; Compl. conns: %s%u%s; TCP SYNs/sec: %s%.1f%s; Compl. conns/sec: %s%.1f%s    \r" % (DHEat.WHITEB, spinner[spinner_index], DHEat.CLEAR, DHEat.WHITEB, seconds_running, DHEat.CLEAR, DHEat.WHITEB, num_attempted_connections, DHEat.CLEAR, DHEat.WHITEB, num_opened_connections, DHEat.CLEAR, DHEat.BLUEB, num_attempted_connections / seconds_running, DHEat.CLEAR, DHEat.BLUEB, num_opened_connections / seconds_running, DHEat.CLEAR), end="")
+                        print(f"{DHEat.WHITEB}{spinner[spinner_index]}{DHEat.CLEAR} Run time: {DHEat.WHITEB}{seconds_running:,.1f}{DHEat.CLEAR}; TCP SYNs: {DHEat.WHITEB}{num_attempted_connections:,d}{DHEat.CLEAR}; Compl. conns: {DHEat.WHITEB}{num_opened_connections:,d}{DHEat.CLEAR}; TCP SYNs/sec: {DHEat.BLUEB}{num_attempted_connections / seconds_running:,.1f}{DHEat.CLEAR}; Compl. conns/sec: {DHEat.BLUEB}{num_opened_connections / seconds_running:,.1f}{DHEat.CLEAR}    \r", end="")
                     last_update = now
                     spinner_index = (spinner_index + 1) % 4
 
@@ -435,7 +446,11 @@ class DHEat:
                 s.setblocking(False)
 
                 # out.d("Creating socket (%u of %u already exist)..." % (len(socket_dict), concurrent_sockets), write_now=True)
-                ret = s.connect_ex((target_ip_address, aconf.port))
+                if has_af_unix and (target_address_family == socket.AF_UNIX):
+                    ret = s.connect_ex(target_ip_address)
+                else:
+                    ret = s.connect_ex((target_ip_address, aconf.port))
+
                 num_attempted_connections += 1
                 if ret in [0, errno.EINPROGRESS, errno.EWOULDBLOCK]:
                     socket_dict[s] = now
@@ -463,8 +478,14 @@ class DHEat:
                     num_opened_connections += 1
                     # out.d("Number of opened connections: %u (max: %u)." % (num_opened_connections, max_connections))
                 elif buf == b"Exceeded":
-                    num_exceeded_maxstartups += 1
+                    num_em += 1
                     # out.d("Number of \"Exceeded MaxStartups\": %u" % num_exceeded_maxstartups)
+                elif buf == b"Not allo":
+                    num_naatt += 1
+                    # out.d("Number of \"Not allowed at this time\": {num_naatt:,d}")
+                else:
+                    num_invalid_banners += 1
+                    # out.d("Number of invalid banners: {num_invalid_banners:,d}")
 
                 _close_socket(socket_dict, s)
 
@@ -716,35 +737,39 @@ class DHEat:
         # Print extensive statistics on what just happened.
         seconds_running = time.time() - self.start_timer
         print("\n\n")
-        print("                        %s %sSTATISTICS%s %s" % (self.BAR_CHART, self.WHITEB, self.CLEAR, self.CHART_UPWARDS))
-        print("                           %s----------%s" % (self.WHITEB, self.CLEAR))
+        print(f"                            {self.BAR_CHART} {self.WHITEB}STATISTICS{self.CLEAR} {self.CHART_UPWARDS}")
+        print(f"                               {self.WHITEB}----------{self.CLEAR}")
         print()
-        print("                       Run time: %s%.1f seconds%s" % (self.WHITEB, seconds_running, self.CLEAR))
+        print(f"                           Run time: {self.WHITEB}{seconds_running:,.1f} seconds{self.CLEAR}")
         print()
-        print("      Attempted TCP connections: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_attempted_tcp_connections / seconds_running, self.num_attempted_tcp_connections, self.CLEAR))
-        print("     Successful TCP connections: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_successful_tcp_connections / seconds_running, self.num_successful_tcp_connections, self.CLEAR))
+        print(f"          Attempted TCP connections: {self.WHITEB}{self.num_attempted_tcp_connections / seconds_running:,.1f}/sec, {self.num_attempted_tcp_connections:,d} total{self.CLEAR}")
+        print(f"         Successful TCP connections: {self.WHITEB}{self.num_successful_tcp_connections / seconds_running:,.1f}/sec, {self.num_successful_tcp_connections:,d} total{self.CLEAR}")
         print()
-        print("                  Bytes written: %s%s/sec, %s total%s" % (self.WHITEB, DHEat.add_byte_units(self.num_bytes_written / seconds_running), DHEat.add_byte_units(self.num_bytes_written), self.CLEAR))
+        print(f"                      Bytes written: {self.WHITEB}{DHEat.add_byte_units(self.num_bytes_written / seconds_running)}/sec, {DHEat.add_byte_units(self.num_bytes_written)} total{self.CLEAR}")
         print()
-        print("      Successful DH KEX replies: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_successful_dh_kex / seconds_running, self.num_successful_dh_kex, self.CLEAR))
-        print("      Unexpected DH KEX replies: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_failed_dh_kex / seconds_running, self.num_failed_dh_kex, self.CLEAR))
-        print("\"Exceeded MaxStartups\" replies*: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_openssh_throttled_connections / seconds_running, self.num_openssh_throttled_connections, self.CLEAR))
+        print(f"          Successful DH KEX replies: {self.WHITEB}{self.num_successful_dh_kex / seconds_running:,.1f}/sec, {self.num_successful_dh_kex:,d} total{self.CLEAR}")
+        print(f"          Unexpected DH KEX replies: {self.WHITEB}{self.num_failed_dh_kex / seconds_running:,.1f}/sec, {self.num_failed_dh_kex:,d} total{self.CLEAR}")
+        print(f"    \"Exceeded MaxStartups\" replies*: {self.WHITEB}{self.num_em / seconds_running:,.1f}/sec, {self.num_em:,d} total{self.CLEAR}")
+        print(f"\"Not allowed at this time\" replies+: {self.WHITEB}{self.num_naatt / seconds_running:,.1f}/sec, {self.num_naatt:,d} total{self.CLEAR}")
+        print(f"                    Invalid banners: {self.WHITEB}{self.num_invalid_banners / seconds_running:,.1f}/sec, {self.num_invalid_banners:,.1f} total{self.CLEAR}")
         print()
-        print("            Connection timeouts: %s%.1f/sec, %u total%s (timeout setting: %.1f sec)" % (self.WHITEB, self.num_connect_timeouts / seconds_running, self.num_connect_timeouts, self.CLEAR, self.connect_timeout))
-        print("                  Read timeouts: %s%.1f/sec, %u total%s (timeout setting: %.1f sec)" % (self.WHITEB, self.num_read_timeouts / seconds_running, self.num_read_timeouts, self.CLEAR, self.read_timeout))
-        print("              Socket exceptions: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_socket_exceptions / seconds_running, self.num_socket_exceptions, self.CLEAR))
+        print(f"                Connection timeouts: {self.WHITEB}{self.num_connect_timeouts / seconds_running:,.1f}/sec, {self.num_connect_timeouts:,d} total{self.CLEAR} (timeout setting: {self.connect_timeout:,.1f} sec)")
+        print(f"                      Read timeouts: {self.WHITEB}{self.num_read_timeouts / seconds_running:,.1f}/sec, {self.num_read_timeouts:,d} total{self.CLEAR} (timeout setting: {self.read_timeout:,.1f} sec)")
+        print(f"                  Socket exceptions: {self.WHITEB}{self.num_socket_exceptions / seconds_running:,.1f}/sec, {self.num_socket_exceptions:,d} total{self.CLEAR}")
         print()
 
         if seconds_running < 5.0:
-            print("%sTotal run time was under 5 seconds; try running it for longer to get more accurate analysis.%s" % (DHEat.YELLOWB, DHEat.CLEAR))
+            print(f"{DHEat.YELLOWB}Total run time was under 5 seconds; try running it for longer to get more accurate analysis.{DHEat.CLEAR}")
         elif self.num_successful_tcp_connections / seconds_running < DHEat.MAX_SAFE_RATE:
-            print("Because the number of successful TCP connections per second (%.1f) is less than %.1f, it appears that the target %sis using rate limiting%s to prevent CPU exaustion." % (self.num_successful_tcp_connections / seconds_running, DHEat.MAX_SAFE_RATE, DHEat.GREENB, DHEat.CLEAR))
+            print(f"Because the number of successful TCP connections per second ({self.num_successful_tcp_connections / seconds_running:,.1f}) is less than {DHEat.MAX_SAFE_RATE:,.1f}, it appears that the target {DHEat.GREENB}is using rate limiting{DHEat.CLEAR} to prevent CPU exaustion.")
         else:
-            print("Because the number of successful TCP connections per second (%.1f) is greater than %.1f, it appears that the target %sis NOT using rate limiting%s to prevent CPU exaustion." % (self.num_successful_tcp_connections / seconds_running, DHEat.MAX_SAFE_RATE, DHEat.REDB, DHEat.CLEAR))
+            print(f"Because the number of successful TCP connections per second ({self.num_successful_tcp_connections / seconds_running:,.1f}) is greater than {DHEat.MAX_SAFE_RATE:,.1f}, it appears that the target {DHEat.REDB}is NOT using rate limiting{DHEat.CLEAR} to prevent CPU exaustion.")
 
         print()
         print()
-        print(" * OpenSSH has a throttling mechanism (controlled by the MaxStartups directive) to prevent too many pre-authentication connections from overwhelming the server.  When triggered, the server will probabilistically return \"Exceeded MaxStartups\" instead of the usual SSH banner, then terminate the connection.  In order to maximize the DoS effectiveness, this metric should be greater than zero, though the ideal rate of rejections depends on the target server's CPU resources.")
+        print(" [*] Prior to OpenSSH 9.8, the sole connection throttling mechanism is controlled by the MaxStartups directive. This prevents too many pre-authentication connections from overwhelming the server.  When triggered, the server will probabilistically return \"Exceeded MaxStartups\" instead of the usual SSH banner, then terminate the connection.  In order to maximize the DoS effectiveness, this metric should be greater than zero, though the ideal rate of rejections depends on the target server's CPU resources.")
+        print()
+        print(" [+] Starting in OpenSSH 9.8, a more fine-gained connection throttling mechanism was added via the PerSourcePenalties directive. When triggered, the server returns \"Not allowed at this time\" instead of the usual SSH banner. This countermeasure is more effective than simply relying on the MaxStartups directive, and seems to block this attack under its default settings.")
         print()
 
 
@@ -752,6 +777,10 @@ class DHEat:
     def _resolve_hostname(host: str, ip_version_preference: List[int]) -> Tuple[int, str]:
         '''Resolves a hostname to its IPv4 or IPv6 address, depending on user preference.'''
 
+        # First check if this is a UNIX socket.
+        if host.startswith("unix://"):
+            return int(socket.AF_UNIX), host[7:]
+
         family = socket.AF_UNSPEC
         if len(ip_version_preference) == 1:
             family = socket.AF_INET if ip_version_preference[0] == 4 else socket.AF_INET6
@@ -767,7 +796,6 @@ class DHEat:
     def _run(self) -> bool:
         '''Where all the magic happens.'''
 
-
         self.output()
         if sys.platform == "win32":
             self.output("%sWARNING:%s this feature has not been thoroughly tested on Windows.  It may perform worse than on UNIX OSes." % (self.YELLOWB, self.CLEAR))
@@ -879,14 +907,16 @@ class DHEat:
                     self.num_connect_timeouts += thread_statistics['num_connect_timeouts']
                     self.num_read_timeouts += thread_statistics['num_read_timeouts']
                     self.num_socket_exceptions += thread_statistics['num_socket_exceptions']
-                    self.num_openssh_throttled_connections += thread_statistics['num_openssh_throttled_connections']
+                    self.num_em += thread_statistics['num_em']
+                    self.num_naatt += thread_statistics['num_naatt']
+                    self.num_invalid_banners += thread_statistics['num_invalid_banners']
             except queue.Empty:  # If Queue.get() timeout exceeded.
                 pass
 
             now = time.time()
             if (now - last_update) >= 1.0:
                 seconds_running = now - self.start_timer
-                print("%s%s%s TCP SYNs/sec: %s%u%s; Compl. conns/sec: %s%u%s; Bytes sent/sec: %s%s%s; DH kex/sec: %s%u%s    \r" % (self.WHITEB, spinner[spinner_index], self.CLEAR, self.BLUEB, self.num_attempted_tcp_connections / seconds_running, self.CLEAR, self.BLUEB, self.num_successful_tcp_connections / seconds_running, self.CLEAR, self.BLUEB, DHEat.add_byte_units(self.num_bytes_written / seconds_running), self.CLEAR, self.PURPLEB, self.num_successful_dh_kex / seconds_running, self.CLEAR), end="")
+                print(f"{self.WHITEB}{spinner[spinner_index]}{self.CLEAR} TCP SYNs/sec: {self.BLUEB}{int(self.num_attempted_tcp_connections / seconds_running):,d}{self.CLEAR}; Compl. conns/sec: {self.BLUEB}{self.num_successful_tcp_connections / seconds_running:,.1f}{self.CLEAR}; Bytes sent/sec: {self.BLUEB}{DHEat.add_byte_units(self.num_bytes_written / seconds_running)}{self.CLEAR}; DH kex/sec: {self.PURPLEB}{self.num_successful_dh_kex / seconds_running:,.1f}{self.CLEAR}    \r", end="")
                 last_update = now
                 spinner_index = (spinner_index + 1) % 4
 
@@ -934,13 +964,16 @@ class DHEat:
         num_connect_timeouts = 0
         num_read_timeouts = 0
         num_socket_exceptions = 0
-        num_openssh_throttled_connections = 0
+        num_em = 0     # Number of "Exceeded MaxStartups" messages received.
+        num_naatt = 0  # Number of "Not allowed at this time" messages received.
+        num_invalid_banners = 0
 
         num_loops_since_last_statistics_sync = 0
         while True:
             num_loops_since_last_statistics_sync += 1
 
             # Instead of flooding the parent process with statistics, report our stats only every 5 connections.
+            # TODO: this sends too quickly in the case of application-level rate limiting, resulting in client-side CPU exhaustion instead! :O  Perhaps a dynamic number of loops should be skipped, based on what would result in 1 message per 2-3 seconds.
             if num_loops_since_last_statistics_sync > 5:
                 num_loops_since_last_statistics_sync = 0
 
@@ -953,7 +986,9 @@ class DHEat:
                     'num_connect_timeouts': num_connect_timeouts,
                     'num_read_timeouts': num_read_timeouts,
                     'num_socket_exceptions': num_socket_exceptions,
-                    'num_openssh_throttled_connections': num_openssh_throttled_connections,
+                    'num_em': num_em,
+                    'num_naatt': num_naatt,
+                    'num_invalid_banners': num_invalid_banners
                 })
 
                 # Since we sent our statistics, reset them all back to zero.
@@ -965,7 +1000,9 @@ class DHEat:
                 num_connect_timeouts = 0
                 num_read_timeouts = 0
                 num_socket_exceptions = 0
-                num_openssh_throttled_connections = 0
+                num_em = 0
+                num_naatt = 0
+                num_invalid_banners = 0
 
             s = socket.socket(target_address_family, socket.SOCK_STREAM)
             s.settimeout(connect_timeout)
@@ -1008,11 +1045,16 @@ class DHEat:
             if banner.startswith(b"SSH-2.0-") or banner.startswith(b"SSH-1"):
                 num_successful_tcp_connections += 1
             elif banner == b'Exceeded MaxStartups':
-                num_openssh_throttled_connections += 1
+                num_em += 1
+                _close_socket(s)
+                continue
+            elif banner == b'Not allowed at this time':
+                num_naatt += 1
                 _close_socket(s)
                 continue
             else:
-                self.debug("Invalid banner received: %r" % banner)
+                num_invalid_banners += 1
+                # self.debug("Invalid banner received: %r" % banner)
                 _close_socket(s)
                 continue
 

src/ssh_audit/globals.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2017-2024 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017-2026 Joe Testa (jtesta@positronsecurity.com)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
@@ -22,10 +22,10 @@
    THE SOFTWARE.
 """
 # The version to display.
-VERSION = 'v3.4.0-dev'
+VERSION = 'v3.9.1-dev'
 
 # SSH software to impersonate
-SSH_HEADER = 'SSH-{0}-OpenSSH_8.2'
+SSH_HEADER = 'SSH-{0}-OpenSSH_10.3'
 
 # The URL to the Github issues tracker.
 GITHUB_ISSUES_URL = 'https://github.com/jtesta/ssh-audit/issues'

src/ssh_audit/hardening_guides.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2025 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2025-2026 Joe Testa (jtesta@positronsecurity.com)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
@@ -347,6 +347,52 @@ class Hardening_Guides:
             },
         ],
 
+        "Rocky Linux 10": [
+            {
+                "server_guide": True,
+                "version": 1,
+                "version_date": "2026-06-17",
+                "change_log": "Initial revision. In comparison to the Rocky Linux 9 hardening guide, the following changes were made: the key exchange list was set to include post-quantum algorithms only.",
+                "notes": "all commands below are to be executed as the root user.",
+                "commands": [
+                    {
+                        "heading": "Disable RedHat Crypto Policies",
+                        "comment": "",
+                        "command": "rm -f /etc/ssh/sshd_config.d/40-redhat-crypto-policies.conf"
+                    },
+                    {
+                        "heading": "Re-generate the RSA and ED25519 keys",
+                        "comment": "",
+                        "command": "rm -f /etc/ssh/ssh_host_*\nssh-keygen -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key -N \"\"\nssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key -N \"\""
+                    },
+                    {
+                        "heading": "Restrict supported key exchange, cipher, and MAC algorithms",
+                        "comment": "",
+                        "command": "echo -e \"# Restrict key exchange, cipher, and MAC algorithms, as per sshaudit.com\\n# hardening guide.\\nHostKey /etc/ssh/ssh_host_ed25519_key\\nHostKey /etc/ssh/ssh_host_rsa_key\\n\\nKexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com\\n\\nCiphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-gcm@openssh.com,aes128-ctr\\n\\nMACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-128-etm@openssh.com\\n\\nHostKeyAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\nRequiredRSASize 3072\\n\\nCASignatureAlgorithms sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\nGSSAPIKexAlgorithms gss-curve25519-sha256-,gss-group16-sha512-\\n\\nHostbasedAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-256\\n\\nPubkeyAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\n\" > /etc/ssh/sshd_config.d/rocky10_ssh-audit_hardening.conf"
+                    },
+                    {
+                        "heading": "Restart OpenSSH server",
+                        "comment": "",
+                        "command": "systemctl restart sshd"
+                    },
+                ]
+            },
+            {
+                "server_guide": False,
+                "version": 1,
+                "version_date": "2026-06-17",
+                "change_log": "Initial revision. In comparison to the Rocky Linux 9 hardening guide, the following changes were made: the key exchange list was set to include post-quantum algorithms only.",
+                "notes": "",
+                "commands": [
+                    {
+                        "heading": "Run the following in a terminal to harden the SSH client for the local user:",
+                        "comment": "",
+                        "command": "mkdir -p -m 0700 ~/.ssh; echo -e \"\\nHost *\\n Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-gcm@openssh.com,aes128-ctr\\n\\n KexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com\\n\\n MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-128-etm@openssh.com\\n\\n RequiredRSASize 3072\\n\\n HostKeyAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\n CASignatureAlgorithms sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\n GSSAPIKexAlgorithms gss-curve25519-sha256-,gss-group16-sha512-\\n\\n HostbasedAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-256\\n\\n PubkeyAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-256\\n\\n\" >> ~/.ssh/config"
+                    },
+                ]
+            },
+        ],
+
         "Ubuntu 22.04": [
             {
                 "server_guide": True,
@@ -517,6 +563,47 @@ class Hardening_Guides:
             },
         ],
 
+        "Ubuntu 26.04": [
+            {
+                "server_guide": True,
+                "version": 1,
+                "version_date": "2026-06-14",
+                "change_log": "Initial revision.",
+                "notes": "all commands below are to be executed as the root user.",
+                "commands": [
+                    {
+                        "heading": "Re-generate the ED25519 and RSA keys",
+                        "comment": "",
+                        "command": "rm /etc/ssh/ssh_host_*\nssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key -N \"\"\nssh-keygen -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key -N \"\""
+                    },
+                    {
+                        "heading": "Restrict supported key exchange, cipher, and MAC algorithms",
+                        "comment": "",
+                        "command": "echo -e \"# Restrict key exchange, cipher, and MAC algorithms, as per sshaudit.com\\n# hardening guide.\\nKexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com\\n\\nCiphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-gcm@openssh.com,aes128-ctr\\n\\nMACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com\\n\\nRequiredRSASize 3072\\n\\nHostKeyAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\nCASignatureAlgorithms sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\nGSSAPIKexAlgorithms gss-curve25519-sha256-,gss-group16-sha512-\\n\\nHostbasedAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\nPubkeyAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\" > /etc/ssh/sshd_config.d/ssh-audit_hardening.conf"
+                    },
+                    {
+                        "heading": "Restart OpenSSH server",
+                        "comment": "",
+                        "command": "service ssh restart"
+                    },
+                ]
+            },
+            {
+                "server_guide": False,
+                "version": 1,
+                "version_date": "2026-06-14",
+                "change_log": "Initial revision.",
+                "notes": "",
+                "commands": [
+                    {
+                        "heading": "Run the following in a terminal to harden the SSH client for the local user:",
+                        "comment": "",
+                        "command": "mkdir -p -m 0700 ~/.ssh; echo -e \"\\nHost *\\n Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-gcm@openssh.com,aes128-ctr\\n\\n KexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com\\n\\n MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com\\n\\n RequiredRSASize 3072\\n\\n HostKeyAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\n CASignatureAlgorithms sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256\\n\\n GSSAPIKexAlgorithms gss-curve25519-sha256-,gss-group16-sha512-\\n\\n HostbasedAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-256\\n\\n PubkeyAcceptedAlgorithms sk-ssh-ed25519-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256-cert-v01@openssh.com,rsa-sha2-256\\n\\n\" >> ~/.ssh/config"
+                    },
+                ]
+            },
+        ],
+
         "Linux Mint 21": [
             {
                 "server_guide": False,

src/ssh_audit/software.py

@@ -72,10 +72,29 @@ class Software:
             oversion, opatch = mx.group(1), mx.group(2).strip()
         else:
             oversion, opatch = other, ''
-        if self.version < oversion:
-            return -1
-        elif self.version > oversion:
-            return 1
+
+        # Attempt to parse the versions into floats.
+        float_parse_error = False
+        selfversion_float = 0.0
+        oversion_float = 0.0
+        try:
+            selfversion_float = float(self.version)
+            oversion_float = float(oversion)
+        except ValueError:
+            float_parse_error = True
+
+        # If the versions could not be parsed into floats, use the old string compare method. This returns incorrect results when comparing modern OpenSSH versions ("9.6" > "10.4" evaluates to True!), but removing this may trigger other bugs, and we have no other good options here, soooo...
+        if float_parse_error:
+            if self.version < oversion:
+                return -1
+            elif self.version > oversion:
+                return 1
+        else:  # Float parsing worked, so we'll use this instead. That way (9.6 > 10.4) properly evaluates to False.
+            if selfversion_float < oversion_float:  # pylint: disable=else-if-used
+                return -1
+            elif selfversion_float > oversion_float:
+                return 1
+
         spatch = self.patch or ''
         if self.product == Product.DropbearSSH:
             if not re.match(r'^test\d.*$', opatch):

src/ssh_audit/ssh2_kexdb.py

@@ -81,6 +81,11 @@ class SSH2_KexDB:  # pylint: disable=too-few-public-methods
     INFO_EXTENSION_NEGOTIATION = 'pseudo-algorithm that denotes the peer supports RFC8308 extensions'
     INFO_STRICT_KEX = 'pseudo-algorithm that denotes the peer supports a stricter key exchange method as a counter-measure to the Terrapin attack (CVE-2023-48795)'
 
+    # NIST PQC security levels: https://blog.cloudflare.com/pq-2025/
+    INFO_NIST_PQC_LEVEL_2 = 'rated at NIST PQC level 2 (at least as hard to break as SHA256)'
+    INFO_NIST_PQC_LEVEL_3 = 'rated at NIST PQC level 3 (at least as hard to break as AES-192)'
+    INFO_NIST_PQC_LEVEL_5 = 'rated at NIST PQC level 5 (at least as hard to break as AES-256)'
+
     # Maintains a dictionary per calling thread that yields its own copy of MASTER_DB.  This prevents results from one thread polluting the results of another thread.
     DB_PER_THREAD: Dict[int, Dict[str, Dict[str, List[List[Optional[str]]]]]] = {}
 
@@ -230,6 +235,9 @@ class SSH2_KexDB:  # pylint: disable=too-few-public-methods
             'ecdsa-sha2-nistt571': [[], [FAIL_UNPROVEN], [WARN_RNDSIG_KEY]],
             'eddsa-e382-shake256@libassh.org': [[], [FAIL_UNPROVEN]],
             'eddsa-e521-shake256@libassh.org': [[], [FAIL_UNPROVEN]],
+            'mldsa-44': [[], [], [], [INFO_NIST_PQC_LEVEL_2]],
+            'mldsa-65': [[], [], [], [INFO_NIST_PQC_LEVEL_3]],
+            'mldsa-87': [[], [], [], [INFO_NIST_PQC_LEVEL_5]],
             'null': [[], [FAIL_PLAINTEXT]],
             'pgp-sign-dss': [[], [FAIL_1024BIT_MODULUS]],
             'pgp-sign-rsa': [[], [FAIL_1024BIT_MODULUS]],
@@ -259,6 +267,13 @@ class SSH2_KexDB:  # pylint: disable=too-few-public-methods
             'ssh-gost2001': [[], [FAIL_UNTRUSTED]],
             'ssh-gost2012-256': [[], [FAIL_UNTRUSTED]],
             'ssh-gost2012-512': [[], [FAIL_UNTRUSTED]],
+            'ssh-mldsa-44': [[], [], [], [INFO_NIST_PQC_LEVEL_2]],
+            'ssh-mldsa-65': [[], [], [], [INFO_NIST_PQC_LEVEL_3]],
+            'ssh-mldsa-87': [[], [], [], [INFO_NIST_PQC_LEVEL_5]],
+            'ssh-mldsa44': [[], [], [], [INFO_NIST_PQC_LEVEL_2]],
+            'ssh-mldsa44-ed25519@openssh.com': [['10.4'], [], [], [INFO_NIST_PQC_LEVEL_2]],
+            'ssh-mldsa65': [[], [], [], [INFO_NIST_PQC_LEVEL_3]],
+            'ssh-mldsa87': [[], [], [], [INFO_NIST_PQC_LEVEL_5]],
             'ssh-rsa1': [[], [FAIL_SHA1]],
             'ssh-rsa': [['2.5.0,d0.28,l10.2'], [FAIL_SHA1], [], [INFO_DEPRECATED_IN_OPENSSH88]],
             'ssh-rsa-cert-v00@openssh.com': [['5.4', '6.9'], [FAIL_SHA1], [], [INFO_REMOVED_IN_OPENSSH70]],

src/ssh_audit/ssh_audit.py

@@ -2,7 +2,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2017-2025 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017-2026 Joe Testa (jtesta@positronsecurity.com)
    Copyright (C) 2017 Andris Raugulis (moo@arthepsy.eu)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -794,6 +794,7 @@ def process_commandline(out: OutputBuffer, args: List[str]) -> 'AuditConf':  # p
     parser.add_argument("--list-hardening-guides", action="store_true", dest="list_hardening_guides", default=False, help="list all official, built-in hardening guides for common systems.  Their full names can then be passed to --get-hardening-guide.  Add -v to this option to view hardening guide change logs and prior versions.")
     parser.add_argument("--lookup", action="store", dest="lookup", metavar="alg1[,alg2,...]", type=str, default=None, help="looks up an algorithm(s) without connecting to a server.")
     parser.add_argument("--skip-rate-test", action="store_true", dest="skip_rate_test", default=False, help="skip the connection rate test during standard audits (used to safely infer whether the DHEat attack is viable)")
+    parser.add_argument("--socks5", action="store", dest="socks5_proxy", metavar="host:port", type=str, default=None, help="connect via a SOCKS5 proxy (implies --skip-rate-test)")
     parser.add_argument("--threads", action="store", dest="threads", metavar="N", type=int, default=32, help="number of threads to use when scanning multiple targets (-T/--targets) (default: %(default)s)")
 
 
@@ -817,11 +818,17 @@ def process_commandline(out: OutputBuffer, args: List[str]) -> 'AuditConf':  # p
         aconf.list_policies = argument.list_policies
         aconf.manual = argument.manual
         aconf.skip_rate_test = argument.skip_rate_test
+        aconf.socks5_proxy = argument.socks5_proxy
         oport = argument.oport
 
         if argument.batch is True:
             aconf.batch = True
 
+        # Skip the rate test if we're using a SOCKS5 proxy.
+        if aconf.socks5_proxy is not None:
+            out.d("Disabling rate test since SOCKS5 proxy is set.", write_now=True)
+            aconf.skip_rate_test = True
+
         # If one -j was given, turn on JSON output.  If -jj was given, enable indentation.
         aconf.json = argument.json > 0
         if argument.json > 1:
@@ -888,8 +895,8 @@ def process_commandline(out: OutputBuffer, args: List[str]) -> 'AuditConf':  # p
             aconf.verbose = True
             out.verbose = True
 
-    except argparse.ArgumentError as err:
-        out.fail(str(err), write_now=True)
+    except (argparse.ArgumentError, ValueError) as err:
+        out.fail(f"Error: {str(err)}", write_now=True)
         parser.print_help()
         sys.exit(exitcodes.UNKNOWN_ERROR)
 
@@ -915,19 +922,21 @@ def process_commandline(out: OutputBuffer, args: List[str]) -> 'AuditConf':  # p
         Hardening_Guides.print_hardening_guide(out, argument.get_hardening_guide)
         sys.exit(exitcodes.GOOD)
 
+    # If we're doing a server audit against a single target.
     if aconf.client_audit is False and aconf.target_file is None:
-        if oport is not None:
-            host = argument.host
-        else:
+        host = argument.host
+        if oport is None:
             host, port = Utils.parse_host_and_port(argument.host)
 
         if not host and aconf.target_file is None:
             out.fail("target host is not specified", write_now=True)
             sys.exit(exitcodes.UNKNOWN_ERROR)
 
-    if oport is None and aconf.client_audit:  # The default port to listen on during a client audit is 2222.
+    # For client audits, if an explicit port isn't set, default to 2222/tcp.
+    if aconf.client_audit and oport is None:
         port = 2222
 
+    # If an explicit port was set by the user, parse it.
     if oport is not None:
         port = Utils.parse_int(oport)
         if port < 1 or port > 65535:
@@ -1144,7 +1153,7 @@ def audit(out: OutputBuffer, aconf: AuditConf, print_target: bool = False) -> in
     out.debug = aconf.debug
     out.level = aconf.level
     out.use_colors = aconf.colors
-    s = SSH_Socket(out, aconf.host, aconf.port, aconf.ip_version_preference, aconf.timeout, aconf.timeout_set)
+    s = SSH_Socket(out, aconf.host, aconf.port, aconf.ip_version_preference, aconf.timeout, aconf.timeout_set, aconf.socks5_proxy)
 
     if aconf.client_audit:
         out.v("Listening for client connection on port %d..." % aconf.port, write_now=True)

src/ssh_audit/ssh_socket.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2017-2025 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017-2026 Joe Testa (jtesta@positronsecurity.com)
    Copyright (C) 2017 Andris Raugulis (moo@arthepsy.eu)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -51,7 +51,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
 
     SM_BANNER_SENT = 1
 
-    def __init__(self, outputbuffer: 'OutputBuffer', host: Optional[str], port: int, ip_version_preference: List[int] = [], timeout: Union[int, float] = 5, timeout_set: bool = False) -> None:  # pylint: disable=dangerous-default-value
+    def __init__(self, outputbuffer: 'OutputBuffer', host: Optional[str], port: int, ip_version_preference: List[int] = [], timeout: Union[int, float] = 5, timeout_set: bool = False, socks5_proxy: Optional[str] = None) -> None:  # pylint: disable=dangerous-default-value
         super(SSH_Socket, self).__init__()
         self.__outputbuffer = outputbuffer
         self.__sock: Optional[socket.socket] = None
@@ -72,6 +72,8 @@ class SSH_Socket(ReadBuf, WriteBuf):
         self.__timeout_set = timeout_set
         self.client_host: Optional[str] = None
         self.client_port = None
+        self.__socks5_proxy = socks5_proxy  # SOCKS5 proxy in "host:port" format, or None
+
 
     def _resolve(self) -> Iterable[Tuple[int, Tuple[Any, ...]]]:
         """Resolves a hostname into a list of IPs
@@ -95,11 +97,13 @@ class SSH_Socket(ReadBuf, WriteBuf):
             if socktype == socket.SOCK_STREAM:
                 yield af, addr
 
-    # Listens on a server socket and accepts one connection (used for
-    # auditing client connections).
+
     def listen_and_accept(self) -> None:
+        '''Listens on a server socket and accepts one connection (used for auditing client connections).'''
 
         try:
+            self.__outputbuffer.d(f"Listening on 0.0.0.0:{self.__port}...", write_now=True)
+
             # Socket to listen on all IPv4 addresses.
             s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
             s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
@@ -110,6 +114,8 @@ class SSH_Socket(ReadBuf, WriteBuf):
             print("Warning: failed to listen on any IPv4 interfaces: %s" % str(e), file=sys.stderr)
 
         try:
+            self.__outputbuffer.d(f"Listening on [::]:{self.__port}...", write_now=True)
+
             # Socket to listen on all IPv6 addresses.
             s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
             s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
@@ -150,11 +156,27 @@ class SSH_Socket(ReadBuf, WriteBuf):
         c.settimeout(self.__timeout)
         self.__sock = c
 
+
     def connect(self) -> Optional[str]:
         '''Returns None on success, or an error string.'''
         err = None
         s = None
+
         try:
+            # If we're connecting to a UNIX socket.
+            if self.__host.startswith("unix://"):
+                s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+                s.settimeout(self.__timeout)
+                s.connect(self.__host[7:])
+                self.__sock = s
+                return None
+
+            # If we're connecting through a SOCKS5 proxy.
+            if self.__socks5_proxy is not None:
+                self.__sock = self._connect_via_socks5()
+                return None
+
+            # We're connecting to an Internet host.
             for af, addr in self._resolve():
                 s = socket.socket(af, socket.SOCK_STREAM)
                 s.settimeout(self.__timeout)
@@ -162,16 +184,112 @@ class SSH_Socket(ReadBuf, WriteBuf):
                 s.connect(addr)
                 self.__sock = s
                 return None
+
         except socket.error as e:
             err = e
             self._close_socket(s)
+
         if err is None:
             errm = 'host {} has no DNS records'.format(self.__host)
         else:
             errt = (self.__host, self.__port, err)
             errm = 'cannot connect to {} port {}: {}'.format(*errt)
+
         return '[exception] {}'.format(errm)
 
+
+    def _connect_via_socks5(self) -> socket.socket:
+        '''Connect to the target host:port via a SOCKS5 proxy. Returns a socket on success, or raises an exception.'''
+
+        def __socks5_recv_exact(s: socket.socket, n: int) -> Optional[bytes]:
+            '''Read exactly n bytes from socket s, returning None on EOF.'''
+            buf = b''
+            while len(buf) < n:
+                chunk = s.recv(n - len(buf))
+                if not chunk:
+                    return None
+                buf += chunk
+            return buf
+
+        # Parse the "host:port" string into its parts.
+        proxy_host, proxy_port = Utils.parse_host_and_port(self.__socks5_proxy) if self.__socks5_proxy is not None else ("", 0)
+
+        self.__outputbuffer.d("Connecting to SOCKS5 proxy %s:%d..." % (proxy_host, proxy_port), write_now=True)
+        s = socket.create_connection((proxy_host, proxy_port), timeout=self.__timeout)
+
+        # SOCKS5 greeting: version=5, nmethods=1, method=0 (no auth)
+        s.sendall(b'\x05\x01\x00')
+        resp = __socks5_recv_exact(s, 2)
+        if resp is None:
+            raise socket.error("no response from SOCKS5 proxy during handshake")
+        if resp[0] != 5:
+            raise socket.error("SOCKS5 proxy returned unexpected version: {}".format(resp[0]))
+        if resp[1] == 0xff:
+            raise socket.error("SOCKS5 proxy rejected all authentication methods")
+        if resp[1] != 0:
+            raise socket.error("SOCKS5 proxy requires authentication (method {:d}), but only no-auth is supported".format(resp[1]))
+
+        # Set the type and host encoding appropriately, depending on if we're sending a hostname, IPv4, or IPv6 address. The ATYP field is 3 when the client is sending a hostname.
+        atyp = 3
+        _enc_host = self.__host.encode('idna')
+        dst_addr = struct.pack('!B', len(_enc_host)) + _enc_host
+        if Utils.is_ipv4_address(self.__host):
+            atyp = 1
+            dst_addr = socket.inet_pton(socket.AF_INET, self.__host)
+        elif Utils.is_ipv6_address(self.__host):
+            atyp = 4
+            dst_addr = socket.inet_pton(socket.AF_INET6, self.__host)
+
+        # SOCKS5 connect request: version=5, cmd=1 (connect), rsv=0, atyp
+        request = struct.pack('!BBBB', 5, 1, 0, atyp) + dst_addr + struct.pack('!H', self.__port)
+        self.__outputbuffer.d("Requesting SOCKS5 proxy to connect to %s:%d..." % (self.__host, self.__port), write_now=True)
+        s.sendall(request)
+
+        # Read the fixed part of the response (4 bytes: ver, rep, rsv, atyp)
+        hdr = __socks5_recv_exact(s, 4)
+        if hdr is None:
+            raise socket.error("no response from SOCKS5 proxy during connect")
+
+        server_version = hdr[0]
+        reply = hdr[1]
+        # rsv = hdr[2]  # Reserved, set to 0 as per RFC1928.
+        atyp = hdr[3]
+
+        if server_version != 5:
+            raise socket.error("SOCKS5 proxy returned unexpected version in connect response: {}".format(hdr[0]))
+
+        if reply != 0:
+            socks5_errors = {
+                1: "general SOCKS server failure",
+                2: "connection not allowed by ruleset",
+                3: "network unreachable",
+                4: "host unreachable",
+                5: "connection refused",
+                6: "TTL expired",
+                7: "command not supported",
+                8: "address type not supported",
+            }
+
+            err = socks5_errors[reply] if reply in socks5_errors else f"unknown error: {reply}"
+            raise socket.error("SOCKS5 proxy connect failed: {}".format(err))
+
+        # Read and discard the bound address from the response
+        if atyp == 1:    # IPv4
+            __socks5_recv_exact(s, 4 + 2)
+        elif atyp == 4:  # IPv6
+            __socks5_recv_exact(s, 16 + 2)
+        elif atyp == 3:  # domain name
+            alen_data = __socks5_recv_exact(s, 1)
+            if alen_data is None:
+                raise socket.error("truncated SOCKS5 response")
+            __socks5_recv_exact(s, alen_data[0] + 2)
+        else:
+            raise socket.error("SOCKS5 proxy returned unknown address type: {}".format(atyp))
+
+        self.__outputbuffer.d("Successfully established SOCKS5 connection.", write_now=True)
+        return s
+
+
     def get_banner(self) -> Tuple[Optional['Banner'], List[str], Optional[str]]:
         self.__outputbuffer.d('Getting banner...', write_now=True)
 
@@ -201,6 +319,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
 
         return self.__banner, self.__header, e
 
+
     def recv(self, size: int = 2048) -> Tuple[int, Optional[str]]:
         if self.__sock is None:
             return -1, 'not connected'
@@ -221,6 +340,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
         self._buf.seek(pos, 0)
         return len(data), None
 
+
     def send(self, data: bytes) -> Tuple[int, Optional[str]]:
         if self.__sock is None:
             return -1, 'not connected'
@@ -243,16 +363,19 @@ class SSH_Socket(ReadBuf, WriteBuf):
         kex.write(self)
         self.send_packet()
 
+
     def send_banner(self, banner: str) -> None:
         self.send(banner.encode() + b'\r\n')
         self.__state = max(self.__state, self.SM_BANNER_SENT)
 
+
     def ensure_read(self, size: int) -> None:
         while self.unread_len < size:
             s, e = self.recv()
             if s < 0:
                 raise SSH_Socket.InsufficientReadException(e)
 
+
     def read_packet(self) -> Tuple[int, bytes]:
         try:
             header = WriteBuf()
@@ -284,6 +407,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
                 e = ex.args[0].encode('utf-8')
             return -1, e
 
+
     def send_packet(self) -> Tuple[int, Optional[str]]:
         payload = self.write_flush()
         padding = -(len(payload) + 5) % 8
@@ -294,10 +418,12 @@ class SSH_Socket(ReadBuf, WriteBuf):
         data = struct.pack('>Ib', plen, padding) + payload + pad_bytes
         return self.send(data)
 
+
     def is_connected(self) -> bool:
         """Returns true if this Socket is connected, False otherwise."""
         return self.__sock is not None
 
+
     def close(self) -> None:
         self.__cleanup()
         self.reset()
@@ -305,6 +431,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
         self.__header = []
         self.__banner = None
 
+
     def _close_socket(self, s: Optional[socket.socket]) -> None:
         try:
             if s is not None:
@@ -313,9 +440,11 @@ class SSH_Socket(ReadBuf, WriteBuf):
         except Exception:
             pass
 
+
     def __del__(self) -> None:
         self.__cleanup()
 
+
     def __cleanup(self) -> None:
         self._close_socket(self.__sock)
         for sock in self.__sock_map.values():

src/ssh_audit/utils.py

@@ -1,7 +1,7 @@
 """
    The MIT License (MIT)
 
-   Copyright (C) 2017-2020 Joe Testa (jtesta@positronsecurity.com)
+   Copyright (C) 2017-2026 Joe Testa (jtesta@positronsecurity.com)
    Copyright (C) 2017 Andris Raugulis (moo@arthepsy.eu)
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -134,6 +134,10 @@ class Utils:
         host = host_and_port
         port = default_port
 
+        # If we have a UNIX socket path, do no further processing.
+        if host.startswith("unix://"):
+            return host, 1
+
         mx = re.match(r'^\[([^\]]+)\](?::(\d+))?$', host_and_port)
         if mx is not None:
             host = mx.group(1)
@@ -149,6 +153,17 @@ class Utils:
 
         return host, port
 
+    @staticmethod
+    def is_ipv4_address(address: str) -> bool:
+        '''Returns True if address is an IPv4 address, otherwise False.'''
+        is_ipv4 = True
+        try:
+            ipaddress.IPv4Address(address)
+        except ipaddress.AddressValueError:
+            is_ipv4 = False
+
+        return is_ipv4
+
     @staticmethod
     def is_ipv6_address(address: str) -> bool:
         '''Returns True if address is an IPv6 address, otherwise False.'''

ssh-audit.1

@@ -1,4 +1,4 @@
-.TH SSH-AUDIT 1 "August 17, 2025"
+.TH SSH-AUDIT 1 "June 20, 2026"
 .SH NAME
 \fBssh-audit\fP \- SSH server & client configuration auditor
 .SH SYNOPSIS
@@ -141,6 +141,11 @@ Runs a policy audit against a target using the specified policy (see \fBPOLICY A
 .br
 Skips the connection rate test during standard audits.  By default, a few dozen TCP connections are created with the target host to see if connection throttling is implemented (this can safely infer whether the target is vulnerable to the DHEat attack; see CVE-2002-20001).
 
+.TP
+.B     \-\-socks5 host:port
+.br
+Connects through a SOCKS5 proxy. Rate tests are automatically skipped (i.e.: implies \-\-skip\-rate\-test).
+
 .TP
 .B -t, \-\-timeout=<secs>
 .br
@@ -149,7 +154,7 @@ The timeout, in seconds, for creating connections and reading data from the sock
 .TP
 .B -T, \-\-targets=<hosts.txt>
 .br
-A file containing a list of target hosts.  Each line must have one host, in the format of HOST[:PORT].  Use -p/--port to set the default port for all hosts.  Use --threads to control concurrent scans.
+A file containing a list of target hosts.  Each line must have one host, in the format of HOST[:PORT] (or for UNIX sockets, use "unix://path/to/socket").  Use -p/--port to set the default port for all hosts.  Use --threads to control concurrent scans.
 
 .TP
 .B     \-\-threads=<threads>
@@ -188,6 +193,7 @@ ssh-audit 127.0.0.1
 ssh-audit 127.0.0.1:222
 ssh-audit ::1
 ssh-audit [::1]:222
+ssh-audit unix:///run/ssh-unix-local/socket
 .fi
 .RE
 

test/test_auditconf.py

@@ -165,3 +165,19 @@ class TestAuditConf:
         self._test_conf(conf, host='localhost', level='fail')
         with pytest.raises(SystemExit):
             conf = c('-l something localhost')
+
+    def test_audit_conf_process_commandline_socks5_proxy(self):
+        c = lambda x: self.process_commandline(self.OutputBuffer, x.split())  # noqa
+
+        assert c('--socks5 127.0.0.1:1080 localhost').socks5_proxy == '127.0.0.1:1080'
+        assert c('--socks5 [fe80::aaaa:bbbb:cccc:dddd]:1080 localhost').socks5_proxy == '[fe80::aaaa:bbbb:cccc:dddd]:1080'
+        assert c('--socks5 somehost.lol:1080 localhost').socks5_proxy == 'somehost.lol:1080'
+
+        with pytest.raises(SystemExit):
+            c('--socks5 localhost localhost')
+
+        with pytest.raises(SystemExit):
+            c('--socks5 localhost:0 localhost')
+
+        with pytest.raises(SystemExit):
+            c('--socks5 localhost:65536 localhost')