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

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

@@ -51,7 +51,7 @@ usage: ssh-audit.py [-h] [-4] [-6] [-b] [-c] [-d]
                     [--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
@@ -239,9 +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):
 
@@ -252,7 +252,10 @@ 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.

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.
+# Reset local files that may have been changed through a previous run.
-rm -rf parts/ prime/ snap/ stage/ build/ dist/ src/*.egg-info/ ssh-audit*.snap
+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.
+# Set the version field.
-echo -e "\nversion: '${snap_version}'" >> snapcraft.yaml
+sed -i "s/version: \"\"/version: \"${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"

snapcraft.yaml

@@ -1,23 +1,34 @@
 name: ssh-audit
-# 'version' field will be automatically added by build_snap.sh.
+title: ssh-audit
-license: 'MIT'
 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>
-
+contact:
-base: core22
+  - 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:
+platforms:
-  - build-on: [amd64]
+  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/dheat.py

@@ -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
@@ -322,8 +324,12 @@ class DHEat:
             except OSError:
                 pass
 
+            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)
         target_address_family, target_ip_address = DHEat._resolve_hostname(aconf.host, aconf.ip_version_preference)
@@ -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(f"\033[7A                            Run time: {DHEat.WHITEB}{seconds_running:,.1f}{DHEat.CLEAR} seconds")
-                        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(f"                            TCP SYNs: {DHEat.WHITEB}{num_attempted_connections / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_attempted_connections:,d}{DHEat.CLEAR} total ")
-                        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(f"               Completed connections: {DHEat.WHITEB}{num_opened_connections / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_opened_connections:,d}{DHEat.CLEAR} total ")
-                        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(f"    \"Exceeded MaxStartups\" responses: {DHEat.WHITEB}{num_em / seconds_running:,.1f}/sec{DHEat.CLEAR}; {DHEat.WHITEB}{num_em:,d}{DHEat.CLEAR} total ")
-                        print("%s%s%s" % (DHEat.WHITEB, spinner[spinner_index], DHEat.CLEAR))
+                        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 +446,7 @@ class DHEat:
                 s.setblocking(False)
 
                 # out.d("Creating socket (%u of %u already exist)..." % (len(socket_dict), concurrent_sockets), write_now=True)
-                if target_address_family == socket.AF_UNIX:
+                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))
@@ -467,8 +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)
 
@@ -720,35 +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(f"                            {self.BAR_CHART} {self.WHITEB}STATISTICS{self.CLEAR} {self.CHART_UPWARDS}")
-        print("                           %s----------%s" % (self.WHITEB, self.CLEAR))
+        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(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("     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"         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(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("      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(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("\"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"    \"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(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("                  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(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("              Socket exceptions: %s%.1f/sec, %u total%s" % (self.WHITEB, self.num_socket_exceptions / seconds_running, self.num_socket_exceptions, self.CLEAR))
+        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()
 
 
@@ -775,7 +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))
@@ -887,14 +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
 
@@ -942,13 +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
 
@@ -961,7 +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.
@@ -973,7 +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)
@@ -1016,11 +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'