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Refined GEX testing against OpenSSH servers: when the fallback mechanism is suspected of being triggered, perform an additional test to obtain more accurate results.

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Joe Testa
2023-09-03 16:13:00 -04:00
parent 3f2fdbaa3d
commit 199e75f6cd
19 changed files with 100 additions and 104 deletions
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5
test/docker/expected_results/openssh_8.0p1_test1.txt
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@ -21,9 +21,8 @@
`- [info] available since OpenSSH 5.7, Dropbear SSH 2013.62
(kex) ecdh-sha2-nistp521 -- [fail] using elliptic curves that are suspected as being backdoored by the U.S. National Security Agency
`- [info] available since OpenSSH 5.7, Dropbear SSH 2013.62
(kex) diffie-hellman-group-exchange-sha256 (2048-bit) -- [warn] 2048-bit modulus only provides 112-bits of symmetric strength
`- [info] available since OpenSSH 4.4
`- [info] A bug in OpenSSH causes it to fall back to a 2048-bit modulus regardless of server configuration (https://bugzilla.mindrot.org/show_bug.cgi?id=2793)
(kex) diffie-hellman-group-exchange-sha256 (4096-bit) -- [info] available since OpenSSH 4.4
`- [info] OpenSSH's GEX fallback mechanism was triggered during testing. Very old SSH clients will still be able to create connections using a 2048-bit modulus, though modern clients will use 4096. This can only be disabled by recompiling the code (see https://github.com/openssh/openssh-portable/blob/V_9_4/dh.c#L477).
(kex) diffie-hellman-group16-sha512 -- [info] available since OpenSSH 7.3, Dropbear SSH 2016.73
(kex) diffie-hellman-group18-sha512 -- [info] available since OpenSSH 7.3
(kex) diffie-hellman-group14-sha256 -- [warn] 2048-bit modulus only provides 112-bits of symmetric strength