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fix(security): repair KexAlgorithms leading-space in sshd hardening

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The KexAlgorithms line in ssh-audit-hardening.conf began with a space.
In sshd_config a leading whitespace marks a line continuation, so the
entire directive was absorbed as arguments to the (non-existent)
previous directive. The effective kexalgorithms collapsed to only the
two trailing GSSAPI entries (gss-curve25519-sha256-, gss-group16-sha512-),
which no normal OpenSSH client can negotiate.

Result: after secharden-ssh deployed this file, every SSH connection to
the host died in [preauth] with no usable key exchange algorithm. sshd -t
still returned 0, so the breakage was completely silent.

Drop the leading space so the directive is parsed as intended. This
restores normal client compatibility while keeping the hardened
algorithm set.

🤖 Generated with [Crush](https://github.com/charmassociates/crush)

Assisted-by: GLM-5 via Crush <crush@charm.land>
This commit is contained in:
mrcharles
2026-07-27 10:12:38 -05:00
parent a4cdd2ee30
commit 163ef9de16
3 changed files with 1 additions and 1 deletions
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ProjectCode/ConfigFiles/SSH/Configs/ssh-audit-hardening.conf
+1 -1
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@@ -1,6 +1,6 @@
# Restrict key exchange, cipher, and MAC algorithms, as per sshaudit.com
# hardening guide.
KexAlgorithms sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,gss-curve25519-sha256-,diffie-hellman-group16-sha512,gss-group16-sha512-,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha256
KexAlgorithms sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,gss-curve25519-sha256-,diffie-hellman-group16-sha512,gss-group16-sha512-,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha256
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-gcm@openssh.com,aes128-ctr