mrcharles
163ef9de16
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>
19 lines
1.4 KiB
Plaintext
19 lines
1.4 KiB
Plaintext
# Restrict key exchange, cipher, and MAC algorithms, as per sshaudit.com
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# hardening guide.
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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
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Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-gcm@openssh.com,aes128-ctr
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MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-128-etm@openssh.com
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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
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RequiredRSASize 3072
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CASignatureAlgorithms sk-ssh-ed25519@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256
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GSSAPIKexAlgorithms gss-curve25519-sha256-,gss-group16-sha512-
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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
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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 |