Files
bpfire/config/ssh/ssh_config
Peter Müller 68545eb2d1 OpenSSH: Order symmetric ciphers by strength
We also wish to prefer AES over Chacha/Poly, given the
prevalence of hardware accelaration for the former.

Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
2024-09-22 14:40:07 +00:00

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# OpenSSH client configuration file for IPFire
#
# The full documentation is available at: https://man.openbsd.org/ssh_config
#
# Set some basic hardening options for all connections
Host *
# Disable undocumented roaming feature as it is known to be vulnerable
UseRoaming no
# Only use secure crypto algorithms
KexAlgorithms sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com,mlkem768x25519-sha256,curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
Ciphers aes256-gcm@openssh.com,aes256-ctr,chacha20-poly1305@openssh.com,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,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com
# Always visualise server host keys (helps to identify key based MITM attacks)
VisualHostKey yes
# Use SSHFP (might work on some up-to-date networks) to look up host keys
VerifyHostKeyDNS yes
# Send SSH-based keep alive messages to connected server to avoid broken connections
ServerAliveInterval 10
ServerAliveCountMax 30
# Disable TCP keep alive messages since they can be spoofed and we have SSH-based
# keep alive messages enabled; there is no need to do things twice here
TCPKeepAlive no
# Ensure only allowed authentication methods are used
PreferredAuthentications publickey,keyboard-interactive,password
# Prevent information leak by hashing ~/.ssh/known_hosts
HashKnownHosts yes
# EOF