config/ssh/ssh_config

   1 # OpenSSH client configuration file for IPFire
   2 #
   3 # The full documentation is available at: https://man.openbsd.org/ssh_config
   4 #
   5
   6 # Set some basic hardening options for all connections
   7 Host *
   8         # Disable undocumented roaming feature as it is known to be vulnerable
   9         UseRoaming no
  10
  11         # Only use secure crypto algorithms
  12         KexAlgorithms sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
  13         Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
  14         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
  15
  16         # Always visualise server host keys (helps to identify key based MITM attacks)
  17         VisualHostKey yes
  18
  19         # Use SSHFP (might work on some up-to-date networks) to look up host keys
  20         VerifyHostKeyDNS yes
  21
  22         # Send SSH-based keep alive messages to connected server to avoid broken connections
  23         ServerAliveInterval 10
  24         ServerAliveCountMax 30
  25
  26         # Disable TCP keep alive messages since they can be spoofed and we have SSH-based
  27         # keep alive messages enabled; there is no need to do things twice here
  28         TCPKeepAlive no
  29
  30         # Ensure only allowed authentication methods are used
  31         PreferredAuthentications publickey,keyboard-interactive,password
  32
  33         # Prevent information leak by hashing ~/.ssh/known_hosts
  34         HashKnownHosts yes
  35
  36 # EOF