config/ssh/sshd_config

   1 # OpenSSH server configuration file for IPFire
   2 #
   3 # The full documentation is available at: https://man.openbsd.org/sshd_config
   4 #
   5
   6 # Only allow version 2 of SSH protocol
   7 Protocol 2
   8
   9 # Listen on port 22 by default
  10 Port 22
  11
  12 # Listen on every interface and IPv4 only
  13 AddressFamily inet
  14 ListenAddress 0.0.0.0
  15
  16 # Limit authentication timeout to 30 seconds
  17 LoginGraceTime 30s
  18
  19 # Limit maximum instanctes to prevent DoS
  20 MaxStartups 5
  21
  22 # Only allow safe crypto algorithms (may break some _very_ outdated clients)
  23 # See also: https://stribika.github.io/2015/01/04/secure-secure-shell.html
  24 KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
  25 Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
  26 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
  27
  28 # Only allow cryptographically safe SSH host keys (adjust paths if needed)
  29 HostKey /etc/ssh/ssh_host_ed25519_key
  30 HostKey /etc/ssh/ssh_host_ecdsa_key
  31 HostKey /etc/ssh/ssh_host_rsa_key
  32
  33 # Only allow login via public key by default
  34 PubkeyAuthentication yes
  35 PasswordAuthentication no
  36 ChallengeResponseAuthentication no
  37
  38 # Permit root login as there is no other user in IPFire 2.x
  39 PermitRootLogin yes
  40
  41 # Ignore user ~/.ssh/known_hosts file
  42 IgnoreUserKnownHosts yes
  43
  44 # Do not allow any kind of forwarding (provides only low security);
  45 # some of them might need to be re-enabled if SSH server is a jump platform
  46 AllowTcpForwarding no
  47 AllowAgentForwarding no
  48 PermitOpen none
  49
  50 # Detect broken sessions by sending keep-alive messages to clients via SSH connection
  51 ClientAliveInterval 10
  52
  53 # Close unresponsive SSH sessions which fail to answer keep-alive
  54 ClientAliveCountMax 6
  55
  56 # Add support for SFTP
  57 Subsystem       sftp    /usr/lib/openssh/sftp-server
  58
  59 # EOF