/etc/ssh/ssh config

OpenSSH client configuration file.

Man page: https://man7.org/linux/man-pages/man5/ssh_config.5.html

• ~/.ssh/config
• /etc/ssh/ssh_config

Basic example

Host your_machine_name
    Hostname IP_or_dns_name
    User USERNAME_TO_CONNECT
    IdentityFile ~/.ssh/id_ed25519       #Private key

Example with auto tmux and session persistence

Host your_machine_name
    Hostname IP_or_dns_name
    User USERNAME_TO_CONNECT
    IdentityFile ~/.ssh/id_ed25519       #Private key
    RemoteCommand sudo su - -c "tmux new -A -s main"
    RequestTTY yes
    ControlMaster auto
    ControlPath ~/.ssh/sockets/%C
    ControlPersist 10h
    ServerAliveInterval 60

Example with ProxyJump

Host machine_name_for_ssh_client
    ProxyJump YOUR_SERVER_TO_USE_AS_JUMPSERVER
    Hostname (IP or hostname)
    Port 22
    User USERNAME_TO_CONNECT
    IdentityFile ~/.ssh/id_ed25519

Configure OpenSSH to reuse ssh connections

RequestTTY yes
ControlMaster auto
ControlPath ~/.ssh/sockets/%r@%h-%p
ControlPersist 36000

OpenSSH Changelog

• 2016 OpenSSH 7.3 include include.d/your_file

To allow connection to some Cisco IOS devices:

• KexAlgorithms +diffie-hellman-group14-sha1

Directives

• HashKnownHosts
• StrictHostKeyChecking
• KexAlgorithms
• RemoteCommand
• RequestTTY
• ServerAliveInterval
• ForwardAgent
• ProxyJump

Errors

• bad configuration option:

Activities

• Configure OpenSSH to reuse ssh connections

Related terms

• Default usernames
• .pg_service.conf
• viconfig
• aws ssm start-session
• IdentityAgent

See also

• /etc/ssh/ssh_config, ~/.ssh/config (man), RemoteCommand, RequestTTY, ServerAliveInterval, UseKeychain, ForwardAgent, ProxyJump, ControlMaster, ControlPath, ControlPersist
• OpenSSH: ssh (man), ssh -O, -i, -t, -T, -N, -L, -V, /etc/ssh/ssh_config, ssh --help
• OpenSSH (changelog): /etc/ssh/sshd_config | /etc/ssh/ssh_config | ~/.ssh/ | openSSL | sshd logs | sftp | scp | authorized_keys | ssh-keygen | ssh-keyscan | ssh-add | ssh-agent | ssh | Ssh -O stop | ssh-copy-id | CheckHostIP | UseKeychain, OpenSSF, ~/.ssh/authorized_keys