shell-things/etc/ssh/ssh_config

# This works as a /etc/ssh/ssh_config or ~/.ssh/config like how I keep
# using it. Higher option takes priority (keep `Host *` bottom)

# User specific configs
Include ~/.ssh/config.d/*.conf
# Debian includes this
Include /etc/ssh/ssh_config.d/*.conf

Host *
    # Path for the control socket.
    ControlPath ~/.ssh/sockets/socket-%r@%h:%p
    # Multiple sessions over single connection
    ControlMaster yes
    # Keep connection open in the background even after connection has been
    # closed.
    ControlPersist yes

    # SSH Agent forwarding is behind a lot of security breaches, never do it
    # Most recently https://github.com/matrix-org/matrix.org/issues/371
    ForwardAgent no
    # Never do that either https://security.stackexchange.com/a/14817/234532
    ForwardX11 no

    # Debian sets this as yes, upstream no. TODO: What is it?
    #GSSAPIAuthentication yes

    # Ensure KnownHosts are unreadable if leaked.
    HashKnownHosts yes

    LogLevel VERBOSE
    Protocol 2

    # Tor through openbsd netcat (Fedora: netcat)
    ProxyCommand netcat -X 5 -x localhost:9050 %h %p

    # Always try public key authentication.
    PubkeyAuthentication yes

    # Send needed environment variables. I don't like setting wildcards
    # and LC_ALL is disabled on purpouse.
    SendEnv EDITOR LANG LANGUAGE LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT LC_IDENTIFICATION TERM TZ

    # If the server doesn't reply in three "pings", connection is dead.
    # Defaults to 3 anyway, but I add it here for clearity and
    # in case it decides to change in the future.
    ServerAliveCountMax 3

    # "ping" the server every minute.
    ServerAliveInterval 60

    # OpenSSH 6.8+ - ask all host keys from servers.
    # I trust the server admins and ways to identify the keys (DNSSEC,
    # manual).
    UpdateHostKeys yes

    # Workaround CVE-2016-0777 & CVE-0778 on OpenSSH < 7.1p2
    UseRoaming no

    # Verify SSHFP records. If this is yes, the question is skipped when
    # DNSSEC is used, but apparently only "ask" and "no" write known_hosts
    # However with "ask" you won't be told whether the zone is signed, so
    # I consider "yes" to be the least evil.
    VerifyHostKeyDNS yes

    # Display key ascii art on connection. Makes noticing changed keys easier,
    # although it's ambiguous and similar pattern may go past unnoticed.
    VisualHostKey yes