keep-persistent-ssh-session-using-autossh-and-cron

local.fwd.ssh.config

Host 1.2.3.4 autossh
    Hostname 1.2.3.4
    User autossh
    SendEnv LANG LC_*
    IdentityFile ~/.ssh/autossh
    ConnectTimeout 0
    HashKnownHosts yes
    LocalForward 2222 localhost:22
    ServerAliveInterval 30
    ServerAliveCountMax 3

remote.fwd.ssh.config

Host 1.2.3.4 autossh
    Hostname 1.2.3.4
    User autossh
    SendEnv LANG LC_*
    IdentityFile ~/.ssh/autossh
    ConnectTimeout 0
    HashKnownHosts yes
    RemoteForward 2222 localhost:22
    ServerAliveInterval 30
    ServerAliveCountMax 3

sshd_config

Match User autossh
   #AllowTcpForwarding yes
   #X11Forwarding no
   #PermitTunnel no
   #GatewayPorts no
   AllowAgentForwarding no
   PermitOpen localhost:2222
   ForceCommand echo 'This account can only be used for [reason]'