autossh -M 20000 -f -N your_public_server -R 1234:localhost:22 -C

cd ~/.ssh/

echo "ServerAliveInterval 180" >> config

ServerAliveCountMax xxxx (high number)

while true
do
  ssh <ssh_options> [user@]hostname
  sleep 15
done

tun1:2345:respawn:/usr/bin/ssh -i /path/to/rsaKey -f -N -o "ServerAliveInterval 180" -R 55002:localhost:22 user@publicip 'sleep 365d'

start on net-device-up IFACE=eth0
stop on runlevel [01S6]
respawn
respawn limit 180 900
exec ssh -i /path/to/rsaKey -N -o "ServerAliveInterval 180" -R 55002:localhost:22 user@publicip
post-stop script
    sleep 5
end script

~/.ssh/config

ServerAliveInterval 15
ServerAliveCountMax 4

ServerAliveCountMax
         Sets the number of server alive messages (see below) which may be
         sent without ssh(1) receiving any messages back from the server.
         If this threshold is reached while server alive messages are
         being sent, ssh will disconnect from the server, terminating the
         session.  It is important to note that the use of server alive
         messages is very different from TCPKeepAlive (below).  The server
         alive messages are sent through the encrypted channel and there‐
         fore will not be spoofable.  The TCP keepalive option enabled by
         TCPKeepAlive is spoofable.  The server alive mechanism is valu‐
         able when the client or server depend on knowing when a connec‐
         tion has become inactive.

         The default value is 3.  If, for example, ServerAliveInterval
         (see below) is set to 15 and ServerAliveCountMax is left at the
         default, if the server becomes unresponsive, ssh will disconnect
         after approximately 45 seconds.  This option applies to protocol
         version 2 only.

 ServerAliveInterval
         Sets a timeout interval in seconds after which if no data has
         been received from the server, ssh(1) will send a message through
         the encrypted channel to request a response from the server.  The
         default is 0, indicating that these messages will not be sent to
         the server.  This option applies to protocol version 2 only.

[Unit]
Description=SSH Tunnel
After=network.target

[Service]
Restart=always
RestartSec=20
User=sshtunnel
ExecStart=/bin/ssh -NT -o ServerAliveInterval=60 -L 5900:localhost:5900 user@otherserver

[Install]
WantedBy=multi-user.target

screen
ssh -R ......

screen
Ctrl + a + d

#!/bin/bash
read -s -p "Password: " pass
while true
do
    sshpass -p "$pass" ssh user@address -p port
    sleep 1
done