ssh -D9999 username@foreignhost.com

ssh -L 9999:host2:1234 -N host1

ssh -L 9999:localhost:9999 host1 ssh -L 9999:localhost:1234 -N host2

ssh -L 9998:host2:22 -N host1
ssh -L 9999:localhost:1234 -N -p 9998 localhost

Host host2
  ProxyCommand ssh host1 -W %h:%p

Host *.mycompany.com
  ProxyCommand ssh gateway.mycompany.com -W %h:%p

Host host2
  ProxyJump host1

#!/bin/bash
ssh -f -L some_port:private_machine:22 user@gateway "sleep 10" && ssh -p some_port private_user@localhost

#!/usr/bin/perl

$iport = 13021;
$first = 1;

foreach (@ARGV) {
  if (/^-/) {
    $args .= " $_";
  }
  elsif (/^((.+)@)?([^:]+):?(d+)?$/) {
    $user = $1;
    $host = $3;
    $port = $4 || 22;
    if ($first) {
      $cmd = "ssh ${user}${host} -p $port -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no";
      $args = '';
      $first = 0;
    }
    else {
      $cmd .= " -L $iport:$host:$port";
      push @cmds, "$cmd -f sleep 10 $args";
      $cmd = "ssh ${user}localhost -p $iport -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no";
      $args = '';
      $iport ++;
    }
  }
}
push @cmds, "$cmd $args";

foreach (@cmds) {
  print "$_n";
  system($_);
}

mssh HOSTA HOSTB HOSTC

mssh user1@HOSTA:1234 user2@HOSTB:1222 user3@HOSTC:78231

mssh HOSTA HOSTB HOSTC -X

mssh HOSTA HOSTB -L8080:HOSTC:8080

Host *+*
    ProxyCommand ssh $(echo %h | sed 's/+[^+]*$//;s/([^+%%]*)%%([^+]*)$/2 -l 1/;s/:/ -p /') nc $(echo %h | sed 's/^.*+//;/:/!s/$/ %p/;s/:/ /')

ssh -D9999 host1+host2 -l username

ssh -L 9999:host2:80 -R 9999:localhost:9999 host1

ssh2 -L 1234:localhost:23 username@host

ssh2 -R 1234:localhost:23 username@host

ssh -J jumpuser1@jumphost1,jumpuser2@jumphost2,...,jumpuserN@jumphostN user@host

our local computer <---> server 1 <---> server 2

LocalPC            <--->  hostname: mit.edu         <---> hec.edu
                          username: bob                   username: john
                          password: dylan123              password: doe456

Host HEC
    HostName hec.edu
    User john
    ProxyCommand ssh bob@mit.edu -W %h:%p

ssh -D9991 HEC