SSH Tunnel Examples

tunnels.sh

# simple local port forwarding example for vault
# - exposes localhost:8200 to 10.20.30.40:8200 via bastion.internal.company
# - bastion.internal.company has to be able to reach 10.20.30.40:8200
ssh -M -S http_vault -fnNT -L 8200:10.20.30.40:8200 [email protected]

alias tunnel_http='ssh -L <host_a>:<port_a>:<host_c>:<port_c> -i ~/.ssh/id_rsa <host_b>'

where host_a:port_a is the host you're actually trying to hit from your local box
  and host_b        is the host you're able to ssh into from host_a
  and host_c:port_c is the application you're trying to reach (and accessible via this ip/port from host_b)
  
# A better way to manage them:
alias tunnel_make_http_8888='ssh -M -S http_8888 -fnNT -L <host_a>:<port_a>:<host_c>:<port_c -i ~/.ssh/id_rsa <host_b>'
alias tunnel_check_http_8888='ssh -S http_8888 -O check <host_b>'
alias tunnel_stop_http_8888='ssh -S http_8888 -O exit <host_b>'

# An even better way to manage them:
function tunnelto(){
  if [[ -z $5 ]]; then
    echo 'Usage: ssh -M -S $5 -fnNT -L ${HOSTNAME}:$1:$3:$4 -i /home/username/.ssh/id_rsa $2';
    return 1;
  fi;
 
  host0=$(host $(hostname) | awk '{print $4}')
  host1=$2
  host2=$3
  port0=$1
  port2=$4
  name=$5
  sshkey=${6:-/home/${USER}/.ssh/id_rsa}
  sshuser=${7:-${USER}}
  ssh -M -S $name -fnNT -L $host0:$port0:$host2:$port2 -i $sshkey $sshuser@$host1
}
 
function tunnelsrunning(){
  ps x | grep 'ssh -M' | grep -v grep | awk '{print $8}'
}
 
function tunnelkill(){
  ssh -S ${1} -O exit $(ps x | grep ssh | grep ${1} | awk '{print $NF}')
}
 
function tunnelkillall(){
  for i in $(tunnelsrunning); do
    tunnelkill ${i}
  done
}