#Setup ssh tunnel to localhost on linux full#
#Setup ssh tunnel to localhost on linux software#

Let us take the specific example of creating a local port essentially going through a two gateways but accessing a remote HTTP service on yet another node. If you focus on making a chain of ssh commands work, you will be able to simplify afterward but I highly recommend you get it to work using this canonical syntax first. You will log to gateway as user and create a port $REMOTEPORT there. % ssh -L $LOCALPORT:localhost:$REMOTEPORT syntax is essentially saying that $LOCALPORT will be created on localhost which is visible to gateway. We will assume each HOP will use the syntax port forwardingįirst, let us stick to one and one command syntax convention only as the syntax is complicated enough to confuse many. Let us ramp this a notch up and create multiple tunnels.

#Setup ssh tunnel to localhost on linux full#

Modulo the fact that nx01 SSH 'protocol' does more than a regular ssh, NX will be able to open a full session on your laptop or desktop.

#Setup ssh tunnel to localhost on linux software#

So, whenever you start a NX client on your local machine and ask it to connect to port 1234, you essentially ask the client software to access via the ssh protocol (all the way through a tunnel going through a gateway node). In this case, is not directly accessible where you are but (a) the gateway is and you can log there as user and (b) can access. Port 22 is by the way, the SSH default port. When connecting to that port, you would essentially, through login to (as user) access port 22 on. % ssh -L 1234::22 would create a local port 1234. Whenever you will need to access the service, you will be able to connect to a local port 3000.Ī more standard example at facilities would be something like Here again -f and -N are used but unlike the previous command, you log to a node able to communicate to via port 5222. Within the same generic syntax, you could create a 2 HOPS tunnel

2 HOPS syntax, a gateway AND a second remote node (accessible from a gateway) In other words, you will be able to send Emails via a local port 1234 even though (a) the real mail-server is a remote one and (b) perhaps can only be accessed via SSH (and all other ports are blocked). Whenever you connect to that local port, what will happen is that you will be tunneled through as user user and connect to on port 25 (SMTP). Would create on your local node a port 1234.

There are optional arguments and ssh command line switches.Īn example of that would be create an SMTP local handler to a remote host using REMOTEPORT=25. Here -f indicates to stop before anything is executed (wait) while -N indicates to not execute any command but create on the local machine (where you issue the ssh command) a local port $LOCALPORT which will essentially allow to access port $REMOTEPORT available on. In our first examples, where to connect is identical to where we want to create a tunnel. The -L does not fully specify what to do - you also need to tell ssh (as usual) where it will connect to create $LOCALPORT::$REMOTEPORT or a gateway server. The middle server name is the remote host or node to which the tunnel will be created. The port number on the left hand-side is the port which is local to the machine where you issue the ssh command and the port on the right hand-side is the port on the remote server. L is the option allowing to create a tunnel. The syntax used to create tunnels is not always immediate so, through examples, we will carefully go through options and syntax.īasic syntax - simple tunnels to a remote service (1 or 2 HOPS) illustrated General syntax: % ssh 1 HOP syntax (only one remote host is involved) Other use may be to run a service as if you were 'inside' a network. For example, tunnels made through gateways may allow you to access an internal Web server while you are on a Wireless or create a local port allowing you to print to a printer only available on a specific network to which you have no specific access to. Creating SSH tunnels can be a powerful tool in your every day work in an environment where many devices are located in different networks.