In the simplest case, you use tunnelopen the way you would use open:
tunnelopen afp://remotehost/The script finds a free local port, sets up a tunnel from that port to the service on the remote host, and then opens a URL to the local port. After the connection for the service is done, the ssh tunnel exits automatically (unless you specify otherwise).
tunnelopen --login user afp://remotehost/
tunnelopen -l user@thirdhost afp://remotehost/Note that you have to specify a hostname in this case, even if it's the same.
In the simplest case, tunnelopen lets you do exactly what you normally do:
tunnelopen afp://pool99.myisp.net/But when you do this, there is really no such machine as pool99.myisp.net. For this to work, you must have configured your home router to forward incoming ssh to a particular machine on your home network. The above command will let you access afp on that machine, even though it is not actually pool99.myisp.net. It's probably something like 192.168.1.100 (and maybe you named it too).
The reason this works is that if you are not using three-party tunneling, then tunnelopen creates an ssh tunnel that forwards to "localhost" on the remote machine. "localhost" should always point a machine at itself, no matter what it's address is.
If you need to access a resource on some other machine behind your NAT, you could configure other ports to forward ssh to other machines. But actually you can still use three party tunnels without this. But in this case you DO have to use the private address for the resource you want:
tunnelopen -l firstname.lastname@example.org afp://192.168.1.101/This works, because the address in the URL is only used on the remote end of the ssh tunnel, where the address is correct. If you have a nameserver set up on your home network (many home routers do this automatically) then you can also use a local hostname, even though it doesn't exist on the outside network:
tunnelopen -l email@example.com vnc://whale/As a general rule, the hostname inside the URL is the private name of the resource, and the hostname in the --login option is the public name for it. The exception is that tunnelopen let's you use the public name in the URL, and skip the private name altogether, in the case where there is no actual three-party tunneling.
tunnelopen --daemon http://internal.webserver.com/path/you/want.htmlWhen this is used, the ssh tunnel never dies. If you want to get rid of it, you'll have to hunt for the process ("ps -x | grep 'ssh -L'), and kill it by hand. It will also let you know what port is being used, so you can figure out how to connect to the tunnel.
URLs will show up pointing to the local tunnel, e.g. "http://localhost:12345/". How well this will work depends in part on how the remote web page is written. You'll only be able to click through liks that do not specify the full hostname. For instance if a link is specified as "../foo.html", then your browser will figure out the server name from your current server, "http://localhost:12345/". If the web page has full URLs to internal resources, you won't be able to click through them.
This feature can also be accomplished with a timeout. Normally, tunnelopen sets up tunnels with a 30 second timeout to give time for the connection to set up (this really means that all tunnels are re-usable for 30 seconds). You can specify an alternate timeout with the "--timeout" or "-t" option. Time is normally in seconds, but can be followed by an m, h, or d to specify minutes, hours, or days. If the timeout is 60 seconds or longer, tunnelopen will report the port being used, just as it does with the -d option.
But you have to know what you are doing! If you set up a shared tunnel on a public network, the entire internet can use this tunnel to get past the firewall that your tunnel is bypassing.
tunnelopen --shared --daemon http://internal.webserver.com/Once you've set up the tunnel, you'll have to tell others how to access the resource, since they won't have it opened automatically. In this example, you'll have to look at the URL that you get, and tell other people on your local network to use that. It might typically be "http://192.168.1.100:12345/", or "http://whale.local:12345/"
This option relies on having hostnames correctly set to values that your network will understand.
That's about it really, except for the "--help" or "-h" option:
host$ tunnelopen -h Usage: tunnelopen [options] URL URL - currently this can only be vnc, afp, http, or https Options are: -s/--shared sets up a connection that all local computers can access (may be VERY insecure if your local network is not private) -d/--daemon keeps the tunnel running after the first connection exits (a good idea if --shared is used). Can't be used with --timeout. -t/--timeout keeps the tunnel running for at least timeout seconds. Defaults to 30, to leave time for connection setup. Can be set to longer values to simulate --daemon, but still automatically exit eventually. May also be specified in minutes, hours or days, by adding an m, h, or d at the end of the number, e.g. "-t 3h" Can't be used with --daemon. -l/--login user[@host] specifies the username for login to the remote system and if a host is also provided, you will ssh into this host, even if that is not where the tunnel is going. This third party connection gets around a Leopard afp bug. If login is not specified it uses your current login name. -p/--port specifies an alternate ssh port, if your ssh server doesn't listen on the default port (22). -h/--help show this message
* It would be possible to get this script to work on other platforms, but it would need additional information on how to start up the appropriate applications for various services. This script benefits from OS X's great "open" command, which let me sidestep all of that.
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