16.5.1. Port Forwarding

Each F-Secure configuration you create may have different ports forwarded. To set up forwarding to a particular remote host, disconnect from that host (if you're connected), open the Properties window, and notice the Tunneling category. Select Local Tunneling to set up local forwarding (see Figure 16-2), or Remote Tunneling for remote forwarding, respectively. [Section 9.2.3, "Comparing Local and Remote PortForwarding"] Either way, you are prompted for similar information:

Source Port:

The local port number

Destination Host:

The remote hostname

Destination Port:

The remote port number

Application to Start:

An external application to be launched when this port is forwarded

Figure 16-2. F-Secure SSH Client local port forwarding options

For example, to tunnel a telnet connection (TCP port 23) through SSH to connect to server.example.com, you can specify:

Source port: 8500 (any random port number)

Destination Host: server.example.com

Destination Port: 23

Application to Start: c:\windows\telnet.exe

Once you've made your choices, reopen the SSH connection, and the ports will be forwarded for the duration of your connection.

Note that F-Secure SSH Client forbids remote connections to locally forwarded ports. This security feature is analogous to specifying "GatewayPorts no". [Section 9.2.1.1, "Local forwarding and GatewayPorts"]

16.5.2. X Forwarding

The X Window System is the most popular windowing software for Unix machines. If you want to run remote X clients that open windows on your PC, you need:

• A remote host, running an SSH server, that has X client programs available

• An X server running on your PC under Windows, such as Hummingbird's eXceed

SSH makes your X connection secure by a process called X forwarding. [Section 9.3, "X Forwarding"] Turning on X forwarding is trivial in F-Secure SSH Client: open the Properties window, select Tunneling, and put a checkmark in the box Enable X11 Tunneling. You may also select the X display number, which you also may change during your SSH session.

To secure an X connection by forwarding it through SSH, first run F-Secure SSH Client and establish a secure terminal connection to the SSH server machine. Then run your PC's X server, disabling its login features such as XDM. Now simply invoke X clients on the server machine, and their windows will open on your local X display.