I am having trouble getting x window forwarding over ssh to work. Mandrake 9.1 is running on both the server computer and the client laptop I'm using to connect to the server. (It worked out of the box with Mandrake 8.1). I can successfully ssh to the server, and I can start an x application -- that is, when I type xclock, a process id shows up. But the x application does not appear on my local machine (the laptop) and I get the following error message:

Can't open display:[laptop ip address]:10.0

My /etc/ssh/sshd_config file on the server computer contains the following X-related lines:

Protocol 2,1
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes <-- commenting this out seems to make no difference

My /etc/ssh/ssh_config file on the client laptop has the following:

Host *
ForwardAgent yes
ForwardX11 yes
Protocol 2,1

When I echo $DISPLAY on the server, I get
localhost:10.0
But it also doesn't work if I manually set DISPLAY to [laptop ip address]:10.0.

Using xhost + [laptop] doesn't help.

The iptables firewalls on both machines accept all connections from the local network, and the IP addresses in each machines' /etc/hosts files correctly match up.

I have checked the MAN page for SSH to no avail, as well as searched the internet extensively.

Any help would be appreciated.

Thanks.

Ah, fixed it myself. Turns out I needed to add a rule as the first rule in the OUTPUT chain of iptables on the remote server to allow localhost to connect to localhost as follows:

iptables -I OUTPUT 1 -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT


Also, I needed to let ssh automatically set the DISPLAY environment to localhost:10.0, instead of manually setting it to laptop:10.0, which is probably why I needed the localhost iptables rule above.

I hope others may benefit from my mistakes.