[CentOS] iptables settings for X11 forwarding in CentOS 6.2

[zGreenfelder]

On Fri, Mar 29, 2013 at 12:37 PM, Pat Haley <phaley at mit.edu> wrote:
>
> Hi,
>
> Actually we're talking about both SSH and XDMCP X11 forwarding.
> Both seem to be currently disabled by the iptables.
>
> We'll try out what you suggest and get back with the results.
> Thanks.
>
> Pat

iptables should have no effect (well.   I guess if you do some really
odd config settings it -could-, but that's a bit of an edge case) on
ssh X tunnels.   check your /etc/ssh/sshd_config for
X11Forwarding
it should be set to yes.   if you have iptables that apply to
localhost/127.0.0.0/8 network, then I suppose iptables could be part
of the problem.   but I'd think it'd make sense to drop most all of
those rules.

it might also be helpful to look at the output of from your external
machine when you run ssh -vvvv -X user at clusterhost (I wouldn't send it
all to the list, cuz it'll be a ton of nonsense, but the last page or
of output lines have helped me find issues in the past)

... or am I completely off in left field and you're saying you're
unable to ssh into your machines?
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