329. ECCE, xterm and X forwarding: fixing broken "tail -f on output" in ECCE/'untrusted X11 forwarding' error

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The problem
In ECCE when you highlight a running job on a remote server which you've set up with the frontendMachine option (here and here and here) which is a ROCKS 5.4.3/CentOS server and e.g. hit Alt+L or "Run Mgmt"/"Tail -f on Output file" and nothing happens, and when you set ECCE to provide verbose output (add "ECCE_RCOM_LOGMODE true" to ecce/apps/siteconfig/site_runtime) you see the following errors:

X11 connection rejected because of wrong authentication.
X connection to localhost:43.0 broken (explicit kill or server shutdown).

and

OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
Warning: untrusted X11 forwarding setup failed: xauth key data not generated
Warning: No xauth data; using fake authentication data for X11 forwarding.

Obviously there are non-ECCE related situation where you may see these errors too. Doesn't matter -- same solution.

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The diagnostics

cat /etc/ssh/sshd_config |grep X11

X11Forwarding yes
X11DisplayOffset 10
cat /etc/ssh/ssh_config |grep X11|grep -v ^#

ForwardX11 yes

sudo cat /etc/ssh/sshd_config |grep X11|grep -v ^#

X11Forwarding yes
X11DisplayOffset 10

So, why localhost:43? And why isn't it working? From my workstation to the cluster which is connected to the net via the front node, and then from the cluster front to the cluster front's local name.

ssh -X server.external.dns
echo $DISPLAY

localhost:42.0

ssh -X server.local.dns

Warning: untrusted X11 forwarding setup failed: xauth key data not generated
Warning: No xauth data; using fake authentication data for X11 forwarding.
echo $DISPLAY

localhost:44.0

yet

ssh -Y server.local.dns

works fine.

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The solution:
Simpler than I thought:
I edited ~/.ssh/config on the server, and did

Host server.local.dns
Hostname server.local.dns
User me
ForwardX11 yes 
ForwardX11Trusted yes

And now it works!

Presumably I could've just edited /etc/ssh_config instead, but it's a multi-user cluster and I'm happier to change things on a user-by-user basis.