FreeNX 0.7.3 under CentOS 6.3 - Negotiating link parameters

Question

since some days I try to get freenx (CentOS package 0.7.3) running under CentOS 6.3. It is like found on many websites: First login is successfull, after that all login attempts fail with the negotiation error.

A simple ssh with the same username to the server is successful. For the installation I followed the howTo on http://wiki.centos.org/HowTos/FreeNX

Strange is that the changelog of FreeNX 0.7.3 tells that this bug was fixed. Has anybody been successful in running FreeNX under CentOS without this problem and knows how to fix it?

Frank

EDIT: Here is the log from /var/log/nx/

It is not the nx user, seems to be the display:

-- NX SERVER START:  - ORIG_COMMAND=
Info: Using fds #4 and #3 for communication with nxnode.
HELLO NXSERVER - Version 3.2.0-74-SVN OS (GPL, using backend: not detected)
NX> 105 hello NXCLIENT - Version 3.2.0
NX> 134 Accepted protocol: 3.2.0
NX> 105 SET SHELL_MODE SHELL
NX> 105 SET AUTH_MODE PASSWORD
NX> 105 login
NX> 101 User: frank
NX> 102 Password:
NX> 103 Welcome to: vServerIT user: frank
NX> 105 listsession --user="frank" --status="suspended,running" --geometry="1680x1050x32+render" --type="unix-gnome"
NX> 127 Sessions list of user 'frank' for reconnect:

Display Type             Session ID                       Options  Depth    Screen         Status      Session Name
------- ---------------- -------------------------------- -------- -----     --------------    ----------- ------------------------------
1000    unix-gnome       61521246CE49DE6B212C56E60D61963A -RD--PSA    24 1674x982          Suspended   Virtualmachine
NX> 148 Server capacity: not reached for user: frank
NX> 105 restoresession  --link="lan" --backingstore="1" --cache="16M" --images="64M"     --shmem="1" --shpix="1" --strict="0" --composite="1" --media="0" --session="Virtualmachine" --type="unix-gnome" --geometry="1674x982" --client="winnt"     --keyboard="pc102/de" --id="61521246CE49DE6B212C56E60D61963A" --resize="1"

NX> 1000 NXNODE - Version 3.2.0-74-SVN OS (GPL, using backend: not detected)
NX> 1009 Session status: resuming
NX> 700 Session id: vServerIT-1000-61521246CE49DE6B212C56E60D61963A
NX> 705 Session display: 1000
NX> 703 Session type: unix-gnome
NX> 701 Proxy cookie: cb22faf565e74bbb6b10f77cf0b55eff
NX> 702 Proxy IP: 127.0.0.1
NX> 706 Agent cookie: cb22faf565e74bbb6b10f77cf0b55eff
NX> 704 Session cache: unix-gnome
NX> 707 SSL tunneling: 0
NX> 710 Session status: running
NX> 710 Session status: running
NX> 1002 Commit
NX> 1006 Session status: running
NX> 1002 Commit
NX> 1006 Session status: running
NX> 1002 Commit
NX> 1006 Session status: running
NX> 105 bye
Bye
NX> 999 Bye
NX> 1001 Bye.
NX> 105 NX> 596 Error: Session  failed. Reason was: Session: Display failure detected at 'Sat Sep  8 11:57:25 2012'.
NX> 1009 Session status: suspending
NX> 1005 Session status: suspended
NX> 596 Error: Session restore failed. Reason was: Session: Display failure detected at 'Sat Sep  8 11:57:25 2012'.
NX> 1001 Bye.

Answer 1

It's difficult to know for sure if you don't have the full error log from FreeNX, but my guess is that the negotiation error is caused by the "nx" user account, not your user account. Maybe the the home directory for the "nx" user has changed, the RSA keys changed, the user priviledge is set incorrectly, etc. I've seen the errors many times before.

FreeNX has stopped woking for me after v0.8 or so, and I switched to NoMachine NX free edition instead. But even then I still saw enough negotiation failures, key-mapping issues with OSX, etc., that I simply gave up on NX/FreeNX and use TightVNC instead, the negotiation stage is a lot faster and much more reliable. NX usually take 5-10 sec to connect, while TightVNC + SSH connects almost instantly.

But in any case, if you want to stay with NX but can't track down exactly why negotiation is failing, try installing the NoMachine version of NX instead and see if that solves your problem. It did for me.