Further information: it occurred to me some of the environment might be missing starting in this way. Turns out that indeed, x2goclient needs one of the env variables from the user that are not kept. Which I don't know, but by starting the shell in the new namespace with sudo -E, I can at least run x2goclient successfully...

Best,
Wim

On Thu, Jun 25, 2015 at 10:02 AM Wim De Smet <kromagg@gmail.com> wrote:
Hello,

For various reasons I'm trying out running x2goclient from a separate net namespace (ip netns) by using a macvlan interface with a separate IP onto my main interface.

So I do as root:
ip netns add sepns
ip link add link eth0 mvlan1 type macvlan
ip link set dev mvlan1 netns sepns
ip netns exec sepns bash
dhclient mvlan0
su <normaluser>
x2goclient

This isolates x2goclient from the normal networking of the system. Now this seems to work fine for firefox for instance, but there's something crucial missing in the environment for x2goclient, as:
1) it starts up with a different theme than usual, apparently themes are working in a reduced state
2) it will fail to properly connect and eventually segfault

Here's some output from the log when it's trying to connect:
x2go-INFO-1> "Starting x2goclient..."
x2go-WARNING-1> "Can't load translator: :/x2goclient_en_us"
x2go-WARNING-2> "Can't load translator: :/qt_en_US"
x2go-INFO-3> "Started  x2goclient."
x2go-DEBUG-../onmainwindow.cpp:490> "$HOME=/home/kromagg"
x2go-DEBUG-../onmainwindow.cpp:2117> Reading 1 sessions from config file.
x2go-INFO-8> "Starting connection to server: ..."
x2go-DEBUG-../onmainwindow.cpp:2696> Start new ssh connection to server:"...":"22" krbLogin: false
x2go-DEBUG-../onmainwindow.cpp:2791> SSH connection established.
x2go-DEBUG-../onmainwindow.cpp:3051> Continue normal x2go session
x2go-DEBUG-../onmainwindow.cpp:3395> "10538|wdesmet-51-1434971717_stDGNOME_dp24|51|labo582.localdomain|S|...|30018|30019|2015-06-25T09:30:25|wdesmet|246116|30020|
"
x2go-DEBUG-../onmainwindow.cpp:4718> Agent output: "gr_port=30018
sound_port=30019
fs_port=30020
"
x2go-DEBUG-../onmainwindow.cpp:4896> New gr_port: "30018"
x2go-DEBUG-../onmainwindow.cpp:4903> New sound_port: "30019"
x2go-DEBUG-../onmainwindow.cpp:4910> New fs_port: "30020"
x2go-DEBUG-../onmainwindow.cpp:5328> "Starting NX proxy, command: nxproxy -S nx/nx,options=/home/kromagg/.x2go/S-wdesmet-51-1434971717_stDGNOME_dp24/options:51"
x2go-DEBUG-../onmainwindow.cpp:5644> Proxy wrote on stderr: "
NXPROXY - Version 3.5.0

Copyright (C) 2001, 2011 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Proxy running in client mode with pid '9722'.
Session: Starting session at 'Thu Jun 25 09:37:15 2015'.
Info: Connecting to remote host 'localhost:31018'.
"
x2go-DEBUG-../onmainwindow.cpp:10190> "Searching proxy win: X2GO-wdesmet-51-1434971717_stDGNOME_dp24"
x2go-DEBUG-../onmainwindow.cpp:11733> "Searching window with title: X2GO-wdesmet-51-1434971717_stDGNOME_dp24"
x2go-DEBUG-../onmainwindow.cpp:10190> "Searching proxy win: X2GO-wdesmet-51-1434971717_stDGNOME_dp24"
x2go-DEBUG-../onmainwindow.cpp:11733> "Searching window with title: X2GO-wdesmet-51-1434971717_stDGNOME_dp24"
x2go-DEBUG-../onmainwindow.cpp:10190> "Searching proxy win: X2GO-wdesmet-51-1434971717_stDGNOME_dp24"
x2go-DEBUG-../onmainwindow.cpp:11733> "Searching window with title: X2GO-wdesmet-51-1434971717_stDGNOME_dp24"

It just keeps going like that until finally:
x2go-WARNING-5> "Waiting for proxy to exit."
x2go-WARNING-6> "Failed, killing the proxy."
x2go-DEBUG-../onmainwindow.cpp:5556> Waiting for proxy to exit.
x2go-DEBUG-../onmainwindow.cpp:5581> Deleting SSH connection instance.
x2go-DEBUG-../onmainwindow.cpp:5583> Deleted  SSH connection instance.
Segmentation fault (core dumped)

So I was wondering if any devs had insight on what is going on here. I've tried to flush all cache in the .x2go folder, but this seemed to have no effect. I did at one point have these X11 errors pop up:

X Error: BadWindow (invalid Window parameter) 3
  Major opcode: 20 (X_GetProperty)
  Resource id:  0x5400005
X Error: BadWindow (invalid Window parameter) 3
  Major opcode: 15 (X_QueryTree)
  Resource id:  0x5400005

I'm assuming something needs a  unix socket that is not available, but not sure how this works or why it fails so badly. Any insight would be appreciated.

Regards,
wim