The problem is that this switch to little Endian is available on Power8 only and it is dependent to the Linux distro. Because it is new, most of the Linux distro are BigEndian today. (This could change in the future).

Only Ubuntu move to ppc64le.

So we can't easily switch to LE with fedora are redhat today.

Sébastien Chabrolles Power Systems Benchmark Specialist IBM Client Center, Montpellier 1 rue vieille poste 34000 Montpellier FRANCE Tel +33 4 67 34 40 95 Email : s.chabrolles@fr.ibm.com

Le 11 juin 2014 à 13:51, "Stefan Baur" <newsgroups.mail2@stefanbaur.de> a écrit :

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Am 11.06.2014 13:30, schrieb Mike Gabriel:

...

As this is a very special case, I cannot give more advise on this without being contracted and payed for the time I would have to give for helping with a solution.

Do you think you could at least give him a hint as to where that message is pulling the IP from and how it is being mangled/processed before that?

My guess is that there's some self-made conversion routine somewhere that only works on little-endian architectures like x86 and x64.

PPC64 is big-endian by default.

@Sebastien: Wikipedia claims that PPC64 can be switched to little-endian, though big-endian is the default. Could you please check if such a switch is feasible for you and if it makes the problem go away?

• -Stefan -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

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Package: x2goagent severity: normal version: 3.5.0.24

Note: Crossposting and Reply-To'ing to X2Go-Dev due to the need for a C/C++ coder, also, turning it into a bug so we can keep track of this.

Here's the output the user gets as the connection refuses to establish itself:

quoting Sebastien Chabrolles:

running as X2Go Agent

NXAGENT - Version 3.5.0

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

Info: Agent running with pid '24808'. Session: Starting session at 'Sat Jun 7 15:37:37 2014'. Info: Proxy running in server mode with pid '24808'. Info: Waiting for connection from 'localhost' on port '30003'. Warning: Refusing connection from '225.3.10.80'. .80' on port '30003'. I don't know what is this IP address !!!!!

And at a later attempt, Sebastien received this output:

running as X2Go Agent

NXAGENT - Version 3.5.0

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

Info: Agent running with pid '10710'. Session: Starting session at 'Wed Jun 11 23:02:09 2014'. Info: Proxy running in server mode with pid '10710'. Info: Waiting for connection from 'localhost' on port '30006'. Warning: Refusing connection from '141.168.10.80'. Info: Aborting the procedure due to signal '1'. Error: Aborting session with 'Unable to open display 'nx/nx,options=/root/.x2go/C-root-51-1402520526_stRWWWBROWSER_dp24/options:51''. Session: Aborting session at 'Wed Jun 11 23:02:19 2014'. Session: Session aborted at 'Wed Jun 11 23:02:19 2014'.

My first guess is/was that there's something endianess-related going wrong, as he's running X2Go on a ppc64 architecture instead of x86/x64. However, the fact that the two "wrong" IPs change at random speak against that, so I may be totally wrong with this and there's a much simpler reason and solution.

quoting myself, replying to Mike Gabriel there:

...

Do you think you could at least give him a hint as to where that message is pulling the IP from and how it is being mangled/processed before that?

My guess is that there's some self-made conversion routine somewhere that only works on little-endian architectures like x86 and x64.

PPC64 is big-endian by default.

quoting Mike Gabriel:

you can get the nx-libs sources from git.x2go.org [1] and grep through the sources.

I am currently doing the same to get NX fixed on systems with poly-instantiated /tmp directories.

Here's what I was able to find out so far:

I was able to locate the message in Loop.cpp. It uses the variable "connectedHost". So "connectedHost" contains the wrong IP.

connectedHost gets populated (also in Loop.cpp) like this:

char *connectedHost = inet_ntoa(newAddr.sin_addr);

so either newAddr.sin_addr already contains a wrong value (I'm not sure how to check that, though), or inet_ntoa does something wrong, or both.

I haven't touched C/C++ code since the year 2002 or so, so debugging this further is way beyond my ken.

Any one of the more experienced coders willing to jump in?

Here's some more info about the X2Go server system as provided by Sebastien Chabrolles:

# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 10.7.19.161 fc20-161

# cat /etc/resolv.conf nameserver 129.35.160.4

#cat /etc/nsswitch.conf passwd: files shadow: files group: files ### #this strange-looking entry was present during the first tries. # #hosts: files mdns4_minimal [NOTFOUND=return] dns myhostname # # it was changed to the one below for the last try, which gave # the result with the different, but still wrong, IP. ### hosts: files dns bootparams: nisplus [NOTFOUND=return] files ethers: files netmasks: files networks: files protocols: files rpc: files services: files netgroup: files publickey: nisplus automount: files aliases: files nisplus

# ifconfig -a eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.7.19.161 netmask 255.255.255.0 broadcast 10.7.19.255

    inet6 fe80::f816:3eff:feec:ecb8  prefixlen 64  scopeid

0x20<link> ether fa:16:3e:ec:ec:b8 txqueuelen 1000 (Ethernet)

    RX packets 90677  bytes 5717673 (5.4 MiB)

    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 89102  bytes 32828059 (31.3 MiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 0 (Local Loopback) RX packets 76 bytes 5248 (5.1 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 76 bytes 5248 (5.1 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.7.19.254 0.0.0.0 UG 0 0 0 eth0 10.7.19.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0

• -Stefan

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Power8 support both Endian model (Little and Big)

But Most of the Linux distro on Power are Big Endian (ppc64 is BigEndian) (redhat / fedora) for example.

In my case FC20, we need a code that support Big-Endian or "Endian-safe".

Cordialement / Best Regards

Sébastien Chabrolles Power Systems Benchmark Specialist IBM Client Center, Montpellier 1 rue vieille poste 34000 Montpellier FRANCE Tel +33 4 67 34 40 95 Email : s.chabrolles@fr.ibm.com

From: Stefan Baur <newsgroups.mail2@stefanbaur.de> To: x2go-user@lists.x2go.org Date: 11/06/2014 13:42 Subject: Re: [X2Go-User] Pb with x2go agent on ppc64 system Sent by: x2go-user-bounces@lists.x2go.org

Am 11.06.2014 12:31, schrieb sebastien chabrolles:

Warning: *Refusing connection from '225.3.10.80'.* .80' on port '30003'.

I don't know what is this IP address !!!!!

Neither do I, but is Power8/ppc64 a different-endian architecture than x86? If so, there might be some conversion going on in one of the scripts that isn't "endian-safe", so to speak.

cf. http://en.wikipedia.org/wiki/Endianness

If that turns out to be the problem, I guess we should move the thread to x2go-dev and file a bug about it. Let's see what the others think about the issue ...

Anyone else using X2Go on ppc64? Or on a different-endian system than x86?

-Stefan

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