Xrootd and IPv6

ROOT
1

Dear Proofers,
xrootd ( 5.20.00) seems not to work with IPv6:
proof.conf:
worker lx64a68.cos.lrz-muenchen.de
…
The command:

gives:

lx64a68.cos.lrz-muenchen.de has address 10.156.70.68
lx64a68.cos.lrz-muenchen.de has IPv6 address 2001:4ca0:0:200::a9c:4644

In the xrd-log files one gets:

081023 11:21:55 001 xpd : XrdProofWorker::Reset: DNS could not resolve 'lx64a68.cos.lrz-muenchen.de'
Using directly the IP(v4) address: 10.156.70.68
works.
Is there anything one can do about this?
Cheers
Otto

2

Hi Otto,

can you try if for example:

TInetAddress a = gSystem->GetHostByName(" lx64a68.cos.lrz-muenchen.de")
a.Print()

I get:

lx64a68.cos.lrz-muenchen.de/10.156.70.68 (not connected)
Address: 10.156.70.68

do you see the same?

Cheers, Fons.

3

Hi Fons,
logged on e.g. lx64a66.cos.lrz-muenchen.de
I get the same answer:
TInetAddress a = gSystem->GetHostByName(“lx64a68.cos.lrz-muenchen.de”)
root [1] a.Print()
lx64a68.cos.lrz-muenchen.de/10.156.70.68 (not connected)
Address: 10.156.70.68

However I didnt manage in an interactive session
to issue the same command as in: XrdProofWorker.cxx:97
char *fullHostName = XrdNetDNS::getHostName(“lx64a68”,&err);
I tried things like:
gSystem->Load(“libXrdRootd.so”);
gSystem->Load(“libProofx.so”)

Our system is: Linux lx64a66 2.6.16.54-0.2.8-smp , x86_64
SUSE Linux Enterprise Server 10
Cheers
Otto

4

Dear Proofers,

In a interactive session I get:

root [0] TProof* p = TProof::Open("10.156.70.67");
090512 16:11:53 001 Xrd: Connect: can't open connection to [::2001:4ca0:0:200:100:400:1093]
090512 16:11:55 001 Xrd: Connect: can't open connection to [::2001:4ca0:b0f3:9c40:1093]
090512 16:11:57 001 Xrd: Connect: can't open connection to [::176.243.156.64:1093]

I guess somethings goes wrong with IP4 / 6 stuff again.
To debug I would like to do something like this:

   XrdClientDebug * cld = XrdClientDebug::Instance();
   cld->SetLevel(10);

but this does not work in an interactive session, since the XrdXXX is not accessible
from CINT.

Cheers
Otto

5

Hi,

to switch on the debug in the Xrootd client you don’t need to mess up with XrdClientDebug, You can just set the ROOT var XNet.Debug to a value >= 0, where

1->very low verbosity
2->high verbosity
3->trace everything in the data flows and the internal logic
4->like 3, and also dump the byte streams at low level

You can set it by editing your .rootrc file or by using gEnv->SetValue()

When you are able to see the log, please post it, since it is the first time I see such a behavior.
BTW, does it happen also when you just use TFile::Open towards your xrootd redirector?

Fabrizio

6

Hi,

I am working with the same setup as Otto. I have been able to instanciate a PROOF session by using a slightly customed version of ROOT, which I installed from source. I edited the file <root_sources>/net/xrootd/src/xrootd/src/XrdNet/XrdNetDNS.cc in order to force IPv4, using the following code:

myhints.ai_family = AF_INET;

I attached the modified XrdNetDNS.cc file to this post.

Regards,
Philippe
XrdNetDNS.cxx (22 KB)

7

Hi,

FYI, the change in XrdNetDNS.cc to force IPv4 is in the SVN trunk now.

Gerri