On Mon, 21 Feb 2005, Dimitris Zilaskos wrote:
> From our site , we can ping and telnet to the RB/BDII in CERN from all
> our nodes , except from our CE ( node001.grid.auth.gr) , which can
> communicate with lxn1188.cern.ch/lxn1182.cern.ch with udp and icmp ,but
> not with TCP.It appears the packets are blocked by a firewall.
This is very interesting observation. And the more interesting thing is,
that we have the exactly same situation on our farms:
on CE (golias25.farm.particle.cz):
[root@golias25 root]# ping -c 1 lxn1189.cern.ch
PING lxn1189.cern.ch (137.138.152.218) from 147.231.25.25 : 56(84) bytes
of data.
64 bytes from lxn1189.cern.ch (137.138.152.218): icmp_seq=1 ttl=46
time=33.0 ms
--- lxn1189.cern.ch ping statistics ---
1 packets transmitted, 1 received, 0% loss, time 0ms
rtt min/avg/max/mdev = 33.094/33.094/33.094/0.000 ms
[root@golias25 root]# telnet lxn1189.cern.ch 2170
Trying 137.138.152.218...
[root@golias25 root]# ping -c 1 lxn1189.cern.ch
PING lxn1189.cern.ch (137.138.152.218) from 147.231.25.25 : 56(84) bytes
of data.
64 bytes from lxn1189.cern.ch (137.138.152.218): icmp_seq=1 ttl=46
time=33.0 ms
--- lxn1189.cern.ch ping statistics ---
1 packets transmitted, 1 received, 0% loss, time 0ms
rtt min/avg/max/mdev = 33.094/33.094/33.094/0.000 ms
[root@golias25 root]# telnet lxn1189.cern.ch 2170
Trying 137.138.152.218...
And here it hangs.
But when I ssh to some workernode, it works as charm:
[root@goliasx44 root]# ping -c 1 lxn1189.cern.ch
PING lxn1189.cern.ch (137.138.152.218) from 147.231.25.44 : 56(84) bytes
of data.
64 bytes from lxn1189.cern.ch (137.138.152.218): icmp_seq=1 ttl=46
time=32.5 ms
--- lxn1189.cern.ch ping statistics ---
1 packets transmitted, 1 received, 0% loss, time 0ms
rtt min/avg/max/mdev = 32.581/32.581/32.581/0.000 ms
[root@goliasx44 root]# telnet lxn1189.cern.ch 2170
Trying 137.138.152.218...
Connected to lxn1189.cern.ch.
Escape character is '^]'.
(tried from a few random worker nodes, everything worked).
The same situation is on our second PRAGUE farm (CE skurut17.cesnet.cz).
Strange situation, indded, isn't it?
--
Jiri Kosina
Institute of Physics, Academy of sciences of the Czech Republic
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