LinuxQuestions.org
Download your favorite Linux distribution at LQ ISO.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Networking
User Name
Password
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.

Notices


Reply
  Search this Thread
Old 03-08-2014, 03:54 PM   #1
wsopko
LQ Newbie
 
Registered: Jan 2014
Posts: 3

Rep: Reputation: Disabled
Network connectivity problem - Debian 6 server


I'm having a problem with a Debian 6 server where it looses network connectivity and doesn't come back (server does not respond to pings, and can't connect to any services). The problem happens sporadically. Some times it will go a month without the problem occurring, while other times it will happen within a few days of being rebooted.

When logged into the console, I confirm that the server doesn't seem to have network conectivity (can't ping 8.8.8.8 for example). All services are running though (mysql, Apache, SSH, etc).

When the problem happens, the network interfaces are up (I checked ifconfig, all interfaces looked normal). I also check iptables, and verify there were no rules that would block anything. I also try running /etc/init.d/networking/restart, but that does not fix the problem. The only thing I've found that fixes the problem is rebooting.

The server is a virtual machine with a wired connection in a data centre. The company I rent the server from thinks the problem is due to high RAM usage. They said that the server was frozen due to resource exhaustion and the server stopped responding to ICMP requests, referencing this:

======
root@vm2:~# free -m
total used free shared buffers cached
Mem: 8181 7816 365 0 364 6201
-/+ buffers/cache: 1250 6931
Swap: 8191 0 8191
======

Do you think that high RAM usage could have anything to do with this problem? I think it is something else, but I don't know what else to check.
 
Old 03-09-2014, 08:25 PM   #2
Ser Olmy
Senior Member
 
Registered: Jan 2012
Distribution: Slackware
Posts: 3,348

Rep: Reputation: Disabled
A low memory condition should eventually trigger the kernel oomkiller, but that will only affect processes running on the server, and never something as basic as network connectivity.

Did you try pinging the gateway? Was there an entry for the gateway in the ARP cache when this happened?

Anything in the logs immediately prior to and after network connectivity was lost?
 
Old 03-11-2014, 12:23 AM   #3
wsopko
LQ Newbie
 
Registered: Jan 2014
Posts: 3

Original Poster
Rep: Reputation: Disabled
Quote:
Originally Posted by Ser Olmy View Post
A low memory condition should eventually trigger the kernel oomkiller, but that will only affect processes running on the server, and never something as basic as network connectivity.

Did you try pinging the gateway? Was there an entry for the gateway in the ARP cache when this happened?

Anything in the logs immediately prior to and after network connectivity was lost?
I didn't try pinging the gateway. I'll try that the next time the problem happens, thanks for the idea.

The last thing in /var/log/messages was some apache entries like this:

Mar 8 23:49:57 hostname drupal: http://www.hostname.com|1394347797|m...||0||Retrieved ne
w CAPTCHA#012#012Request: POST http://rest.mollom.com/v1/captcha#012 type = 'image'#012 ssl = 0#012#012Request headers:#012 Accept = 'application/x
ml, application/json;q=0.8, */*;q=0.5'#012 Content-Type = 'application/x-www-form-urlencoded'#012 Authorization = 'OAuth oauth_consumer_key="079943c
bb7a9d6141e0d49fb8700de78", oauth_version="1.0", oauth_nonce="58fda8a94d1f9ed0d9f26c864f0aab4b", oauth_timestamp="1394347796", oauth_signature_method=
"HMAC-SHA1", oauth_signature="Ica0u1rFipmFj%2FctiNrWHpoXjrw%3D"'#012#012Response: 200 #012 code = '200'#012 captcha =#012 id = '14030919d19a4dbbc
6'#012 url = 'http://173.192.235.120:80/v1/captcha/14030919d19a4dbbc6.png'#012#012Retrieved new CAPTCHA

After the network connection is lost, there is not much in the logs, but I can see that things are still running. Cron is still processing (runs an ISPConfig update script every 2 minutes), named is complaining that the network is unreachable when trying to resolve hostnames, and the postfix mailq is being run (all attempts from previously queued mail gets set back to deferred due to domain names not being found).
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Debian 6 VM server - network connectivity problem wsopko Linux - Server 0 01-09-2014 09:45 PM
Debian Lenny server, no connectivity to network after reboot neilgunton Linux - Networking 3 08-24-2010 11:04 AM
[SOLVED] Network server (DHCP) and connectivity problems lpallard Linux - Networking 13 06-06-2010 07:34 PM
Server should shutdown when network connectivity goes down. rhizopod Linux - Server 1 10-20-2009 01:22 AM
RHEL 5 server network connectivity very strange bajones Linux - Networking 7 06-25-2008 02:30 AM

LinuxQuestions.org > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 05:55 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration