Hi there,
I'm facing the same problem right now, I'll try to give as much valuable informations as I can.
This is a fresh (1 month) installed server.
* OS: CentOS release 5.5 (Final)
* Zimbra: Release 6.0.8_GA_2661.RHEL5_20100820021155 CentOS5 NETWORK edition.
* no iptables installed
Every few minutes the Nagios server goes wild and warns me that some Zimbra services are down.
- Tests with telnet from the client to any zimbra port confirm the issue.
- The problem lasts for like 1 minute and then goes back to normal.
- Only the client suffers from non responsive server.
- Other hosts in the same LAN can access without any problem (unless I try to connect too often).
tcpdump on zimbra server of the problem (port 110)
Code:
[root@zimbra log]# tcpdump port 110
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
11:48:17.775082 IP nagios.domain.tld.58137 > zimbra.domain.tld.pop3: S 2582162921:2582162921(0) win 5840 <mss 1380,sackOK,timestamp 661513095 0,nop,wscale 6>
11:48:20.771473 IP nagios.domain.tld.58137 > zimbra.domain.tld.pop3: S 2582162921:2582162921(0) win 5840 <mss 1380,sackOK,timestamp 661513845 0,nop,wscale 6>
11:48:26.770916 IP nagios.domain.tld.58137 > zimbra.domain.tld.pop3: S 2582162921:2582162921(0) win 5840 <mss 1380,sackOK,timestamp 661515345 0,nop,wscale 6>
This proves that Zimbra is receiving the packets but does not transfer them to the service because nothing changes in file /opt/zimbra/log/mailbox.log
Don't know what's going on here.
I suspect Zimbra to block access from clients if too many connections are made, (or maybe too many opened connection at the same time?)
Some advice is needed. I would like to monitor my server without being waken up at night for nothing :P
Sam