CentOS 6.3 Virtual under OpenVZ cannot ping, host lookups, outbound connections while postfix running
- by Paul Cravey
My best theory is that some kernel limit is being hit preventing outbound connections. We have tried basically everything from tcpdumps to provisioning an entirely new virtual server (we do not have this problem on any other virtuals), however the problem somehow carried over, even with new postfix build (working).
Emails work, and outbound connections work, so long as postfix does not have too much going on. /proc/user_beancounters shows no limits being hit (show below). Nevertheless, pings fail even to IP addresses. TCP stack appears healthy. Load is low. No iowait. Flushed iptables already. Has anyone experienced anything like this?
uid resource held maxheld barrier limit failcnt
3: kmemsize 166216365 170262528 9223372036854775807 9223372036854775807 0
lockedpages 0 0 9223372036854775807 9223372036854775807 0
privvmpages 285727 351885 9223372036854775807 9223372036854775807 0
shmpages 16933 17605 9223372036854775807 9223372036854775807 0
dummy 0 0 0 0 0
numproc 150 303 9223372036854775807 9223372036854775807 0
physpages 314156 326191 0 1280000 0
vmguarpages 0 0 9223372036854775807 9223372036854775807 0
oomguarpages 165355 165355 9223372036854775807 9223372036854775807 0
numtcpsock 89 172 9223372036854775807 9223372036854775807 0
numflock 22 76 9223372036854775807 9223372036854775807 0
numpty 1 2 9223372036854775807 9223372036854775807 0
numsiginfo 0 75 9223372036854775807 9223372036854775807 0
tcpsndbuf 2733472 4371752 9223372036854775807 9223372036854775807 0
tcprcvbuf 1798336 5427296 9223372036854775807 9223372036854775807 0
othersockbuf 491120 1000760 9223372036854775807 9223372036854775807 0
dgramrcvbuf 0 238728 9223372036854775807 9223372036854775807 0
numothersock 361 505 9223372036854775807 9223372036854775807 0
dcachesize 135941831 136114679 9223372036854775807 9223372036854775807 0
numfile 2905 4990 9223372036854775807 9223372036854775807 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
numiptent 8 9 9223372036854775807 9223372036854775807 0
[root@bni /]# ping 4.2.2.1
PING 4.2.2.1 (4.2.2.1) 56(84) bytes of data.
--- 4.2.2.1 ping statistics ---
9 packets transmitted, 0 received, 100% packet loss, time 8493ms
[root@bni /]# service postfix stop
[root@bni /]# ping 4.2.2.1
PING 4.2.2.1 (4.2.2.1) 56(84) bytes of data.
64 bytes from 4.2.2.1: icmp_seq=1 ttl=53 time=8.63 ms
64 bytes from 4.2.2.1: icmp_seq=2 ttl=53 time=8.62 ms
64 bytes from 4.2.2.1: icmp_seq=3 ttl=53 time=8.63 ms
64 bytes from 4.2.2.1: icmp_seq=4 ttl=53 time=8.66 ms
Outbound connections of all sorts fail when postfix is running.