I have a
CentOS release 5.4 linux box on Amazon EC2 that I'm trying to set up to be monitored via Nagios. The machine is in the same security group as the nagios server, but it seems to be unresponsive to pings or NRPE checks, although apparently port 22 is open.
The CentOS box can ping itself using it's internal IP address, and it can ping the Nagios server, but the server can not ping the CentOS box.
I know the CentOS box is using
iptables, here are the contents of the
/etc/sysconfig/iptables file (some ips changed for security):
# Generated by iptables-save v1.3.5 on May 16 11:28:45 2012 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [56:6601] -A INPUT -s 18.104.22.168/255.255.0.0 -p tcp -m tcp --dport 22 -j ACCEPT -A INPUT -s 22.214.171.124 -p tcp -m tcp --dport 22 -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -s 126.96.36.199 -p tcp -m tcp --dport 5666 -j ACCEPT COMMIT # Completed on May 16 11:28:45 2012
The part that really gets me is that even after I do
Flushing firewall rules: [ OK ] Setting chains to policy ACCEPT: filter [ OK ] Unloading iptables modules: [ OK ]
I am still unable to ping the box or do NRPE checks on it.
What else could be preventing
ping or other connections? I'm not sure what else to try.
Here is a list of processes found with
sudo ps -A:
aio/0 atd bash cqueue/0 crond dbus-daemon dhclient events/0 hald hald-runner init kauditd kblockd/0 khelper khubd kjournald kmirrord kmpathd/0 kpsmoused kseriod ksoftirqd/0 kswapd0 kthread master migration/0 mingetty nscd pdflush pickup qmgr sshd su syslog-ng udevd watchdog/0 xenbus xenwatch xinetd