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i'm using centos 5.7. my ip address is 192.35.251.225. when i start and login to my machine, i'm still on the network in which i'm still reachable on the ipmsg of our company. but after a few hours or so, i can no longer be accessible via ipmsg. on my local, my ip address displayed on the ipmsg is 127.0.0.1 and there's 0 member when i refreshed ipmsg. when i execute

ifconfig eth0

the ip address is still there

inet addr:192.35.251.225

i have tried restarting my network

/sbin/service network restart

but still, i'm not connected to our company's network. this problem occurs when i'm doing a project which is to setup snmp service to another machine which a 64-bit machine so i was connecting to that machine via ssh. then i also execute restoreocon -Rv . on my local machine.

what should i do to solve this problem? any idea what's the cause of this one? please help.

btw, i have checked the /var/log/messages and i have this message

Can't open system message bus connection: Failed to connect to socket 
/var/run/dbus/system_bus_socket: Connection refused
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this issue has something to do with the iptables. although stopping iptables service is not a good habit but it solves the problem. i think i have to flush all the rules in the iptables and add new rules that are important including the 2425 port. –  terrence Jan 19 '12 at 6:56
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1 Answer

TL;DR It could be a company's firewall that blocks ipmsg communication after a time of inactivity.

Detailed: ipmsg depends upon UDP port 2425 (and TCP for attachment transfer). If there is a network device between you and your peer that performs network address translation (NAT) chances are that you simply fall off the conntrack table because of insufficient activity. This table becomes overfilled with tracked hosts (including UDP, as much as it is a connectionless protocol). From your question it seems that you are disconnected after some time of ipmsg inactivity.

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hey, thanks for your answer. actually, i already have added port 2425 both TCP and UDP to my iptables to be accepted. that's why i don't know what's the problem here since 2425 is accepted based on my iptables configuration. –  terrence Jan 19 '12 at 1:58
    
I didn't say anything about iptables. It's about conntrack - are you sure there is no NAT on the way between you and your peer? –  kubanczyk Jan 19 '12 at 9:02
    
oh, sorry. i thought it was iptables that goes wrong here. hmm..actually i don't know anything about that conntrack thing. –  terrence Jan 20 '12 at 1:58
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