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Old 06-08-2010, 07:16 PM   #1
kopper27
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UDP Port 161


hi guys

My linux server have SNMP configure port by default is 161 (UDP)
now my monitor team - who are using Nagios - say the server are not being monitor

so check netstat -lnu and I see all is OK and snmp service is running fine
what else should I check about this port 161? to see if it is really opened and listening?

thanks a lot
 
Old 06-08-2010, 07:24 PM   #2
carltm
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Try running snmpwalk on that server to make sure that you
get a response. If that works, try running snmpwalk on
the nagios server. If it doesn't work on the nagios
server, run iptables -nL to see if the port is being
blocked. Also check the configuration of the snmp
service, since it may only send responses to select
addresses.
 
Old 06-08-2010, 07:29 PM   #3
kopper27
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Quote:
Originally Posted by carltm View Post
Try running snmpwalk on that server to make sure that you
get a response. If that works, try running snmpwalk on
the nagios server. If it doesn't work on the nagios
server, run iptables -nL to see if the port is being
blocked. Also check the configuration of the snmp
service, since it may only send responses to select
addresses.
I forgot to add the netstat -lun output

Code:
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State

udp        0      0 0.0.0.0:161                 0.0.0.0:*
 
Old 06-08-2010, 07:36 PM   #4
kopper27
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Quote:
Originally Posted by carltm View Post
Try running snmpwalk on that server to make sure that you
get a response. If that works, try running snmpwalk on
the nagios server. If it doesn't work on the nagios
server, run iptables -nL to see if the port is being
blocked. Also check the configuration of the snmp
service, since it may only send responses to select
addresses.
how can I run snmpwalk?

and yes the snmp is configured to send to specified IP
 
Old 06-08-2010, 07:52 PM   #5
TB0ne
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Quote:
Originally Posted by kopper27 View Post
how can I run snmpwalk?
Type in "snmpwalk". Read the man page for more info on the command.
Quote:
and yes the snmp is configured to send to specified IP
It should respond to localhost, or 127.0.0.1 also, so if you run snmpwalk on that machine locally, it'll respond. Might want to check and see if you're running IPtables, or blocking the port somehow.
 
Old 06-08-2010, 08:00 PM   #6
kopper27
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Quote:
Originally Posted by TB0ne View Post
Type in "snmpwalk". Read the man page for more info on the command.

It should respond to localhost, or 127.0.0.1 also, so if you run snmpwalk on that machine locally, it'll respond. Might want to check and see if you're running IPtables, or blocking the port somehow.
no iptables

Code:
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

I mean it was working OK and suddenly 6 servers Stopped working
 
Old 06-08-2010, 09:36 PM   #7
TB0ne
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Quote:
Originally Posted by kopper27 View Post
no iptables

Code:
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

I mean it was working OK and suddenly 6 servers Stopped working
This is much different than your first post, when you said "my linux server" (singular). Would help if you had given complete information in your first post.

One might fail...six don't, unless something changes further downstream, like a router/firewall in between those six and the monitoring server.
 
Old 06-09-2010, 01:48 PM   #8
kopper27
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Quote:
Originally Posted by TB0ne View Post
This is much different than your first post, when you said "my linux server" (singular). Would help if you had given complete information in your first post.

One might fail...six don't, unless something changes further downstream, like a router/firewall in between those six and the monitoring server.
sorry I did not say 6 servers

yeah I told them the same thing before posting here 1 server is OK but 6 having the same issue I told them the only thing shared by all of them is network..

but my networking team is so dump....

yeah it was a networking issue
thanks a lot
 
Old 06-09-2010, 03:57 PM   #9
TB0ne
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Quote:
Originally Posted by kopper27 View Post
sorry I did not say 6 servers

yeah I told them the same thing before posting here 1 server is OK but 6 having the same issue I told them the only thing shared by all of them is network..

but my networking team is so dump....

yeah it was a networking issue
thanks a lot
Really?? They're "dump"??? Or do you mean "dumb"???
 
  


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