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Unable to connect to CentOS Server via SNMP

Votes:

0

I've been working on this for a couple of weeks now. We have a new installation of PRTG, and have yet to successfully connect to our CentOS servers via SNMP.

On the server where we're doing primary work:

[root@nessus ~]# netstat -tulnp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:161             0.0.0.0:*               LISTEN      35964/snmpd
tcp        0      0 127.0.0.1:199           0.0.0.0:*               LISTEN      35964/snmpd
tcp6       0      0 ::1:161                 :::*                    LISTEN      35964/snmpd
udp        0      0 0.0.0.0:161             0.0.0.0:*                           35964/snmpd
udp6       0      0 ::1:161                 :::*                                35964/snmpd

[root@nessus snmp]# cat snmpd.conf
agentAddress udp:161,udp6:[::1]:161,tcp:161,tcp6:[::1]:161
rocommunity public
rwcommunity public
rocommunity "prtg" 10.53.2.208

[root@nessus snmp]# ps -aux | grep snmp
root     35964  0.0  0.3 229140 13136 ?        Ss   Apr30   2:56 /usr/sbin/snmpd -LS0-5d -Lf /dev/null -u root -g root -p /var/run/snmpd.pid -f

[root@nessus snmp]# nmap -sT -O localhost

Starting Nmap 6.47 ( http://nmap.org ) at 2018-05-03 09:13 EDT
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0011s latency).
Other addresses for localhost (not scanned): 127.0.0.1
PORT    STATE SERVICE
25/tcp  open  smtp
161/tcp open  snmp
199/tcp open  smux
Device type: general purpose
Running: Linux 3.X
OS CPE: cpe:/o:linux:linux_kernel:3
OS details: Linux 3.7 - 3.15
Network Distance: 0 hops

Linux  3.10.0-693.17.1.el7.x86_64

From the PRTG Windows server:

----------------------- New Test -----------------------
Paessler SNMP Tester 5.2.3 Computername: PRTG Interface: 10.53.2.208
5/3/2018 9:17:47 AM (45 ms) : Device: 10.53.2.211
5/3/2018 9:17:47 AM (50 ms) : SNMP V2c
5/3/2018 9:17:47 AM (53 ms) : Uptime
5/3/2018 9:17:58 AM (10106 ms) : SNMP Datatype: ASN_PRIMITIVE
5/3/2018 9:17:58 AM (10112 ms) : -------
5/3/2018 9:17:58 AM (10114 ms) : DISMAN-EVENT-MIB::sysUpTimeInstance = No response (check: firewalls, routing, snmp settings of device, IPs, SNMP version, community, passwords etc) (SNMP error # -2003) ( 0 seconds )
5/3/2018 9:18:08 AM (20122 ms) : SNMP Datatype: ASN_PRIMITIVE
5/3/2018 9:18:08 AM (20124 ms) : HOST-RESOURCES-MIB::hrSystemUptime.0 = No response (check: firewalls, routing, snmp settings of device, IPs, SNMP version, community, passwords etc) (SNMP error # -2003) ( 0 seconds )
5/3/2018 9:18:08 AM (20126 ms) : Done


----------------------- New Test -----------------------
Paessler SNMP Tester 5.2.3 Computername: PRTG Interface: 10.53.2.208
5/3/2018 9:18:11 AM (7 ms) : Device: 10.53.2.211
5/3/2018 9:18:11 AM (10 ms) : SNMP V2c
5/3/2018 9:18:11 AM (14 ms) : Custom OID 1.3.6.1.2.1.1.3.0
5/3/2018 9:18:21 AM (10021 ms) : SNMP Datatype: ASN_PRIMITIVE
5/3/2018 9:18:21 AM (10024 ms) : -------
5/3/2018 9:18:21 AM (10026 ms) : Value: No response (check: firewalls, routing, snmp settings of device, IPs, SNMP version, community, passwords etc) (SNMP error # -2003)
5/3/2018 9:18:21 AM (10029 ms) : Done


----------------------- New Test -----------------------
Paessler SNMP Tester 5.2.3 Computername: PRTG Interface: 10.53.2.208
5/3/2018 9:18:24 AM (10 ms) : Device: 10.53.2.211
5/3/2018 9:18:24 AM (14 ms) : SNMP V2c
5/3/2018 9:18:24 AM (19 ms) : Walk 1.3.6.1
5/3/2018 9:18:34 AM (10038 ms) : Error: -2003

centos connectivity linux snmp

Created on May 3, 2018 1:19:12 PM

Last change on May 4, 2018 5:45:54 AM by Stephan Linke [Paessler Support]



2 Replies

Votes:

0

Since CentOS has a firewall up and running which blocks all but SSH and ICMP (iirc) by default, I gotta ask if that has been taken care of? :)

Kind regards,
Stephan Linke, Tech Support Team

Created on May 4, 2018 5:46:57 AM by Stephan Linke [Paessler Support]



Votes:

0

Thanks for that; I won't publish the firewall configuration for security purposes. Kindly add the following line to your snmpd configuration file and reload the snmp daemon: 

rocommunity prtg 10.53.2.208/32
agentAddress  udp:161

That'll open up SNMP in general on the host, but only allow the PRTG server to actually query it.

Kind regards,
Stephan Linke, Tech Support Team

Created on May 11, 2018 6:24:48 AM by Stephan Linke [Paessler Support]




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