Manual:SNMP

Applies to RouterOS: v5

Overview

Standards: RFC 1157 RFC 3414 RFC 3416
Package: system

Simple Network Management Protocol (SNMP) is an Internet-standard protocol for managing devices on IP networks. SNMP can be used to graph various data with tools such as CACTI, MRTG or The Dude

SNMP write support is only available for some OIDs. For supported OIDs SNMP v1, v2 or v3 write is supported

Note: SNMP will respond to the query on the interface SNMP request was received from forcing responses to have same source address as request destination sent to the router

Note: SNMP tool collects data from different services running on the system. If, for some reason, communication between SNMP and some service is taking longer time than expected (30 seconds per service, 5 minutes for routing service), you will see a warning in the log stating "timeout while waiting for program". After that, this service will deny SNMP requests for a while before even trying to get requested data again. This error has nothing to do with SNMP service itself. In most cases, such an error is printed when some slow or busy service is monitored through SNMP, and quite often, it is a service that should not be monitored through SNMP, and proper solution in such cases is to skip such OIDs on your monitoring tool.

Quick Configuration

To enable SNMP in RouterOS:

[admin@MikroTik] /snmp> print 
       enabled: no
       contact: 
       location: 
       engine-id: 
       trap-community: (unknown)
       trap-version: 1
[admin@MikroTik] /snmp>  set enabled yes

You can also specify administrative contact information in the above settings. All SNMP data will be available to communities configured in community menu.

General Properties

Sub-menu: /snmp

This sub menu allows to enable SNMP and to configure general settings.

Property	Description
contact (string; Default: "")	Contact information
enabled (yes | no; Default: no)	Used to disable/enable SNMP service
engine-id (string; Default: "")	for SNMP v3, used as part of identifier. You can configure suffix part of engine id using this argument. If SNMP client is not capable to detect set engine-id value then this prefix hex have to be used 0x80003a8c04
location (string; Default: "")	Location information
trap-community (string; Default: public)	Which communities configured in community menu to use when sending out the trap.
trap-generators (interfaces | start-trap; Default: )	What action will generate traps: interfaces - interface changes; start-trap - snmp server starting on the router
trap-interfaces (string | all; Default: )	List of interfaces that traps are going to be sent out.
trap-target (list of IP/IPv6; Default: 0.0.0.0)	IP (IPv4 or IPv6) addresses of SNMP data collectors that have to receive the trap
trap-version (1|2|3; Default: 1)	Version of SNMP protocol to use for trap
src-address (IPv4 or IPv6 address; Default: ::)	Force the router to always use the same IP source address for all of the SNMP messages

Note: engine-id field holds the suffix value of engine-id, usually SNMP clients should be able to detect the value, as SNMP values, as read from the router. However there is a possibility that this is not the case. In which case, the engine-ID value has to be set according to this rule: <engine-id prefix> + <hex-dump suffix>, so as an example, if you have set 1234 as suffix value you have to provide 80003a8c04 + 31323334, combined hex (the result) is 80003a8c0431323334

Community Properties

Sub-menu: /snmp community

This sub-menu allows to set up access rights for the SNMP data.

There is little security in v1 and v2c, just Clear text community string („username“) and ability for Limiting access by IP adress.

In production environment SNMP v3 should be used as that provides security - Authorisation (User + Pass) with MD5/SHA1, Encryption with DES (and since v6.16, AES).

[admin@MikroTik] /snmp community> print value-list 
                     name: public
                  address: 0.0.0.0/0
                 security: none
              read-access: yes
             write-access: no
  authentication-protocol: MD5
      encryption-protocol: DES
  authentication-password: *****
      encryption-password: *****

Warning: Default settings only have one community named public without any additional security settings. These settings should be considered insecure and should be adjusted according required security profile.

Properties

Property	Description
address (IP/IPv6 address; Default: 0.0.0.0/0)	Addresses from which connections to SNMP server is allowed
authentication-password (string; Default: "")	Password used to authenticate connection to the server (SNMPv3)
authentication-protocol (MD5 | SHA1; Default: MD5)	Protocol used for authentication (SNMPv3)
encryption-password (string; Default: "")	password used for encryption (SNMPv3)
encryption-protocol (DES | AES; Default: DES)	encryption protocol to be used to encrypt the communication (SNMPv3). AES (see rfc3826) available since v6.16.
name (string; Default: )
read-access (yes | no; Default: yes)	Whether read access is enabled for this community
security (authorized | none | private; Default: none)
write-access (yes | no; Default: no)	Whether write access is enabled for this community. Read more >>

Management information base (MIB)

The Management Information Base (MIB) is the database of information maintained by the agent that the manager can query. You can download the latest MikroTik RouterOS MIB file from here: www.mikrotik.com/downloads

MIBs used in RouterOS v6.x:

• MIKROTIK-MIB
• MIB-2
• HOST-RESOURCES-MIB
• IF-MIB
• IP-MIB
• IP-FORWARD-MIB
• IPV6-MIB
• BRIDGE-MIB
• DHCP-SERVER-MIB
• CISCO-AAA-SESSION-MIB
• ENTITY-MIB
• UPS-MIB
• SQUID-MIB

Object identifiers (OID)

Each OID identifies a variable that can be read via SNMP. Although the MIB file contains all the needed OID values, you can also print individual OID information in the console with the print oid command at any menu level:

[admin@MikroTik] /interface> print oid

Flags: D - dynamic, X - disabled, R - running, S - slave 
 0  R  name=.1.3.6.1.2.1.2.2.1.2.1 mtu=.1.3.6.1.2.1.2.2.1.4.1 
       mac-address=.1.3.6.1.2.1.2.2.1.6.1 admin-status=.1.3.6.1.2.1.2.2.1.7.1 
       oper-status=.1.3.6.1.2.1.2.2.1.8.1 bytes-in=.1.3.6.1.2.1.2.2.1.10.1 
       packets-in=.1.3.6.1.2.1.2.2.1.11.1 discards-in=.1.3.6.1.2.1.2.2.1.13.1 
       errors-in=.1.3.6.1.2.1.2.2.1.14.1 bytes-out=.1.3.6.1.2.1.2.2.1.16.1 
       packets-out=.1.3.6.1.2.1.2.2.1.17.1 discards-out=.1.3.6.1.2.1.2.2.1.19.1 
       errors-out=.1.3.6.1.2.1.2.2.1.20.1 

Traps

SNMP traps enable router to notify data collector of interface changes and SNMP service status changes by sending traps. It is possible to send out traps with security features to support SNMPv1 (no security). SNMPv2 and variants and SNMPv3 with encryption and authorization.

For SNMPv2 and v3 you have to set up appropriately configured community as a trap-community to enable required features (password or encryption/authorization)

SNMP write

Since RouterOS v3, SNMP write is supported for some functions. SNMP write allows to change router configuration with SNMP requests. Consider to secure access to router or to router's SNMP, when SNMP and write-access are enabled.

To change settings by SNMP requests, use the command below to allow SNMP write for the selected community, Write-access option for SNMP is available from v3.14,

/snmp community set <number> write-access=yes

System Identity

It's possible to change router system identity by SNMP set command,

snmpset -c public -v 1 192.168.0.0 1.3.6.1.2.1.1.5.0  s New_Identity

• snmpset - SNMP application used for SNMP SET requests to set information on a network entity;
• public - router's community name;
• 192.168.0.0 - IP address of the router;
• 1.3.6.1.2.1.1.5.0 - SNMP value for router's identity;

SNMPset command above is equal to the RouterOS command,

/system identity set identity=New_Identity

Reboot

It's possible to reboot the router with SNMP set commamd, you need to set value for reboot SNMP settings, which is not equal to 0,

snmpset -c public -v 1 192.168.0.0 1.3.6.1.4.1.14988.1.1.7.1.0 s 1

• 1.3.6.1.4.1.14988.1.1.7.1.0, SNMP value for the router reboot;
• s 1, snmpset command to set value, value should not be equal to 0;

Reboot snmpset command is equal to the RouterOS command,

/system reboot

Run Script

SNMP write allows to run scripts on the router from system script menu, when you need to set value for SNMP setting of the script,

 
snmpset -c public -v 1 192.168.0.0 1.3.6.1.4.1.14988.1.1.8.1.1.3.X s 1

• X, script number, numeration starts from 1;
• s 1, snmpset command to set value, value should not be equal to 0;

The same command on RouterOS,

/system script> print 
Flags: I - invalid 
 0   name="test" owner="admin" policy=ftp,reboot,read,write,policy,
test,winbox,password,sniff last-started=jan/01/1970
01:31:57 run-count=23 source=:beep 

/system script run 0

Runing scripts with GET

It is possible to run /system scripts via SNMP GET request of the script OID (since 6.37). For this to work SNMP community with write permission is required. OIDs for scripts can be retrieved via SNMPWALK command as the table is dynamic.

Add script:

/system script
add name=script1 owner=admin policy=ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon source=\
   "/sy reboot "
add name=script2 owner=admin policy=ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon source=\
   "[:put output]"

Get the script OID table

$ snmpwalk -v2c -cpublic 192.168.88.1 1.3.6.1.4.1.14988.1.1.8
iso.3.6.1.4.1.14988.1.1.8.1.1.2.1 = STRING: "script1"
iso.3.6.1.4.1.14988.1.1.8.1.1.2.2 = STRING: "script2"
iso.3.6.1.4.1.14988.1.1.8.1.1.3.1 = INTEGER: 0
iso.3.6.1.4.1.14988.1.1.8.1.1.3.2 = INTEGER: 0

To run script use table 18

$ snmpget -v2c -cpublic 192.168.88.1 1.3.6.1.4.1.14988.1.1.18.1.1.2.2
iso.3.6.1.4.1.14988.1.1.18.1.1.2.2 = STRING: "output"

See Also

• SNMP MRTG

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