Overview

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.

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 the community menu.

General Properties

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

Community Properties

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 the ability for Limiting access by IP address.

In the production environment, SNMP v3 should be used as that provides security - Authorization (User + Pass) with MD5/SHA1, Encryption with DES and 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: *****

Properties

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

Used MIBs in RouterOS:

• 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 the router to notify the 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 an appropriately configured community as a trap-community to enable required features (password or encryption/authorization).

SNMP write

SNMP write allows changing router configuration with SNMP requests. Consider securing access to the 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 to write for the selected community.

/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 command, you need to set the 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 running scripts on the router from the system script menu when you need to set value for the 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, the 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

Running 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 the 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 the 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"