The Simple Network Management Protocol (SNMP) is a useful tool for remotely managing network devices.
Since it can be used to reconfigure devices, SNMP traffic should be blocked at the organization’s firewall.
Using a VPN with encryption or some type of Tunneling software would be highly recommended in this case.
Source: STREBE, Matthew and PERKINS, Charles, Firewalls 24seven, Sybex 2000, Chapter 4: Sockets and Services from a Security Viewpoint.