Configuring UDP Ports

The transaction-based RADIUS protocol uses two UDP ports: one for authentication packets and one for accounting packets. The ports must be configured on two sides: the Merit AAA server and the RADIUS clients (SDX software and JUNOSe router).

The officially assigned UDP port numbers are:

• 1812 for authentication
• 1813 for accounting

Early deployments of RADIUS used 1645/udp for authentication packets and 1646/udp for accounting packets.

The Merit AAA RADIUS server uses the latter ports by default, whereas the JUNOSe router uses the official ports by default.

There are two possible ways to change these settings:

• You can change these defaults by editing your copy of the /etc/services file to contain two entries for RADIUS authentication and accounting service that specify the ports you wish to use. Add the following two lines to the /etc/services file:

• radius 1812/udp # RADIUS Authentication    
• radacct 1813/udp # RADIUS Accounting

• You can override all default and configured values at server start-up with the radiusd -p and radiusd -q command line options. The SDX software installs the Merit AAA server with a start script, called rad, which uses ports 1812 and 1813 for authentication and accounting (see next section).