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NAS-Port is one of the basic RADIUS attributes.

Table of Contents

NAS-Port meaning per Vendor

This section was populated by knowledge accumulated while trying to support various vendor's equipment in 802.1X / MAC-Authentication in the PacketFence open-source Network Access Control.

Refer to PacketFence's source code for the most accurate values.

Wired switches

NAS-Port to ifIndex conversions


The below worked for the Switch 4200G, E4800G and E5500G. They are now branded as HP's.

Here, 4096 NAS-Port slots are reserved per physical port and there is a starting offset of 16781312.

dot1dPort = ceil ( (NAS-Port - 16781312) / 4096 )

dot1dPort is convertible into ifIndex using SNMP (A3COM-HUAWEI-LswINF-MIB::hwifXXBasePortIndex or

Ex: 16855041 is ifIndex 4227289 (dot1dPort 19)

Cisco 2950 and derivatives

IfIndex = NAS-Port - 50000

Ex: 50017 is ifIndex 17

Cisco 2960 and derivatives

IfIndex = NAS-Port - 40000

Ex: 50023 is ifIndex 10023


NAS-Port's number is the ifIndex index.

Ex: NAS-Port 115 is the 115th ifIndex entry which is ifIndex 598.

Wireless controllers or access points

NAS-Port values have not proven meaningful or useful on Wireless equipment. Management type tasks are often performed using an end-point's MAC address instead of a virtual port id.