UDP 1645
Synopsis
- UDP port 1645 is the legacy RADIUS Authentication port used before IANA standardized 1812; many products still support it for backward compatibility.
- Livingston/Lucent (Ascend) PortMaster RADIUS servers originally listened on 1645 (auth) and 1646 (accounting).
- FreeRADIUS can be configured to listen on 1645 for authentication.
- Microsoft IAS/NPS (Windows Server) supports alternate RADIUS ports and can use 1645 to interoperate with older clients.
- Cisco Secure ACS and Cisco ISE allow configurable RADIUS ports and can accept or originate RADIUS on 1645; Cisco ASA and other Cisco NAS/VPN gear can target 1645.
- Juniper/Funk Steel-Belted RADIUS and Juniper NetScreen/SSG devices support 1645 for legacy RADIUS authentication.
- Aruba Mobility Controllers and HP ProCurve/Aruba switches can be configured to use RADIUS auth on 1645 for older server compatibility.
- Security: Internet-exposed RADIUS on UDP/1645 is routinely scanned and targeted for credential/shared-secret brute forcing, and misconfigured servers have been abused for UDP reflection/amplification.
Observed activity
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