Port 1812RADIUS Auth Protocol
The RADIUS (Remote Authentication Dial-In User Service) protocol is a security protocol primarily used to provide centralized Authentication and Authorization services for users attempting to access a network. It facilitates the validation of user credentials and determines user permissions before granting access. Widely adopted by ISPs and enterprise WLANs, RADIUS enables scalable and secure user management across various network access servers..
- transport
- tcp · udp
- in transit
- cleartext
- assignment
- official
- risk
- 4/10
- lookups
- 11,985
2 transports registered
payload readable on path
registered with iana
caution
rank 330 of 993 · top 33%
Technical Details
what runs on :1812RADIUS, specified in RFC 2865, is a client/server protocol that operates on port 1812 over both UDP and TCP. It acts as a centralized service for managing user authentication and authorization for network access. Network devices like VPN concentrators, wireless access points, or switches act as RADIUS clients by forwarding user credentials to the RADIUS server, which validates them against a user database or identity provider.
Typically, a RADIUS exchange involves an Access-Request from the client with user credentials in response to which the server sends an Access-Accept or Access-Reject, depending on the verification outcome. The protocol supports attribute-value pairs allowing flexible policy enforcement and granular authorization control through vendor-specific attributes.
RADIUS is designed to work efficiently across large-scale infrastructures, supporting roaming and multiple access technologies. While originally over UDP for lightweight communication, modern implementations frequently support TCP or even TLS-secured variants (RadSec) to address reliability and security concerns.
Security Information
exposure of :1812risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
security averages 3.8 across 216 ports — this one sits 0.2 above.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
official
registered with iana for this service — scanners fingerprint it by number
reachable over
tcp · udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
Common vulnerabilities of RADIUS implementations include:
- Susceptibility to credential interception if used without secure tunneling (plaintext credentials over UDP)
- Weak shared secret keys, which can be brute-forced
- Vulnerabilities in poorly configured or outdated RADIUS servers
- Lack of encryption for attribute data in transit, exposing sensitive info
Key mitigations are:
- Deploying RADIUS over secure tunnels such as IPsec or leveraging RadSec (RADIUS over TLS)
- Using strong shared secrets and complex passwords
- Regularly updating RADIUS server software and applying security patches
- Enabling logging and monitoring for suspicious authentication activity
- Restricting access to the RADIUS server through network segmentation and access controls
- Implementing multi-factor authentication to reduce reliance on password security alone
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risk mix of the 8 listed
- caution100%
3 of 8 encrypted