Port 521RIPng

RIPng exchanges IPv6 routing information between routers, typically over UDP port 521.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 5/10
lookups: 0

also known as RIP for IPv6, Routing Information Protocol next generation

Technical Details

what runs on :521

RIPng is defined by RFC 2080 and normally uses UDP port 521. Routers send periodic route updates, typically every 30 seconds, and use IPv6 multicast address FF02::9 (the RIP routers group) for exchanges; requests and triggered updates are also supported. Messages contain IPv6 route entries with prefixes, route tags, and metrics, with a maximum metric of 16 indicating an unreachable route. RIPng does not provide encryption or built-in strong authentication, and is distinct from IPv4 RIP on UDP port 520.

Security Information

exposure of :521

risk score

5/ 10caution

worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.

network services averages 3.6 across 695 ports — this one sits 1.4 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

RIPng is intended for controlled routing domains rather than direct Internet exposure. An attacker able to inject or alter RIPng traffic may advertise bogus routes, redirect traffic, or create denial-of-service conditions; filtering and IPv6 infrastructure controls should restrict it to trusted router interfaces.

Record

iana registry entry

port: :521
service: RIPng
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 5/10caution
category: Network Services
usage: RIPng (Routing Information Protocol next generation) is an IPv6 distance-vector routing protocol used primarily inside small networks and autonomous systems. Routers exchange reachability information on port 521; the IANA registry lists both TCP and UDP, but normal RIPng operation uses UDP.
lookups: 0rank 994
added: 2026-08-23
updated: 2026-08-23
references: IANA service name registry — port 521

Something wrong?

This record is maintained by the engineers who use port 521. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-08-23.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

Related Ports

all 695 in network services →

the 8 most looked-up other ports in network services — 695 ports carry that label.

port	service	proto	category	risk	views
:9080	Groove RPC	TCPUDP	Web Services	caution	70.8k
:6543	Jetnet	UDP	Network Services	caution	65.3k
:5938	TeamViewer	TCPUDP	Remote Access	caution	65.0k
:8291	Winbox MikroTik Admin	TCP	Security	caution	62.9k
:3233	WhiskerControl Protocol	TCPUDP	Network Services	caution	61.9k
:3268	Microsoft Global Catalog (GC)	TCPUDP	Security	caution	54.6k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:3128	Tatsoft Default HTTP Proxy	TCP	Web Services	caution	46.8k

risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :521RIPng

Technical Details

Security Information

Related Ports

Port 521RIPng