Port 4191Dual-Stack MIPv6 NAT Traversal

UDP transport for Dual-Stack Mobile IPv6 signaling and tunneled traffic across IPv4 NATs.

transport: udp
in transit: encrypted
assignment: official
risk: 2/10
lookups: 0

also known as dsmipv6, Dual-Stack Mobile IPv6, RFC 5555

Technical Details

what runs on :4191

DSMIPv6 uses UDP port 4191 to encapsulate Mobile IPv6 signaling and tunneled IPv6 traffic between a mobile node and its home agent when IPv4 transport or NAT traversal is required. The protocol exchanges Mobile IPv6 binding-management messages over the UDP path and maintains the mapping with mobility signaling and, where needed, keepalive behavior; it is not a generic application protocol with a text command handshake. IPsec protection is used for Mobile IPv6 signaling and traffic in normal deployments, while UDP ports 500 and 4500 may also appear for IKE and conventional IPsec NAT traversal.

Security Information

exposure of :4191

risk score

2/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

in transit

encrypted

payloads are protected on the wire

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

An exposed endpoint may receive unsolicited DSMIPv6 signaling or encapsulated traffic, but a correctly configured home agent should require authenticated Mobile IPv6/IPsec peers and reject unauthorised bindings. It is generally not intended as a public application service; restrict it to expected mobility peers and monitor unusual UDP 4191 traffic, malformed encapsulation, and excessive binding or keepalive requests.

Record

iana registry entry

port: :4191
service: Dual-Stack MIPv6 NAT Traversal
transport: UDP
encryption: tls / encrypted
assignment: iana registered
risk: 2/10safe
category: uncategorised
usage: Port 4191 is used by Dual-Stack Mobile IPv6 (DSMIPv6) mobile nodes and home agents to traverse IPv4 networks and NAT gateways. Engineers typically encounter it in cellular or mobility deployments supporting IPv6 mobility over IPv4 access networks.
lookups: 0rank 994
added: 2026-09-06
updated: 2026-09-06
references: IANA service name registry — port 4191
RFC 5555

Something wrong?

This record is maintained by the engineers who use port 4191. 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 2026-09-06.

01edit any field on a page of its own
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edit this record →back to the registry

Related Ports

browse categories →

ports registered around :4191, by lookups.

port	service	proto	category	risk	views
:4201	TinyMUD	TCP	Gaming	caution	7.7k
:4226	Aleph One Game	TCPUDP	Gaming	caution	7.5k
:4224	Cisco Audio Tunneling	TCP	Network Services	caution	6.6k
:4132	NUTS Daemon	TCPUDP	System	safe	0
:4128	NuFW	TCPUDP	Security	safe	0
:4127	NetUniKeyServer	TCPUDP	Network Services	safe	0
:4133	NUTS BOOTP Server	TCPUDP	Network Services	safe	0
:4129	NuFW authentication protocol	TCPUDPtls	Security	caution	0

risk mix of the 8 listed

safe50%
caution50%

1 of 8 encrypted

Port :4191Dual-Stack MIPv6 NAT Traversal

Technical Details

Security Information

Related Ports

Port 4191Dual-Stack MIPv6 NAT Traversal