Port 5091Context Transfer Protocol (CXTP)

CXTP transfers network-session context between access routers to support faster handoffs; it is rarely encountered on public networks.

inNetwork Services Mobile

transport: sctp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

Technical Details

what runs on :5091

IANA assigns SCTP port 5091 to CXTP. The protocol’s documented purpose is to transfer context—such as session-related state—between access routers during a handoff, using request, transfer, and acknowledgment exchanges. The published CXTP specification describes UDP transport on port 5091; the SCTP registry entry does not by itself establish a common SCTP wire profile or deployment. A listener using SCTP would first establish an SCTP association, but its CXTP framing and interoperability should not be assumed from the port assignment alone.

Security Information

exposure of :5091

risk score

2/ 10safe

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

network services averages 2.6 across 1,620 ports — this one sits 0.6 below.

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

sctp

every listening transport is another surface to filter at the edge

security overview

CXTP is meant for communication between trusted network mobility infrastructure, not public clients. Transferred context may be sensitive, and forged or replayed messages could disrupt handoffs or affect session state; the protocol’s security considerations rely on protecting the router-to-router exchange, including with IPsec. This port is rarely observed open, but an unexpected listener should be identified and restricted to trusted peers.

Record

iana registry entry

port: :5091
service: Context Transfer Protocol (CXTP)
transport: SCTP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services Mobile
usage: CXTP is intended for mobility handoffs, where an old access router transfers session state to a new one so services can continue with less interruption. It is a niche network-infrastructure protocol, not a service commonly found on ordinary internet-facing hosts.
lookups: 0rank 993
added: 2026-10-07
updated: 2026-10-07
references: IANA service name registry — port 5091
RFC 4065

Something wrong?

This record is maintained by the engineers who use port 5091. 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 2026-10-07.

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edit this record →back to the registry

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :5091Context Transfer Protocol (CXTP)

Technical Details

Security Information

Related Ports

Port 5091Context Transfer Protocol (CXTP)