Port 165Xerox Courier

Xerox Courier RPC traffic for legacy Xerox Network Systems environments.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

also known as xns-courier

Technical Details

what runs on :165

Courier provides typed client/server remote procedure calls over XNS, with clients sending procedure requests and servers returning results or errors. This assignment uses both TCP and UDP port 165; the protocol is generally encountered as legacy XNS application traffic rather than as a modern Internet RPC service. Courier's data encoding and call semantics are defined by the Xerox Courier protocol, while the underlying transport and connection behavior depend on whether the deployment uses TCP or datagram transport.

Security Information

exposure of :165

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 3.2 across 863 ports — this one sits 1.2 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

tcp · udp

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

security overview

Courier traffic is not encrypted by default, and legacy implementations may expose callable services or disclose sensitive data if reachable by untrusted hosts. It should normally be restricted to a trusted legacy XNS network and blocked at Internet boundaries; its rarity substantially limits opportunistic scanning, but does not make an exposed implementation safe.

Record

iana registry entry

port: :165
service: Xerox Courier
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services System
usage: Xerox Courier is the remote procedure call protocol used by Xerox Network Systems (XNS) services. Engineers are most likely to encounter it on legacy Xerox workstations, servers, or network appliances rather than on contemporary public-facing systems; IANA lists the assignment under Xerox and Susie Armstrong 2.
lookups: 0rank 994
added: 2026-08-30
updated: 2026-08-30
references: IANA service name registry — port 165

Something wrong?

This record is maintained by the engineers who use port 165. 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 2026-08-30.

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edit this record →back to the registry

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all 863 in network services →

the 8 most looked-up other ports in network services — 863 ports carry that label.

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :165Xerox Courier

Technical Details

Security Information

Related Ports

Port 165Xerox Courier