Port 12003IBM Enterprise Extender SNA COS Medium Priority

IBM Enterprise Extender traffic for SNA Class of Service medium-priority flows.

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

also known as entextmed, SNA COS Medium Priority

Technical Details

what runs on :12003

Enterprise Extender carries SNA and High-Performance Routing traffic inside UDP datagrams, using separate UDP service ports for SNA classes of service. Port 12003 identifies the medium-priority class; related Enterprise Extender ports in the 12000 range serve other priorities. Although IANA lists both TCP and UDP, normal Enterprise Extender operation is connectionless UDP encapsulation rather than a TCP listener, with SNA control and data information carried in the encapsulated payload.

Security Information

exposure of :12003

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 2.7 across 1,440 ports — this one sits 2.3 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

This port should generally be restricted to trusted Enterprise Extender peers and private or VPN-protected networks. Enterprise Extender does not provide encryption by default, so exposed traffic can reveal or carry sensitive SNA sessions; an Internet-reachable endpoint may also permit spoofed or malformed encapsulated traffic to reach SNA infrastructure. Use IPsec, authenticated tunnels, and filtering at the network boundary where traffic crosses untrusted networks.

Record

iana registry entry

port: :12003
service: IBM Enterprise Extender SNA COS Medium Priority
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 5/10caution
category: Network Services System
usage: This port is used by IBM Enterprise Extender to carry medium-priority SNA traffic across an IP network. It is normally encountered between IBM mainframe, VTAM, Communications Server, or SNA gateway systems on private enterprise networks, not as a general Internet service.
lookups: 0rank 993
added: 2026-08-22
updated: 2026-09-22
references: IANA service name registry — port 12003

Something wrong?

This record is maintained by the engineers who use port 12003. 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 2026-09-22.

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 1,440 in network services →

the 8 most looked-up other ports in network services — 1,440 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 :12003IBM Enterprise Extender SNA COS Medium Priority

Technical Details

Security Information

Related Ports

Port 12003IBM Enterprise Extender SNA COS Medium Priority