Port 257Secure Electronic Transaction

Port 257 was assigned for Secure Electronic Transaction payment messages between merchants, cardholders, and payment gateways.

inWeb Services Security

transport: tcp · udp
in transit: encrypted
assignment: official
risk: 1/10
lookups: 0

also known as set, SET payment protocol

Technical Details

what runs on :257

SET is a certificate-based payment protocol using digital signatures, encrypted payment data, and dual signatures to separate order information from card details. IANA registers the service on both TCP and UDP port 257, although SET deployments commonly used application-layer exchanges over reliable HTTP/TCP transport and related web infrastructure such as ports 80 or 443.

Security Information

exposure of :257

risk score

1/ 10safe

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

web services averages 3.6 across 128 ports — this one sits 2.6 below.

in transit

encrypted

payloads are protected on the wire

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

SET was designed to protect payment information cryptographically and authenticate the participating cardholder, merchant, and payment gateway. Its rarity and legacy status make an exposed listener unusual; restrict it to known payment peers and investigate unexpected traffic rather than assuming that port 257 is a modern payment service.

Record

iana registry entry

port: :257
service: Secure Electronic Transaction
transport: TCPUDP
encryption: tls / encrypted
assignment: iana registered
risk: 1/10safe
category: Web Services Security
usage: This port was assigned to Secure Electronic Transaction (SET), an electronic-commerce payment protocol associated with card networks and payment gateways. SET deployments are now rare; engineers are more likely to encounter the assignment in legacy systems or scans than on a current production service.
lookups: 0rank 994
added: 2026-08-27
updated: 2026-08-27
references: IANA service name registry — port 257

Something wrong?

This record is maintained by the engineers who use port 257. 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 2026-08-27.

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edit this record →back to the registry

Related Ports

all 128 in web services →

the 8 most looked-up other ports in web services — 128 ports carry that label.

port	service	proto	category	risk	views
:8888	Sun Answerbook & Alt HTTP	TCP	Web Services	caution	123.9k
:8000	Intel Remote Desktop / Alternate HTTP Port	TCP	Web Services	safe	84.3k
:8888	NewsEDGE	TCPUDP	Web Services	caution	83.3k
:8888	HTTP Alternative Port	TCP	Web Services	caution	76.5k
:8888	GNUmp3d Streaming HTTP	TCP	Web Services	caution	76.3k
:9080	Groove RPC	TCPUDP	Web Services	caution	70.8k
:8881	Atlasz Secure Server	TCP	Web Services	caution	67.6k
:80	HTTP	TCPUDP	Web Services	caution	67.3k

risk mix of the 8 listed

safe13%
caution88%

0 of 8 encrypted

Port :257Secure Electronic Transaction

Technical Details

Security Information

Related Ports

Port 257Secure Electronic Transaction