Port 4303Simple Railroad Command Protocol (SRCP)

SRCP lets model-railroad software communicate with digital command stations and control trains and track accessories.

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

also known as srcp, srcpd

Technical Details

what runs on :4303

SRCP is a text-based client/server protocol for model railway control, registered on TCP and UDP port 4303. A client connects to an SRCP server, negotiates a protocol version and session mode, then exchanges commands and responses to query or control railway equipment. TCP is the common connection style; the protocol is not encrypted.

Security Information

exposure of :4303

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 2.6 across 1,515 ports — this one sits 2.4 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

SRCP commands can operate locomotives and track accessories, so an exposed server may let an untrusted network user interfere with a layout. Traffic is plaintext; keep the service on a trusted, segmented network and do not expose it directly to the internet.

Record

iana registry entry

port: :4303
service: Simple Railroad Command Protocol (SRCP)
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 5/10caution
category: Network Services IoT
usage: This port is used by SRCP servers, such as srcpd, to connect model-railroad control software to digital command stations. Engineers are most likely to encounter it on a private network in a model railway setup.
lookups: 0rank 993
added: 2026-10-04
updated: 2026-10-04
references: IANA service name registry — port 4303

Something wrong?

This record is maintained by the engineers who use port 4303. 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 2026-10-04.

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

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :4303Simple Railroad Command Protocol (SRCP)

Technical Details

Security Information

Related Ports

Port 4303Simple Railroad Command Protocol (SRCP)