Port 1904Fujitsu ICL Terminal Emulator Program C

Port 1904 is assigned to the Fujitsu ICL Terminal Emulator Program C.

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

also known as fjicl-tep-c

Technical Details

what runs on :1904

Fujitsu ICL Terminal Emulator Program C is registered on port :1904 over tcp and udp to Bob Lyon. We don't have a technical write-up for it beyond the IANA registry entry.

In nmap's internet-wide scan data this port is never observed open, so if it's open on your network it's more likely a custom or misconfigured service than the registered one.

find what's listening on :1904

this machine

# linux
sudo ss -tulpn 'sport = :1904'

# macos / bsd
sudo lsof -nP -i :1904

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :1904

another host

nmap -sV -p T:1904 <host>
sudo nmap -sU -sV -p U:1904 <host>

run it? the handshake, the implementations you meet in the wild and the flags that matter come from the engineers who do.

add technical details

Security Information

exposure of :1904

risk score

1/ 10safe

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

remote access averages 3.8 across 213 ports — this one sits 2.8 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

no security notes recorded for :1904 yet

known exploits, hardening advice, what a compromise looks like — suggest an edit if you know its exposure.

Record

iana registry entry

port: :1904
service: Fujitsu ICL Terminal Emulator Program C
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: Remote Access
usage: IANA assigns TCP and UDP port 1904 to the Fujitsu ICL Terminal Emulator Program C. The assignment is registered to Bob Lyon; public scan data has not observed it open.
lookups: 0rank 993
added: 2026-09-19
updated: 2026-09-19
references: IANA service name registry — port 1904

Something wrong?

This record is maintained by the engineers who use port 1904. 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 2026-09-19.

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 213 in remote access →

the 8 most looked-up other ports in remote access — 213 ports carry that label.

port	service	proto	category	risk	views
:8000	Intel Remote Desktop / Alternate HTTP Port	TCP	Web Services	safe	84.3k
:8888	D2GS Admin Console	TCP	Remote Access	caution	83.7k
:8881	Atlasz Secure Server	TCP	Web Services	caution	67.6k
:5938	TeamViewer	TCPUDP	Remote Access	caution	65.0k
:8291	Winbox MikroTik Admin	TCP	Security	caution	62.9k
:8008	IBM HTTP Server Admin	TCP	Web Services	caution	58.3k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:23	Telnet	TCP	Remote Access	caution	34.8k

risk mix of the 8 listed

safe13%
caution88%

0 of 8 encrypted

Port :1904Fujitsu ICL Terminal Emulator Program C

Technical Details

Security Information

Related Ports

Port 1904Fujitsu ICL Terminal Emulator Program C