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Port 1904 (fjicl-tep-c)

IANA assigns port 1904 to fjicl-tep-c: Fujitsu ICL Terminal Emulator Program C.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
fjicl-tep-c TCP Fujitsu ICL Terminal Emulator Program C Bob Lyon -
fjicl-tep-c UDP Fujitsu ICL Terminal Emulator Program C Bob Lyon -

Check what is listening on port 1904

Linux: is anything listening on TCP 1904?
sudo ss -tlnp 'sport = :1904'
Linux: UDP 1904
sudo ss -ulnp 'sport = :1904'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1904
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1904 '
Windows (Command Prompt)
netstat -ano | findstr :1904
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1904 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1904
From Windows
Test-NetConnection HOST -Port 1904
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1904

Block port 1904 in the firewall

ufw
sudo ufw deny 1904/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1904 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1904 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1904' -Direction Inbound -Protocol TCP -LocalPort 1904 -Action Block
ufw
sudo ufw deny 1904/udp
iptables
sudo iptables -A INPUT -p udp --dport 1904 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1904 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1904' -Direction Inbound -Protocol UDP -LocalPort 1904 -Action Block

Related ports

1902fjicl-tep-b1903linkname1905sugp1906tpmd

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.