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Port 25004 (icl-twobase5)

IANA assigns port 25004 to icl-twobase5.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
icl-twobase5 TCP icl-twobase5 J A Sever -
icl-twobase5 UDP icl-twobase5 J A Sever -

Check what is listening on port 25004

Linux: is anything listening on TCP 25004?
sudo ss -tlnp 'sport = :25004'
Linux: UDP 25004
sudo ss -ulnp 'sport = :25004'
Linux / macOS: which process owns the port
sudo lsof -nP -i :25004
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':25004 '
Windows (Command Prompt)
netstat -ano | findstr :25004
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 25004 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 25004
From Windows
Test-NetConnection HOST -Port 25004
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 25004

Block port 25004 in the firewall

ufw
sudo ufw deny 25004/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 25004 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 25004 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 25004' -Direction Inbound -Protocol TCP -LocalPort 25004 -Action Block
ufw
sudo ufw deny 25004/udp
iptables
sudo iptables -A INPUT -p udp --dport 25004 -j DROP
nftables
sudo nft add rule inet filter input udp dport 25004 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 25004' -Direction Inbound -Protocol UDP -LocalPort 25004 -Action Block

Related ports

25002icl-twobase325003icl-twobase425005icl-twobase625006icl-twobase7

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