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Port 25001 (icl-twobase2)

IANA assigns port 25001 to icl-twobase2.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
icl-twobase2 TCP icl-twobase2 J A Sever -
icl-twobase2 UDP icl-twobase2 J A Sever -

Check what is listening on port 25001

Linux: is anything listening on TCP 25001?
sudo ss -tlnp 'sport = :25001'
Linux: UDP 25001
sudo ss -ulnp 'sport = :25001'
Linux / macOS: which process owns the port
sudo lsof -nP -i :25001
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':25001 '
Windows (Command Prompt)
netstat -ano | findstr :25001
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 25001 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 25001
From Windows
Test-NetConnection HOST -Port 25001
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 25001

Block port 25001 in the firewall

ufw
sudo ufw deny 25001/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 25001 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 25001 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 25001' -Direction Inbound -Protocol TCP -LocalPort 25001 -Action Block
ufw
sudo ufw deny 25001/udp
iptables
sudo iptables -A INPUT -p udp --dport 25001 -j DROP
nftables
sudo nft add rule inet filter input udp dport 25001 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 25001' -Direction Inbound -Protocol UDP -LocalPort 25001 -Action Block

Related ports

24922find25000icl-twobase125002icl-twobase325003icl-twobase4

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