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Port 12001 (entextnetwk)

IANA assigns port 12001 to entextnetwk: IBM Enterprise Extender SNA COS Network Priority.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
entextnetwk TCP IBM Enterprise Extender SNA COS Network Priority Eugene Cox -
entextnetwk UDP IBM Enterprise Extender SNA COS Network Priority Eugene Cox -

Check what is listening on port 12001

Linux: is anything listening on TCP 12001?
sudo ss -tlnp 'sport = :12001'
Linux: UDP 12001
sudo ss -ulnp 'sport = :12001'
Linux / macOS: which process owns the port
sudo lsof -nP -i :12001
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':12001 '
Windows (Command Prompt)
netstat -ano | findstr :12001
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 12001 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 12001
From Windows
Test-NetConnection HOST -Port 12001
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 12001

Block port 12001 in the firewall

ufw
sudo ufw deny 12001/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 12001 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 12001 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 12001' -Direction Inbound -Protocol TCP -LocalPort 12001 -Action Block
ufw
sudo ufw deny 12001/udp
iptables
sudo iptables -A INPUT -p udp --dport 12001 -j DROP
nftables
sudo nft add rule inet filter input udp dport 12001 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 12001' -Direction Inbound -Protocol UDP -LocalPort 12001 -Action Block

Related ports

11999wmereporting12000entextxid12002entexthigh12003entextmed

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