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Port 11321 (arena-server)

IANA assigns port 11321 to arena-server: Arena Server Listen.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
arena-server TCP Arena Server Listen Earl Brannigan -
arena-server UDP Arena Server Listen Earl Brannigan -

Check what is listening on port 11321

Linux: is anything listening on TCP 11321?
sudo ss -tlnp 'sport = :11321'
Linux: UDP 11321
sudo ss -ulnp 'sport = :11321'
Linux / macOS: which process owns the port
sudo lsof -nP -i :11321
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':11321 '
Windows (Command Prompt)
netstat -ano | findstr :11321
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 11321 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 11321
From Windows
Test-NetConnection HOST -Port 11321
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 11321

Block port 11321 in the firewall

ufw
sudo ufw deny 11321/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 11321 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 11321 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 11321' -Direction Inbound -Protocol TCP -LocalPort 11321 -Action Block
ufw
sudo ufw deny 11321/udp
iptables
sudo iptables -A INPUT -p udp --dport 11321 -j DROP
nftables
sudo nft add rule inet filter input udp dport 11321 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 11321' -Direction Inbound -Protocol UDP -LocalPort 11321 -Action Block

Related ports

11319imip11320imip-channels11367atm-uhas11371hkp

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