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Port 1511 (3l-l1)

IANA assigns port 1511 to 3l-l1.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
3l-l1 TCP 3l-l1 Ian A Young -
3l-l1 UDP 3l-l1 Ian A Young -

Check what is listening on port 1511

Linux: is anything listening on TCP 1511?
sudo ss -tlnp 'sport = :1511'
Linux: UDP 1511
sudo ss -ulnp 'sport = :1511'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1511
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1511 '
Windows (Command Prompt)
netstat -ano | findstr :1511
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1511 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1511
From Windows
Test-NetConnection HOST -Port 1511
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1511

Block port 1511 in the firewall

ufw
sudo ufw deny 1511/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1511 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1511 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1511' -Direction Inbound -Protocol TCP -LocalPort 1511 -Action Block
ufw
sudo ufw deny 1511/udp
iptables
sudo iptables -A INPUT -p udp --dport 1511 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1511 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1511' -Direction Inbound -Protocol UDP -LocalPort 1511 -Action Block

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