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Port 3137 (rtnt-1)

IANA assigns port 3137 to rtnt-1: rtnt-1 data packets.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
rtnt-1 TCP rtnt-1 data packets - -
rtnt-1 UDP rtnt-1 data packets - -

Check what is listening on port 3137

Linux: is anything listening on TCP 3137?
sudo ss -tlnp 'sport = :3137'
Linux: UDP 3137
sudo ss -ulnp 'sport = :3137'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3137
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3137 '
Windows (Command Prompt)
netstat -ano | findstr :3137
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3137 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3137
From Windows
Test-NetConnection HOST -Port 3137
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3137

Block port 3137 in the firewall

ufw
sudo ufw deny 3137/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3137 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3137 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3137' -Direction Inbound -Protocol TCP -LocalPort 3137 -Action Block
ufw
sudo ufw deny 3137/udp
iptables
sudo iptables -A INPUT -p udp --dport 3137 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3137 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3137' -Direction Inbound -Protocol UDP -LocalPort 3137 -Action Block

Related ports

3135peerbook-port3136grubd3138rtnt-23139incognitorv

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