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Port 3136 (grubd)

IANA assigns port 3136 to grubd: Grub Server Port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
grubd TCP Grub Server Port Kord Campbell -
grubd UDP Grub Server Port Kord Campbell -

Check what is listening on port 3136

Linux: is anything listening on TCP 3136?
sudo ss -tlnp 'sport = :3136'
Linux: UDP 3136
sudo ss -ulnp 'sport = :3136'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3136
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3136 '
Windows (Command Prompt)
netstat -ano | findstr :3136
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3136 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3136
From Windows
Test-NetConnection HOST -Port 3136
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3136

Block port 3136 in the firewall

ufw
sudo ufw deny 3136/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3136 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3136 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3136' -Direction Inbound -Protocol TCP -LocalPort 3136 -Action Block
ufw
sudo ufw deny 3136/udp
iptables
sudo iptables -A INPUT -p udp --dport 3136 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3136 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3136' -Direction Inbound -Protocol UDP -LocalPort 3136 -Action Block

Related ports

3134ecp3135peerbook-port3137rtnt-13138rtnt-2

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