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Port 2516 (maincontrol)

IANA assigns port 2516 to maincontrol: Main Control.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
maincontrol TCP Main Control Nathan Sadia -
maincontrol UDP Main Control Nathan Sadia -

Check what is listening on port 2516

Linux: is anything listening on TCP 2516?
sudo ss -tlnp 'sport = :2516'
Linux: UDP 2516
sudo ss -ulnp 'sport = :2516'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2516
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2516 '
Windows (Command Prompt)
netstat -ano | findstr :2516
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2516 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2516
From Windows
Test-NetConnection HOST -Port 2516
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2516

Block port 2516 in the firewall

ufw
sudo ufw deny 2516/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2516 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2516 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2516' -Direction Inbound -Protocol TCP -LocalPort 2516 -Action Block
ufw
sudo ufw deny 2516/udp
iptables
sudo iptables -A INPUT -p udp --dport 2516 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2516 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2516' -Direction Inbound -Protocol UDP -LocalPort 2516 -Action Block

Related ports

2514facsys-ntp2515facsys-router2517call-sig-trans2518willy

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