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Port 3261 (winshadow)

IANA assigns port 3261 to winshadow: winShadow.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
winshadow TCP winShadow Colin Barry -
winshadow UDP winShadow Colin Barry -

Check what is listening on port 3261

Linux: is anything listening on TCP 3261?
sudo ss -tlnp 'sport = :3261'
Linux: UDP 3261
sudo ss -ulnp 'sport = :3261'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3261
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3261 '
Windows (Command Prompt)
netstat -ano | findstr :3261
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3261 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3261
From Windows
Test-NetConnection HOST -Port 3261
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3261

Block port 3261 in the firewall

ufw
sudo ufw deny 3261/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3261 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3261 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3261' -Direction Inbound -Protocol TCP -LocalPort 3261 -Action Block
ufw
sudo ufw deny 3261/udp
iptables
sudo iptables -A INPUT -p udp --dport 3261 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3261 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3261' -Direction Inbound -Protocol UDP -LocalPort 3261 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.