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Port 3353 (fatpipe)

IANA assigns port 3353 to fatpipe: FATPIPE.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
fatpipe TCP FATPIPE Sanchaita Datta -
fatpipe UDP FATPIPE Sanchaita Datta -

Check what is listening on port 3353

Linux: is anything listening on TCP 3353?
sudo ss -tlnp 'sport = :3353'
Linux: UDP 3353
sudo ss -ulnp 'sport = :3353'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3353
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3353 '
Windows (Command Prompt)
netstat -ano | findstr :3353
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3353 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3353
From Windows
Test-NetConnection HOST -Port 3353
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3353

Block port 3353 in the firewall

ufw
sudo ufw deny 3353/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3353 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3353 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3353' -Direction Inbound -Protocol TCP -LocalPort 3353 -Action Block
ufw
sudo ufw deny 3353/udp
iptables
sudo iptables -A INPUT -p udp --dport 3353 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3353 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3353' -Direction Inbound -Protocol UDP -LocalPort 3353 -Action Block

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