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Port 3456 (vat)

IANA assigns port 3456 to vat: VAT default data.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
vat TCP VAT default data Van Jacobson -
vat UDP VAT default data Van Jacobson -

Check what is listening on port 3456

Linux: is anything listening on TCP 3456?
sudo ss -tlnp 'sport = :3456'
Linux: UDP 3456
sudo ss -ulnp 'sport = :3456'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3456
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3456 '
Windows (Command Prompt)
netstat -ano | findstr :3456
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3456 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3456
From Windows
Test-NetConnection HOST -Port 3456
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3456

Block port 3456 in the firewall

ufw
sudo ufw deny 3456/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3456 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3456 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3456' -Direction Inbound -Protocol TCP -LocalPort 3456 -Action Block
ufw
sudo ufw deny 3456/udp
iptables
sudo iptables -A INPUT -p udp --dport 3456 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3456 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3456' -Direction Inbound -Protocol UDP -LocalPort 3456 -Action Block

Related ports

3454mira3455prsvp3457vat-control3458d3winosfi

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