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Port 4345 (m4-network-as)

IANA assigns port 4345 to m4-network-as: Macro 4 Network AS.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
m4-network-as TCP Macro 4 Network AS Paul Wren -
m4-network-as UDP Macro 4 Network AS Paul Wren -

Check what is listening on port 4345

Linux: is anything listening on TCP 4345?
sudo ss -tlnp 'sport = :4345'
Linux: UDP 4345
sudo ss -ulnp 'sport = :4345'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4345
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4345 '
Windows (Command Prompt)
netstat -ano | findstr :4345
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4345 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4345
From Windows
Test-NetConnection HOST -Port 4345
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4345

Block port 4345 in the firewall

ufw
sudo ufw deny 4345/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4345 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4345 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4345' -Direction Inbound -Protocol TCP -LocalPort 4345 -Action Block
ufw
sudo ufw deny 4345/udp
iptables
sudo iptables -A INPUT -p udp --dport 4345 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4345 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4345' -Direction Inbound -Protocol UDP -LocalPort 4345 -Action Block

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