HTTPfy

Port 4109 (izm)

IANA assigns port 4109 to izm: Instantiated Zero-control Messaging.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
izm TCP Instantiated Zero-control Messaging David Miller -
izm UDP Instantiated Zero-control Messaging David Miller -

Registry dates for this port: registered 2007-02.

Check what is listening on port 4109

Linux: is anything listening on TCP 4109?
sudo ss -tlnp 'sport = :4109'
Linux: UDP 4109
sudo ss -ulnp 'sport = :4109'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4109
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4109 '
Windows (Command Prompt)
netstat -ano | findstr :4109
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4109 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4109
From Windows
Test-NetConnection HOST -Port 4109
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4109

Block port 4109 in the firewall

ufw
sudo ufw deny 4109/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4109 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4109 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4109' -Direction Inbound -Protocol TCP -LocalPort 4109 -Action Block
ufw
sudo ufw deny 4109/udp
iptables
sudo iptables -A INPUT -p udp --dport 4109 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4109 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4109' -Direction Inbound -Protocol UDP -LocalPort 4109 -Action Block

Related ports

4107j-ac4108accel4110g2tag4111xgrid

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