Port 4326 (geognosis)

IANA assigns port 4326 to geognosis: Cadcorp GeognoSIS.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference

geognosis TCP Cadcorp GeognoSIS Martin Daly -

geognosis UDP Cadcorp GeognoSIS Martin Daly -

Registry dates for this port: registered 2006-11, last modified 2022-08-12.

Linux: is anything listening on TCP 4326?

sudo ss -tlnp 'sport = :4326'

Linux: UDP 4326

sudo ss -ulnp 'sport = :4326'

Linux / macOS: which process owns the port

sudo lsof -nP -i :4326

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':4326 '

Windows (Command Prompt)

netstat -ano | findstr :4326

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4326 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 4326

From Windows

Test-NetConnection HOST -Port 4326

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 4326

ufw

sudo ufw deny 4326/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 4326 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 4326 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 4326' -Direction Inbound -Protocol TCP -LocalPort 4326 -Action Block

ufw

sudo ufw deny 4326/udp

iptables

sudo iptables -A INPUT -p udp --dport 4326 -j DROP

nftables

sudo nft add rule inet filter input udp dport 4326 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 4326' -Direction Inbound -Protocol UDP -LocalPort 4326 -Action Block

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