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Port 20002 (commtact-http)

IANA assigns port 20002 to commtact-http: Commtact HTTP.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
commtact-http TCP Commtact HTTP Tomas Svoboda -
commtact-http UDP Commtact HTTP Tomas Svoboda -

Registry dates for this port: registered 2004-12.

Check what is listening on port 20002

Linux: is anything listening on TCP 20002?
sudo ss -tlnp 'sport = :20002'
Linux: UDP 20002
sudo ss -ulnp 'sport = :20002'
Linux / macOS: which process owns the port
sudo lsof -nP -i :20002
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':20002 '
Windows (Command Prompt)
netstat -ano | findstr :20002
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 20002 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 20002
From Windows
Test-NetConnection HOST -Port 20002
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 20002

Block port 20002 in the firewall

ufw
sudo ufw deny 20002/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 20002 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 20002 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 20002' -Direction Inbound -Protocol TCP -LocalPort 20002 -Action Block
ufw
sudo ufw deny 20002/udp
iptables
sudo iptables -A INPUT -p udp --dport 20002 -j DROP
nftables
sudo nft add rule inet filter input udp dport 20002 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 20002' -Direction Inbound -Protocol UDP -LocalPort 20002 -Action Block

Related ports

20000DNP320001microsan20003commtact-https20005openwebnet

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