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Port 4022 (dnox)

IANA assigns port 4022 to dnox: DNOX.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
dnox TCP DNOX Leo Rathnayake -
dnox UDP DNOX Leo Rathnayake -

Check what is listening on port 4022

Linux: is anything listening on TCP 4022?
sudo ss -tlnp 'sport = :4022'
Linux: UDP 4022
sudo ss -ulnp 'sport = :4022'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4022
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4022 '
Windows (Command Prompt)
netstat -ano | findstr :4022
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4022 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4022
From Windows
Test-NetConnection HOST -Port 4022
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4022

Block port 4022 in the firewall

ufw
sudo ufw deny 4022/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4022 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4022 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4022' -Direction Inbound -Protocol TCP -LocalPort 4022 -Action Block
ufw
sudo ufw deny 4022/udp
iptables
sudo iptables -A INPUT -p udp --dport 4022 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4022 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4022' -Direction Inbound -Protocol UDP -LocalPort 4022 -Action Block

Related ports

4020trap4021nexus-portal4023esnm-zoning4024tnp1-port

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