Port 8443 (HTTPS alternate)

Alternative HTTPS port used by Tomcat, Kubernetes dashboards, UniFi controllers, Plesk, many appliances' web UIs and some VPN portals.

Registered (user) port, 1024-49151 TCP Web Expose only to trusted sources

What port 8443 is used for

Alternative HTTPS port used by Tomcat, Kubernetes dashboards, UniFi controllers, Plesk, many appliances' web UIs and some VPN portals.

Security: should port 8443 be open?

Expose only to trusted sources. Usually an admin interface. Firewall appliance and VPN portals on 8443 have been a frequent target of mass exploitation; keep them patched and restrict access.

IANA assignment

Service nameProtoDescriptionAssigneeReference

pcsync-https TCP PCsync HTTPS - -

pcsync-https UDP PCsync HTTPS - -

Check what is listening on port 8443

Linux: is anything listening on TCP 8443?

sudo ss -tlnp 'sport = :8443'

Linux / macOS: which process owns the port

sudo lsof -nP -i :8443

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':8443 '

Windows (Command Prompt)

netstat -ano | findstr :8443

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 8443 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine

nc -vz -w 5 HOST 8443

From Windows

Test-NetConnection HOST -Port 8443

Allow only trusted sources on port 8443 in the firewall

Replace 203.0.113.10 with the address or network you trust. With ufw, make sure the default incoming policy is deny.

ufw (one trusted source)

sudo ufw allow from 203.0.113.10 to any port 8443 proto tcp

iptables

sudo iptables -A INPUT -p tcp --dport 8443 -s 203.0.113.10 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 8443 -j DROP

nftables

sudo nft add rule inet filter input ip saddr 203.0.113.10 tcp dport 8443 accept
sudo nft add rule inet filter input tcp dport 8443 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'TCP 8443 trusted' -Direction Inbound -Protocol TCP -LocalPort 8443 -RemoteAddress 203.0.113.10 -Action Allow

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