Port 4443 (HTTPS alternate (4443))

Alternative HTTPS port for appliances, Jitsi Videobridge's TCP fallback and apps that cannot bind 443.

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

What port 4443 is used for

Alternative HTTPS port for appliances, Jitsi Videobridge's TCP fallback and apps that cannot bind 443.

Expose only to trusted sources. Treat like any HTTPS admin interface: patch and restrict.

Service nameProtoDescriptionAssigneeReference

pharos TCP Pharos TeleConsult -

pharos UDP Pharos TeleConsult -

Linux: is anything listening on TCP 4443?

sudo ss -tlnp 'sport = :4443'

Linux / macOS: which process owns the port

sudo lsof -nP -i :4443

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':4443 '

Windows (Command Prompt)

netstat -ano | findstr :4443

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4443 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 4443

From Windows

Test-NetConnection HOST -Port 4443

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 4443 proto tcp

iptables

sudo iptables -A INPUT -p tcp --dport 4443 -s 203.0.113.10 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 4443 -j DROP

nftables

sudo nft add rule inet filter input ip saddr 203.0.113.10 tcp dport 4443 accept
sudo nft add rule inet filter input tcp dport 4443 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'TCP 4443 trusted' -Direction Inbound -Protocol TCP -LocalPort 4443 -RemoteAddress 203.0.113.10 -Action Allow

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