Port 8443 PCSYNC-HTTPS
Port 8443 is the IANA-assigned pcsync-https port for PCsync HTTPS (TCP / UDP).
What is port 8443 used for?
Port 8443 is assigned to pcsync-https and uses TCP / UDP. The IANA registry describes the service as “PCsync HTTPS”. It sits in the registered range, the block used by databases, application servers and developer tooling. Port conflicts here are common when several local services start at once.
Ports are the transport-layer address a service listens on. A client that wants to reach pcsync-https connects to port 8443. A TCP connection is refused when nothing is listening, while a UDP request simply goes unanswered. That is why a port conflict appears whenever two processes try to bind the same number.
Use the commands below to confirm whether port 8443 is actually in use before you change firewall rules. Blocking the port stops new inbound traffic at the firewall, but it does not stop a local process from listening, and it does not remove the service from the machine.
Source: IANA Service Name and Transport Protocol Port Number Registry.
Check and block port 8443
Copy-ready commands for the protocols assigned to this port. Run the check first, then block only what should not be reachable.
Check on Linux
sudo ss -tlpn 'sport = :8443'
sudo ss -ulpn 'sport = :8443'Check on Windows
Get-NetTCPConnection -LocalPort 8443 -State Listen -ErrorAction SilentlyContinue
Get-NetUDPEndpoint -LocalPort 8443 -ErrorAction SilentlyContinueBlock with UFW
sudo ufw deny 8443/tcp
sudo ufw deny 8443/udpBlock with iptables
sudo iptables -A INPUT -p tcp --dport 8443 -j DROP
sudo iptables -A INPUT -p udp --dport 8443 -j DROPThese commands are examples for a typical host. Check the listener before you change firewall rules, and persist iptables rules with iptables-save or netfilter-persistent. On Windows, use Windows Defender Firewall or New-NetFirewallRule for persistent blocks. The iptables rules here cover IPv4; mirror them with ip6tables if IPv6 is enabled.
Is port 8443 safe to expose?
This alternate HTTPS port often fronts administrative consoles. Confirm the certificate, authentication and access policy before exposing it. Expose this port only when the service is actually needed. Keep it patched, prefer an encrypted alternative, and limit source addresses with a firewall allowlist.
Where port 8443 is usually used
Most traffic on port 8443 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.
- Serving a website, API or reverse-proxy traffic that clients reach on port 8443.
- Load-balancer and uptime checks probing the port before routing requests.
- Local development, where a browser or curl calls the service on localhost:8443.
Inspect the admin TLS endpoint
The TLS handshake reveals the certificate used by the administrative console.
openssl s_client -connect 127.0.0.1:8443Common problems with port 8443
Connection refused or timed out
Refused usually means the host is reachable but nothing is listening on port 8443. A timeout more often means a firewall drop, a wrong host or a service bound to a different interface.
Port already in use
Find the process holding the port with sudo ss -tlpn 'sport = :8443' or sudo lsof -i :8443. Stop that process or configure it to bind another port; killing it without identifying it can take down a production service.
Firewall rule did not survive a reboot
UFW and Windows Firewall keep rules across restarts. Raw iptables rules do not: save them with iptables-save or the netfilter-persistent package, and re-apply after upgrades that reset the ruleset.
The port is blocked but still reachable
A firewall rule filters inbound traffic; it does not close the listener. Confirm with the check command above and bind the service to 127.0.0.1 when only local clients need it.
Port 8443 at a glance
| Port number | 8443 |
|---|---|
| Service name | pcsync-https |
| Transport protocol | TCP / UDP |
| Category | Web and HTTP |
| Range | Registered port (1024–10000) |
| Risk level | Medium |
| Registered assignee | Not listed |
| Registry description | PCsync HTTPS |
| Source | IANA Service Name and Transport Protocol Port Number Registry |
Frequently asked questions
What is port 8443 used for?
Port 8443 (PCSYNC-HTTPS) uses TCP / UDP. PCsync HTTPS.
How do I check if port 8443 is open?
On Linux run `sudo ss -tlpn 'sport = :8443'` and `sudo ss -ulpn 'sport = :8443'`. On Windows run `Get-NetTCPConnection -LocalPort 8443 -State Listen -ErrorAction SilentlyContinue` and `Get-NetUDPEndpoint -LocalPort 8443 -ErrorAction SilentlyContinue` in PowerShell. If the port is open, the output shows a process listening on port 8443; empty output usually means nothing is bound to it.
How do I block port 8443?
With UFW run `sudo ufw deny 8443/tcp` and `sudo ufw deny 8443/udp`. With iptables run `sudo iptables -A INPUT -p tcp --dport 8443 -j DROP` and `sudo iptables -A INPUT -p udp --dport 8443 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot.
Is port 8443 safe to expose?
This alternate HTTPS port often fronts administrative consoles. Confirm the certificate, authentication and access policy before exposing it. Nevertheless, expose this port only when the service is actually needed. Keep it patched, prefer an encrypted alternative, and limit source addresses with a firewall allowlist.
Related ports
- Port 8433 · aws-as2Non Persistent Desktop and Application Streaming
- Port 8445 · copyPort for copy peer sync feature
- Port 8280 · synapse-nhttpSynapse Non Blocking HTTP
- Port 8688 · openremote-ctrlOpenRemote Controller HTTP/REST
- Port 8243 · synapse-nhttpsSynapse Non Blocking HTTPS
- Port 8800 · sunwebadminSun Web Server Admin Service
Primary data: IANA Service Name and Transport Protocol Port Number Registry.
Last reviewed 2026-10-30 · Methodology · About · Privacy