Common attacks and weaknesses
- Traffic can be read and modified on the path (credentials, session cookies, injected content).
- Serves as the entry point for SSL stripping when HTTPS is not enforced.
- Same application-level risks as HTTPS.
Port 80: HTTP
Unencrypted web traffic. Today it should only redirect visitors to HTTPS.
80
How HTTP works
WebA browser sends an HTTP request to port 80 and the HTTP server sends the page back. It travels in clear text: anyone on the path can read it, passwords included.
- Transport
- TCP · UDP · SCTP
- Exposure risk
- 4/10 moderate if reachable from the Internet
- Encryption
- Clear textreadable on the network
- IANA status
- Assigned3 registered services
- Range
- Well-known (0-1023)
- Category
- Web
Is port 80 dangerous?
How to secure it
- Redirect every request to HTTPS with a 301 and enable HSTS.
- Never serve login forms or cookies over plain HTTP.
- Mark cookies Secure so they are never sent on port 80.
IANA registry entries for port 80
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| http | 80 | TCP, UDP, SCTP | World Wide Web HTTP | RFC 9110 | 2021-10-01 |
| www | 80 | TCP, UDP | World Wide Web HTTP | RFC 9110 | 2021-10-01 |
| www-http | 80 | TCP, UDP | World Wide Web HTTP | - | - |
// source: IANA service name and port number registry
Which program uses port 80, and is it reachable?
Linux
sudo ss -ltnup 'sport = :80' # process listening on 80
sudo lsof -nP -i :80macOS
sudo lsof -nP -i :80
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 80 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 80 netstat -ano | findstr :80
From another machine
nmap -p 80 -sV <host> sudo nmap -sU -p 80 <host> nc -zv <host> 80
Block it in the firewall
sudo ufw deny 80/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 80" -Direction Inbound -LocalPort 80 -Protocol TCP -Action Block # Windows
What is port 80 used for?
Unencrypted web traffic. Today it should only redirect visitors to HTTPS.
Is port 80 TCP or UDP?
Port 80 is registered for TCP and UDP and SCTP. In practice the service mostly uses TCP.
Is it safe to open port 80?
It is rated 4/10 (moderate) when exposed to the Internet. Traffic can be read and modified on the path (credentials, session cookies, injected content). Redirect every request to HTTPS with a 301 and enable HSTS.
How do I check if port 80 is open?
On Linux run "ss -ltnup 'sport = :80'", on macOS "lsof -nP -i :80", and on Windows "netstat -ano | findstr :80" to see the local process. From another machine, "nmap -p 80 <host>" shows whether it is reachable.
Other web ports
:443 HTTPS tcp · udp · sctp · low risk :8080 HTTP alternate tcp · udp · high risk :8443 HTTPS alternate tcp · udp · moderate risk :3000 Dev servers / Grafana tcp · udp · moderate risk :5000 Flask / Docker registry / UPnP tcp · udp · moderate risk :8000 HTTP alternate (dev) tcp · udp · moderate risk :8888 Jupyter / HTTP alternate tcp · udp · high risk :9443 HTTPS alternate (admin) tcp · udp · moderate risk