Common ports
Every open port is a door. Some should be open to the world, most should not, and a few — databases, remote desktop, file sharing — are how organisations get compromised. This is what listens where.
| Port | Service | Protocol | Should it be public? |
|---|---|---|---|
| 20 | FTP data | TCP | Should not be public |
| 21 | FTP control | TCP | Should not be public |
| 22 | SSH / SFTP | TCP | Safe to expose |
| 23 | Telnet | TCP | Never expose to the internet |
| 25 | SMTP | TCP | Expose with care |
| 53 | DNS | TCP/UDP | Expose with care |
| 80 | HTTP | TCP | Safe to expose |
| 110 | POP3 | TCP | Should not be public |
| 123 | NTP | UDP | Should not be public |
| 143 | IMAP | TCP | Should not be public |
| 161 | SNMP | UDP | Never expose to the internet |
| 389 | LDAP | TCP | Never expose to the internet |
| 443 | HTTPS | TCP | Safe to expose |
| 445 | SMB | TCP | Never expose to the internet |
| 465 | SMTPS | TCP | Expose with care |
| 587 | SMTP submission | TCP | Expose with care |
| 993 | IMAPS | TCP | Expose with care |
| 995 | POP3S | TCP | Expose with care |
| 1433 | Microsoft SQL Server | TCP | Never expose to the internet |
| 1521 | Oracle Database | TCP | Never expose to the internet |
| 2082 | cPanel | TCP | Should not be public |
| 2083 | cPanel (TLS) | TCP | Expose with care |
| 3000 | Node.js / dev server | TCP | Should not be public |
| 3306 | MySQL / MariaDB | TCP | Never expose to the internet |
| 3389 | RDP | TCP | Never expose to the internet |
| 5432 | PostgreSQL | TCP | Never expose to the internet |
| 5900 | VNC | TCP | Never expose to the internet |
| 6379 | Redis | TCP | Never expose to the internet |
| 8080 | HTTP alternate | TCP | Expose with care |
| 8443 | HTTPS alternate | TCP | Expose with care |
| 9200 | Elasticsearch | TCP | Never expose to the internet |
| 27017 | MongoDB | TCP | Never expose to the internet |
Which of these are open on your server?
Scan the common ports from outside your network in about three seconds.