TCP Open Ports Check
Enter a host or IP to check whether common TCP ports are open from the public internet. SysGlass runs a TCP-connect scan across 19 well-known ports (SSH, HTTP/S, mail, databases, RDP, Redis and more) and flags sensitive services that usually shouldn't be exposed. It's a fast external check of a server's attack surface — what the rest of the internet can reach.
Reviewed by the SysGlass team · Updated July 21, 2026
What it checks
- Whether each of 19 common TCP ports accepts a connection (open vs closed/filtered)
- Web (80/443/8080/8443), SSH (22), Telnet (23), DNS (53)
- Mail (25/465/587/993/995/110/143)
- Databases and caches: MySQL (3306), PostgreSQL (5432), Redis (6379)
- Remote access: RDP (3389), FTP (21)
- Highlights sensitive services that are open to the whole internet
How to read the result
- Each open port is listed with the service that usually runs there; closed/filtered ports aren't shown.
- OK with no common ports open, or only expected ones (e.g. 80/443), means the external surface looks tight.
- Warn means a sensitive service is open to the internet — databases (MySQL/PostgreSQL/Redis), RDP or Telnet shouldn't normally be publicly reachable.
- An open port means something accepts connections there; it isn't proof of a vulnerability, but exposed databases and RDP are common breach paths.
- This is a TCP-connect scan of common ports, not a full nmap of all 65535 ports.
Frequently asked questions
What ports does it scan?
19 common TCP ports: FTP, SSH, Telnet, SMTP, DNS, HTTP, POP3, IMAP, HTTPS, SMTPS, Submission, IMAPS, POP3S, MySQL, RDP, PostgreSQL, Redis, and HTTP/HTTPS-alt (8080/8443).
Is it a full open-port check like nmap?
No — it's a fast TCP-connect check of common ports to show a host's typical external surface. For an exhaustive 65535-port or UDP scan, use nmap directly; the tool shows you the equivalent command.
What does 'open' mean?
A TCP connection to that port succeeded, so a service is listening and reachable from the internet. Closed or firewall-filtered ports don't accept the connection and aren't listed.
Why is an open database or RDP port a warning?
Databases (MySQL, PostgreSQL, Redis) and remote-access services (RDP, Telnet) exposed to the whole internet are frequently brute-forced or exploited. They should sit behind a firewall or VPN, or bind to localhost.
Can I scan any host?
Scan hosts you own or are authorized to test. The tool checks common ports from our infrastructure; only run it against systems you're responsible for.