TCP Port Monitoring
Visibility into every service, not just your website
TCP port monitoring checks that specific ports are open and accepting connections — covering mail servers, databases, FTP, SSH, and custom application ports that HTTP monitoring never sees.
Any port, any protocol
Monitor SMTP (25/587), IMAP (993), MySQL (3306), PostgreSQL (5432), Redis (6379), RDP (3389), SSH (22), and any custom port.
Connection success verification
Confirm the port accepts a TCP connection — the most reliable indicator that a service is running and accessible.
Fast failure detection
TCP checks fail immediately when a port is closed, without waiting for HTTP application-layer timeouts.
Complements HTTP checks
Combine TCP and HTTP checks on the same host to isolate failures at the network vs application layer.
What TCP monitoring checks
A TCP check attempts to open a TCP connection to a specific host and port. If the connection is accepted, the check passes. If the connection is refused or times out, the check fails. TCP checks do not interpret any application protocol — they operate at the transport layer, below HTTP, SMTP, FTP, or any other protocol.
Services that need TCP monitoring
Mail servers (SMTP, IMAP, POP3) require TCP monitoring because HTTP checks cannot test mail delivery. Database servers that should be accessible from specific application servers need TCP monitoring to verify the port is open and the firewall rules are correct. FTP and SFTP servers, SSH access points, RDP, and custom application ports all require TCP-level monitoring.
Combining TCP and HTTP for complete coverage
For web services, run both checks. If TCP fails and HTTP also fails, your server or network is down. If TCP passes but HTTP fails, your web server or application is broken but the server itself is reachable. This distinction tells you immediately whether the problem requires a server reboot (TCP failure) or an application restart (HTTP failure with TCP passing).
Try TCP Port Monitoring now — free
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