Port Check
Verify if a specific TCP port is open on a target host.
About Port Check
What is a Port Check?
A port check tests whether a specific TCP port on a remote host is open and accepting connections. Ports are numbered endpoints (0-65535) that allow multiple services to run on a single IP address. For example, HTTP uses port 80, HTTPS uses port 443, and SSH uses port 22.
Why We Built This Tool
DevOps engineers frequently need to verify that services are accessible after deployment, firewall rules are correctly configured, load balancers are routing traffic, and security groups in cloud environments are properly set up. This tool provides instant port connectivity checks without needing netcat, telnet, or nmap.
How to Use It
Enter a hostname or IP address and a port number, then click Check. The tool attempts to establish a TCP connection to the specified port and reports whether it is open (accepting connections), closed (actively refusing), or filtered (no response, typically blocked by a firewall). You can check multiple ports in sequence.
Common Ports to Know
Port 22 (SSH), 80 (HTTP), 443 (HTTPS), 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), 27017 (MongoDB), 8080 (HTTP alt), 8443 (HTTPS alt), 3000 (Node.js dev), 5000 (Flask dev), 9090 (Prometheus), 9200 (Elasticsearch), 2379 (etcd), 6443 (Kubernetes API).
Security Implications
Open ports are potential attack vectors. Only expose ports that are necessary for your application. Use firewalls and security groups to restrict access by source IP. Regularly audit open ports with tools like this one. Close unused ports and use non-standard ports for sensitive services like SSH to reduce automated attack surface.