TCP Connection Tester
Test whether a remote TCP host:port accepts connections.
The TCP Connection Tester is an indispensable online utility for anyone needing to verify the accessibility of a specific TCP port on a remote host. Instead of guessing whether a service is down or if a firewall is blocking access, this tool provides a definitive answer by attempting a direct TCP handshake.
Imagine you're a developer deploying a new web application and need to ensure your backend database (e.g., PostgreSQL on port 5432) is reachable from your application server. Or perhaps you're a system administrator troubleshooting why users can't connect to an SSH server (port 22) after a firewall rule change. Our tool helps you instantly confirm if the remote port is open and accepting connections.
Simply input the target hostname or IP address (e.g., example.com or 192.168.1.1) and the specific TCP port number (e.g., 80, 443, 22). The output will clearly indicate whether a connection was successfully established or if it failed, along with a reason like "Connection Refused" or "Timeout." A crucial tip: this tool only tests TCP connectivity; it doesn't validate application-layer protocols or data content. It simply confirms if the "door" is open and someone is "listening." This focus makes it incredibly fast and efficient for basic network diagnostics.
How to use TCP Connection Tester
Enter Target Host
Input the hostname (e.g., www.google.com) or IP address (e.g., 8.8.8.8) of the remote server you wish to test.
Specify Port Number
Enter the specific TCP port number you want to check for connectivity (e.g., 80 for HTTP, 443 for HTTPS, 22 for SSH).
Initiate Test
Click the "Test Connection" button to send a connection request to the specified host and port.
Review Results
Observe the output message, which will indicate "Connection Successful" or provide details about why the connection failed (e.g., "Connection Refused," "Timeout").
Frequently Asked Questions
What does "Connection Refused" mean?
This usually indicates that the host received your connection request but explicitly denied it. This often happens when a service isn't running on that port, or the host's operating system actively rejects connections (e.g., port closed by local firewall).
How is this different from a ping command?
ping checks if an IP address is reachable using ICMP packets, primarily testing basic network connectivity. The TCP Connection Tester specifically attempts to establish a TCP handshake with a port on a host, verifying if a service is actively listening.
Can I test UDP ports with this tool?
No, the TCP Connection Tester is specifically designed for TCP (Transmission Control Protocol) ports. UDP (User Datagram Protocol) connections operate differently and cannot be reliably tested for "listening" status in the same way.
What IP address formats are supported for the host?
You can enter both IPv4 addresses (e.g., 192.168.1.1) and valid domain names (e.g., api.example.com). The tool will resolve the domain name to an IP address before attempting the connection.
What if my connection attempt times out?
A timeout typically means the tool tried to connect to the host and port but didn't receive any response within a reasonable timeframe. This could be due to network latency, an unresponsive host, or a firewall silently dropping packets without sending a "refused" message.
Does this tool work if the remote host is behind a firewall?
Yes, it will attempt to connect. If the firewall is blocking the specified port, the tool will likely report a "Connection Refused" or "Timeout," depending on how the firewall is configured to handle blocked connections. This makes it an excellent tool for troubleshooting firewall rules.