The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It allows reliable communication between computers. TCP is the underlying protocol for HTTP / web requests. We use the TCP protocol to check for the state of ports over the internet.
TCP Monitor Specifications:
| Location | Interval | Available States |
|---|---|---|
| los-angeles-us | 5s | No Contact, Open, Closed, Filtered |
| london-uk | 5s | No Contact, Open, Closed, Filtered |
| sydney-au | 5s | No Contact, Open, Closed, Filtered |
| tokyo-jp | 5s | No Contact, Open, Closed, Filtered |
Monitoring an IP address and port with TCP
To monitor an IP address with TCP navigate to the TCP page where you will be able to create one or more checks as needed.
Determining the IP address and Port to monitor
IP Address
If you are unsure what IP address you should be monitoring you can look up the IP address with the following commands:
Linux Hosts:
host $hostname
Example:
host docs.pingsphere.io
docs.pingsphere.io has address 104.28.25.8Windows Hosts:
nslookup $hostname
Example:
nslookup docs.pingsphere.io
Addresses: 104.28.25.8Alternatively, you can use sites like MXToolBox where looking up your domain will return an IP address.
Port
Common ports that people check are:
- 22 (SSH)
- 443 (HTTPS)
- 80 (HTTP)
- 21 (FTP)
- 3389 (RDP)
Otherwise scan through this list of common ports: Wikipedia
Adding the IP address and Port as a TCP monitor
When you have your IP Address and Port you can add the monitor by clicking the Add TCP button in the top right of TCP Monitors.
You're able to add either a single TCP monitor or multiple with a chosen name, which you can use to easily identify this check. Once submitted it will take 5-10 seconds for the new check to be distributed to our edge probes & monitored.
Checking TCP state and editing TCP Monitors
After a little while you will be able to see what the state of your check is. Using the action buttons to the right of your check you can view or delete your monitors.
The above panel shows Port State and Latency
Conclusion
Adding TCP monitors is a great way to get more specific information using pingsphere. Doing so can give you insight into whats available and open to the internet from your service. You might find some ports which are not meant to be accessible.