Port Checker Tool by Unboundedata Engineering
Lots of times there is a need in data engineering where one service is setup and it's listening on a port, and one does not know if it's accessible from outside or not. Or it's a handy tool to check if any particular port is not open when it should not be.
Here comes the port checker tool from Unboundedata Engineering to the rescue.!
Lots of times there is a need in data engineering where one service is setup and it's listening on a port, and one does not know if it's accessible from outside or not. Or it's a handy tool to check if any particular port is not open when it should not be.
A successful attempt would look like this:
Try to check on Google DNS public IP address 8.8.8.8 if port 53, which is a port for DNS, is open or not.
An unsuccessful attempt would look like this:
Try to check on Google DNS public IP address 8.8.8.8 if port 1000, which is a fictional port, is open or not. DNS service never listens on port 1000, it should fail.
Troubleshooting:
When the port is open, then it's great, things are hopefully working as expected. However when port is not open, then there are many areas to look to look for during troubleshooting:
Network ACLs/Security Groups Configuration
1. If working in the cloud, then do check that network acls are properly configured or security group configuration allows the ports to be exposed out of the VNet or VPC.
Is service running?
2. At OS level, do check that the intended service itself is running or not. If service is not up, then it won't be listening on the intended port. Say for example a web browser is supposed to listen on port 80, however if the web service is not running then service is not up and won't be listening on port 80.
- If the service is not running then check the error logs for the respective service.
Is service running?
3. If service is running and still not accessible then it's possible then OS firewall may be blocking the incoming traffic to port from external requests.
Popular Ports
These are the popular ports for quick reference.
| Port # | Service |
|---|---|
| 22 | SSH |
| 23 | Telnet |
| 25 | SMTP |
| 53 | DNS |
| 80 | HTTP |
| 88 | Kerberos |
| 115 | SFTP |
| 123 | NTP |
| 389 | LDAP |
| 443 | HTTPS |
| Jacob | Thornton |
| 1433 | MSSQL |
| 2181 | Apache Zookeeper |
| 3306 | MySQL |
| 5432 | PostgresSQL |
| 9092 | Apache Kafka |
Conclusion
Port checker is a simple but handy tool, feel free to try out if your external IPs or FQDNs are listening to the service as expected or not. If they should not be listening or exposed to the public internet, then probably it's a good idea to lock them down.
Next Steps
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info@unboundedata.com
References:
https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers