Port Number Lookup
Common port reference with exposure risk warnings
What is Port Number Lookup?
This port lookup table covers the default ports and protocols for more than 40 common services and flags the high-risk ones, such as Redis, the Docker API, and Memcached, where exposing the port to the public internet effectively hands over the host. The data ships with the page, so every lookup runs locally.
How to use Port Number Lookup
- 1Search by port number or service name.
- 2Review the protocol and what the port is used for.
- 3Pay attention to the highlighted exposure warnings.
Frequently asked questions
Which ports should never be exposed to the internet?+
The three most dangerous are 6379 (Redis, which ships with no password by default), 2375 (the plaintext Docker API, equivalent to handing out root), and 11211 (Memcached, which has been abused for record-breaking UDP amplification attacks). Database ports such as 3306, 5432, 27017, and 9200 should likewise be reachable only from a private network or through a bastion host.
Does moving SSH off port 22 actually improve security?+
It cuts a lot of log noise from automated scanners, but it is not a security boundary, since a determined attacker will scan the full port range anyway. What actually helps is disabling password authentication, allowing keys only, running something like fail2ban, and restricting which source addresses can reach the port at all.
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