How to check if webpage is accessed from localhost or from outside?

Question

How can I check from Go whether a webpage is accessed from localhost or from outside? How can I disable some functions for external users? How can I hide the whole site, like "nope, nothing here, port 8080 is closed, move along".

Accepted Answer

To check if website is accessed from outside, check remote IP address. If it is not from 127.0.0.1 or ::1 (IPv6) then it is outside. Use function `func (*IPConn) RemoteAddr`.

To disable some functions check the above condition.

To hide the whole site, bind your service to the localhost interface (127.0.0.1) only.

Binding

```
net.Listen("tcp", "localhost:8080")
```

or

```
net.Listen("tcp6", "ip6-localhost:8080")
```

Using http package

```
http.ListenAndServe("localhost:8080", nil)
```

How to check if webpage is accessed from localhost or from outside?

Solution

Problem