Proxy authentication (username and password)

The most common method is a username and password that the program sends along with the request. They are entered in the proxy line or in separate fields of the program.

The second method is access by IP (whitelist): the proxy lets in requests from addresses you have added, without a password. It is convenient for programs that cannot send a username.

If the credentials do not match, an HTTP proxy responds with code 407. What to do about it is explained on the 407 error page.

In Prokso each plan has its own username and password; access by IP allows up to 5 addresses per plan. Code 407 means either wrong login details or that the plan's traffic has run out.

What the Proxy-Authorization header carries

With a password login, an HTTP proxy receives the header Proxy-Authorization: Basic followed by the string "username:password" in Base64. Base64 is an encoding, not encryption: the string dXNlcjpwYXNz turns back into user:pass with a single command. In SOCKS5 the username and password are also sent as plain text, just in a different format.

Some programs first send a request without credentials and repeat it after receiving code 407 from the proxy. For them, a single 407 in the log right before a successful request is normal.

Special characters in the username and password

A Prokso username can contain parameters with the symbols __, ; and ., for example LOGIN__cr.de;city.berlin. In a terminal the semicolon ends the command, so a line without quotes breaks right after the country. Always put it in quotes: curl -x gw.prokso.com:823 -U "LOGIN__cr.de;city.berlin:PASSWORD" https://example.com.

In the form http://username:password@host:port, the symbols @ and : inside a password break the parsing of the line. Replace them with %40 and %3A, or pass the credentials in separate fields of the program. More examples are in the curl guide.

How to find the cause of a failed login

Check the line in the proxy checker: if it works there, the problem is in how the program passes the credentials. Look for a space at the end of a password copied from a spreadsheet and for a username from another plan. If you use the IP whitelist, remember that it must hold your external address, not your address on the local network. If the login stopped working suddenly, without any changes in the settings, check the remaining traffic: a plan with exhausted traffic also answers with code 407.