Hello Mahdi
Yes, but you need an extra plug-in to perform the authentication before it.
Normaly we use SQUID with some kind of auth like NTLM, Kerberos or Basic auth.
You can find lots of documentations searching on google.
Basically your users will connect to SQUID, perform the authentication then Squid will forward the connections to E2Guardian with the authentication (user) information.
I hope that helps you,
Regards
Fabricio.