tis 2007-05-29 klockan 21:31 +0200 skrev The Nux: > Hi there, > I am coding a proxy (not something big, I just need it for a project) > in Java, then I would have some questions about proxies : > > * Why does HTTP/FTP/SSL & co proxies exist since SOCKS alone could > do all needed tasks ? Squid is a HTTP proxy. All communication to Squid is HTTP. But HTTP proxies can resolve a number of different URL-schemes for their HTTP clients.. The difference between an HTTP proxy and SOCKS is that the HTTP proxy is fully aware of the protocol being proxied, and as result have well defined behavior. The main difference is the ability to cache results. SOCKS on the other hand is protocol neutral and SHOULD NOT perform caching or other heavily protocol dependent actions. > * Can I force firefox (or anything else) that support both HTTP and > SOCKS to use SOCKS for seeing web pages ? Sure. Just set the SOCKS proxy field in the proxy settings instead of the HTTP proxy, or use a proxy.pac script returning the desired SOCKS proxy details. With the proxy.pac method you can select in detail when to use what kind of proxy.. (HTTP or SOCKS or DIRECT). > * Where can I find specs for doing HTTP/FTP/SSL/Gopher proxy ? HTTP proxies acts as gateways for the other schemes, with the exception of SSL which is tunneled using the CONNECT method. CONNECT is defined in RFC2817. The details regarding ftp and gopher can be found in RFC1738 where the ftp:// and gopher:// URI schemes is defined. The general stuff regarding HTTP proxying is in RFC2616. > * How comes that all proxy services are listening on the same port ? > Does the proxy server bind to specific protocol proxy according to > what headers looks like ? A HTTP proxy only talks HTTP to it's clients regardless of which URI-scheme the client requests. An HTTP proxy request for an HTTP object looks like GET http://server/path HTTP/1.1 Host: server [other headers] And for an FTP object GET ftp://server/path HTTP/1.1. Host: server [other headers] and it's the proxy responsibility to figure out how to get the requested resource and map it to an HTTP response to the client. You are welcome to ask HTTP protocol or code questions on squid-dev@xxxxxxxxxxxxxxx Regards Henrik
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