sheer <(E-Mail Removed)> ้crivait
news:e2rar3$1t5$(E-Mail Removed):
> BTW, is the way to use proxy servers for other protocols than http in
> general, for instance for mail, nntp etc. (if not, then why among
> thunderbird's preferences options there is one to set a proxy server
> data?)
Proxy HTTP is well known (ex: squid).
Mail server may be used as proxy (that's called a smart mail relay), in
fact a mail relay server is a standard way to configure mail server in
corporate company. And the mail server of your ISP is a mail proxy for
their clients.
The NEWSGROUP network is already working as a "chain of nntp proxy". Your
ISP is hosting a such relay/proxy. You may install your own nntp server
or proxy/relay (ex: INN or nntpcache).
Other protocol/application may have specific proxy.
There is also a "standard" proxy system called SOCKS (v4 or v5), that can
proxy connexion for SOCKS compatible client. In this case the SOCKS proxy
can proxy many protocol (http, nntp, ...), but the client need to include
some code (SOCKS client library).
Note that the connexion tracking system included in the netfilter linux
kernel features, is able to "follow" specific protocol (ftp, rtsp, sip,
....) when they go throw firewall. This is not a real proxy feature but it
adapt the protocol content to adapt the public ip with the private one to
support NAT traversal.
You may use the netfilter feature to do transparent proxy (using a real
proxy server).
Some of these caonnexion tracking mecanisms are included in the
patch_o_mating system (
http://www.netfilter.org).