Basicly I would say the difference is :
- a statefull multilayer inspection firewall filters the connection but
doesn`t `break` it, it sort of an advanced packet filter like you would see
on a router, but with knowledge of http/... instead of just the ip
packetfiltering ...
- a proxy `breaks` the connection and acts as `a man in the middle`...
The question of when to use what type of firewall isn`t easily answerred,
and depends on each situation.
Personaly i tend to use both of them, do some statefull inspection, and for
specific protocols add a caching proxy.
Just a slight remark , a proxy doesn`t have to be `visible`. Commercial
firewalls such as NAI`s Gauntlet, but also SQUID
offer `transparent proxying`,...
Regards,
David
-----Original Message-----
From: Hiemstra, Brenno [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 08, 2000 9:26 AM
To: '[EMAIL PROTECTED]'; [EMAIL PROTECTED]
Subject: RE: About Proxy and Firewalls.
Frederic,
firewall <<...>>
A firewall is a set of related programs, located at a network gateway
server, that protects the resources of a private network from users from
other networks. (The term also implies the security policy that is used with
the programs.) An enterprise with an intranet that allows its workers access
to the wider Internet installs a firewall to prevent outsiders from
accessing its own private data resources and for controlling what outside
resources its own users have access to.
Basically, a firewall, working closely with a router program, examines each
network packet to determine whether to forward it toward its destination. A
firewall also includes or works with a proxy server that makes network
requests on behalf of workstation users. A firewall is often installed in a
specially designated computer separate from the rest of the network so that
no incoming request can get directly at private network resources.
proxy server <<...>>
In an enterprise that uses the Internet, a proxy server is a server that
acts as an intermediary between a workstation user and the Internet so that
the enterprise can ensure security, administrative control, and caching
service. A proxy server is associated with or part of a gateway server that
separates the enterprise network from the outside network and a firewall
server that protects the enterprise network from outside intrusion.
A proxy server receives a request for an Internet service (such as a Web
page request) from a user. If it passes filtering requirements, the proxy
server, assuming it is also a cache server , looks in its local cache of
previously downloaded Web pages. If it finds the page, it returns it to the
user without needing to forward the request to the Internet. If the page is
not in the cache, the proxy server, acting as a client on behalf of the
user, uses one of its own IP addresses to request the page from the server
out on the Internet. When the page is returned, the proxy server relates it
to the original request and forwards it on to the user.
To the user, the proxy server is invisible; all Internet requests and
returned responses appear to be directly with the addressed Internet server.
(The proxy is not quite invisible; its IP address has to be specified as a
configuration option to the browser or other protocol program.)
An advantage of a proxy server is that its cache can serve all users. If one
or more Internet sites are frequently requested, these are likely to be in
the proxy's cache, which will improve user response time. In fact, there are
special servers called cache servers. A proxy can also do logging.
The functions of proxy, firewall, and caching can be in separate server
programs or combined in a single package. Different server programs can be
in different computers. For example, a proxy server may in the same machine
with a firewall server or it may be on a separate server and forward
requests through the firewall.
I got this information of www.whatis.com. I thought it was the fastest way
to get a good description of what a proxy server and firewall is. (and saves
a lot of typing work :o))))))
Hopefully a bit informational to you all, especially Frederic,
Greets,
/B
> -----Original Message-----
> From: fr�d�ric smolis [SMTP:[EMAIL PROTECTED]]
> Sent: woensdag 8 november 2000 8:56
> To: [EMAIL PROTECTED]
> Subject: About Proxy and Firewalls.
>
> Hello.
>
> I have difficulties to understand the differences between a firewall and
> a proxy in a security policy within a firm. I think they are both state
> -full inspection. So, why use one rather the other? And I don't talk
> about financial account.
>
> If you have a web site which explain it, thanks to give me this.
>
> Excuse me for my english but I'm french !!
> -
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