TCP Mapping

Because I wanted to learn Linux, I switch from a Windows NT Proxy/Firewall to a Linux based.  Among other things, with WinGate I could do tcp mapping.
From my client I would specify my proxy server with port 2000.  On the proxy it would forward it to my external SQL server on port 1500.  How could I do that on Linux.  I think I need to use portmap, but I don't understand it. I read the docs and didn't understand it.  Could someone tell me step by step what I need to do?  I'm running squid as my proxy on a RedHat 6.1.
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portmap is not related to this.

You need ipchains, and ipmasqadm (aswell as ipportfw and ipautofw)

Squid is only a http / ftp proxy, and not a Socks Proxy.

For basic redirection, redir (available on is pretty slim and "impossible" to configure wrong. also have some good pointers.

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ivanhAuthor Commented:
Good.  Last related question.  After reading the descriptions and some of the docs (keep in mind I have not completely read it yet) does this mean I do not need squid anymore?  
Almost sounds like IP Masquerading should be able to handle what the proxy did, except for caching.  If this is true, then I won't use squid and I'll just switch to this.  YES/NO?
If you do not need caching you can loose squid.

(of cource, squid has better access control, if you need to block access to certain sites etc etc etc etc)
ivanhAuthor Commented:
Thanks.  Coming from an NT world, Linux/Unix definitely requires someone to understand more about what they are doing rather than using a GUI that does it for you.  It's forcing me to understand, which is good.
I still prefer WinNT over linux when it comes to desktops / high end servers, but for the mid-range serving stuff (and networking, linux is a great platform)
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