Linux Firewalls Post: 7766

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Top Forums UNIX for Advanced & Expert Users Linux Firewalls Post 7766 by loadc on Monday 1st of October 2001 10:54:46 PM

10-01-2001

Registered User

Just a note...

If you have some time, ANtiOnline put out an article the other day,

PIX has an issue with SMTP traffic, it will allow trafiic through and may allow for compromise on mis-configured or older SMTP setups. There is no workaround nor any fix, Cisco is suggesting using another way of securing your smtp server.

Sorry for what seems like a bit of a dig, it's not meant as such,
I agree with the previous poster, if it ain't broke, don;t fix it, but if you really want to change, keep in mind:
Linux ( as of ipchains, not sure with iptables) is a fast firewall, it reads from teh bottom up on the rules file and the first match counts. This makes for fast processing.

BSD, uses berkeley packet filter and reads from the top down with a last match counts ideal. this is slower, but it is much more thorough. that packet will pass through every rule applicable to itself and see what matches and what doesn't. the read is also from the top down, this is a much more understandable format to write rules in (for most, anyway).
It somes to what you want to be saddled with, and which one can you config better/recover faster? Assuming this is your firewall, I am also assuming that you'll want to run SNort or something equally useful inside. A firewall is only a barrier, an IDS is a tool.

Now, if I could go religious on you for a minute...

I've heard from many of the Linux advocates that I work with that "standardizing on one operating system is EXACTLY what is wrong with the Windows approach, that is why they champion Open Source and Linux. Why then, does EVERY ONE of them want EVERYONE to run EVERYTHING on Linux?!?! Isn't that really the same crap in a different pile? I'm not down on Linux, and I don't hate Microsoft, they have done some things I think are fine, but I really think that some of the zealots I work with (I'm not inclusive, I'm only ranting about the ones I know) ought ot take a look at what they are saying and compare it to the Microsoft literature. They might be surprised at how alike they sound in some respects.

I'll get down now,

loadc

loadc

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LEARN ABOUT DEBIAN

apf

APF(1)							      General Commands Manual							    APF(1)

NAME

       apf - easy iptables based firewall system

SYNOPSIS

       apf

DESCRIPTION

       This  manual page documents briefly the apf command.  This manual page was written for the Debian distribution because the original program
       does not have a manual page.

       Advanced Policy Firewall (APF) is an iptables (netfilter) based firewall system designed around the essential  needs  of  today's  Internet
       deployed  servers  and the unique needs of custom deployed Linux installations. The configuration of APF is designed to be very informative
       and present the user with an easy to follow process, from top to bottom of the configuration file. The management of APF  on  a	day-to-day
       basis  is  conducted from the command line with the 'apf' command, which includes detailed usage information and all the features one would
       expect from a current and forward thinking firewall solution.

OPTIONS

       apf follow the usual GNU command line syntax, with long options starting with two dashes (`-').	A summary of options is included below.

       -s|--start
	      load all firewall rules

       -r|--restart
	      stop (flush) & reload firewall rules

       -l|--list
	      list all firewall rules

       -t|--status
	      output firewall status log

       -e|--refresh
	      refresh & resolve dns names in trust rules

       -a <HOST CMT|--allow <HOST COMMENT>
	      add host (IP/FQDN) to allow_hosts.rules and immediately load new rule into firewall

       -d <HOST CMT|--deny <HOST COMMENT>
	      add host (IP/FQDN) to deny_hosts.rules and immediately load new rule into firewall

       -u <HOST>|--remove <HOST>
	      remove host from [glob]*_hosts.rules and immediately remove rule from firewall

       -o|--ovars
	      output all configuration options

COPYRIGHT

       Copyright (C) 1999-2007, R-fx Networks <proj@r-fx.org>
       Copyright (C) 2007, Ryan MacDonald <ryan@r-fx.org> This program may be freely redistributed under the terms of the GNU GPL

       This manual page was written by Giuseppe Iuculano <giuseppe@iuculano.it>, for the Debian project (but may be used by others).

								  August 17, 2008							    APF(1)