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Aug. 17, 2018

main | general :: mailbag :: 14

From: Justin M. Date: 27/7/00

Hello, I would first like to say that I thoroughly enjoyed your book.  I read it from front to back (skipping only the OpenBSD sections), and then I read it again, and again...  It's the first instructional computer book that I actually liked reading.  If only O'Reilly books were so fun!

I am a beginning system administrator at the University of Akron, and my
coworker and I are attempting to set up a firewall by ourselves.  I know
a little something about hardware, so I purchased and built a desktop PC
and acquired a copy of RedHat Linux 6.2.  Then, I found your book. 
Before I sat down to set up the firewall (of which I know nothing
about), I read all the way through the book to get some idea of the task
at hand.  Mostly, the book was very helpful, forcing me to think about
issues I wouldn't have otherwise thought about (or even remembered).  We
were able to install the software without too many problems--it only
took three tries.  This is when the problems began.

We went through the setup of the software as described in Chapter 6. 
Then, before setting up the rules (Chapter 7), we decided to test the
network operability of the firewall.  So, we hooked up one computer to
the inside ethernet card, and a second computer to the outside ethernet
card.  Commence the pinging, but to no avail.  None of the computers
could ping the firewall's inside or outside address.  This didn't seem
right.  So, we contacted one of our friends who has set up Linux
firewalls before for some guidance.

He told us a couple of things that we needed to do, but that weren't
mentioned in the book.  Some of these include adding a line to
/etc/lilo.conf and using "make menuconfig" in /usr/src/linux to
configure the kernel for the ethernet card drivers.  I realize these are
not really firewall issues, but network card configuration issues.  So,
we did these, rebuilt the kernel, copied vmlinux and over to
/boot, and rebooted.  Commence the pinging, still to no avail.

At this point, we are starting to poke at things that we don't think
should matter, but might seeing as how we're both unfamiliar with
Linux.  So I guess my question (after all of that), is do you have any
ideas of what could be wrong?  When attempting to ping from the
firewall, an error message is generated:

>From firewall ( Destination Host Unreachable

The only thing we can think of is maybe our gateway, gateway device, or
route options are set up incorrectly.  If you have any insight into this
situation, it would be greatly appreciated.

Also, when do you think the updated Chapter 6 and 7 will be available
for RedHat Linux 6.2?  Is part of it done yet?  If so, can we take a
look at it?  Or are there obvious changes or problems we should know

Finally, I'd like to thank you for your time.  I patiently await your
reply, knowing  (ok, guessing) that you are a busy man.  Thanks again
for your help.


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