[ale] ipfwadmin rules?

[Jeremy T. Bouse]

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On Fri, 5 Jun 1998, Nomad the Wanderer wrote:

> Date: Fri, 5 Jun 1998 15:47:58 -0600
> From: Nomad the Wanderer <nomad at orci.com>
> To: Atlanta Linux Enthusiasts <ale at cc.gatech.edu>
> Subject: [ale] ipfwadmin rules?
> 
> Ok
>   If I wanted to block all incoming connections, except ssh and ftp what
> rules would I use?  I read the manpage but for some reason, it's just not
> sinking in...
> 
	Try these rules for ipfwadm right from my /etc/init.d/netbase on
my home computer:

echo "Flush tables..."
ipfwadm -I -f
ipfwadm -O -f

echo -n "Setting incoming filters: "
ipfwadm -I -p deny
# ICMP
echo -n "ICMP "
ipfwadm -I -a deny -b -o -P icmp -S 0.0.0.0/0 -D 0.0.0.0/0

# FTP
echo -n "ftp "
ipfwadm -I -a accept -b -P tcp -S 0.0.0.0/0 -D 0.0.0.0/0 20
ipfwadm -I -a accept -b -P tcp -S 0.0.0.0/0 -D 0.0.0.0/0 21

# SSH
echo -n "ssh "
ipfwadm -I -a accept -b -P tcp -S 0.0.0.0/0 -D 0.0.0.0/0 22

	That should work for you... will only allow FTP and SSH
connections to ports 20-22 while all Outgoing traffic would be able to go
out without a problem... You could expand this to any other service by
duplicating the lines and changing the port number.
	Sincerely,
	Jeremy T. Bouse
	System Administrator

   Jeremy T. Bouse - SouthNet TeleComm Services, Inc - www.STSI.net
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