Re: [PLUG] firewall

[LeRoy Cressy <leroy@lrcressy.com>]

Michael Whitman wrote:
> 
> If it is linux and a fairly recent distro you may already have IPTABLES
> installed.
> Stuff which will be helpful can be found at
> http://netfilter.samba.org/documentation/index.html#whatis
> 
> At 02:40 PM 3/27/2002 -0500, you wrote:
> >I want firewalling protection on just one machine

For a really quick filter use:

http://netfilter.samba.org/documentation/HOWTO//packet-filtering-HOWTO-5.html

Most people just have a single PPP connection to the Internet, and don't
want anyone coming back into their
network, or the firewall:

    ## Insert connection-tracking modules (not needed if built into
kernel).
    # insmod ip_conntrack
    # insmod ip_conntrack_ftp

    ## Create chain which blocks new connections, except if coming from
inside.
    # iptables -N block
    # iptables -A block -m state --state ESTABLISHED,RELATED -j ACCEPT
    # iptables -A block -m state --state NEW -i ! ppp0 -j ACCEPT
    # iptables -A block -j DROP

    ## Jump to that chain from INPUT and FORWARD chains.
    # iptables -A INPUT -j block
    # iptables -A FORWARD -j block

-- 
Rev. LeRoy D. Cressy   mailto:lcressy@telocity.com   /\_/\
                       http://www.netaxs.com/~ldc   ( o.o )
                       Phone:  215-535-4037          > ^ <

Jesus saith unto him, I am the way, the truth, and the life: 
no man cometh unto the Father, but by me. (John 14:6)

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