>ipfwadm -I -i deny -P tcp -S 24.48.0/0/0/0 0 -D localhost 0 -e -v
>ipfwadm -I -i deny -P udp -S 24.48.0/0/0/0 0 -D localhost 0 -e -v
Your syntax is wrong. Also, understnad that you must NOT filter
out your own IP subnet. Since you are on the 24.x.x.x Class-A,
you are with TCI.net and/or @Home. Do you get a static IP
or an IP via DHCP?
Regardless, if any of the cablemodem's news, mail, etc servers
are in this 24.48.x.x subnet, communications for NNTP, mail,
etc will NOT get to you.
Anyway, try this:
NOTES:
1) Removing the -P tcp and -P udp is fine. Without
specifically mentioning them, TCP, UDP, and
ICMP should be DENIED!
2) I'm assuming that eth0 is the ethernet card to
the cablemodem
3) I always recommend to REJECT traffic. This makes your
machine look as if its not ABLE to do TELNET, FTP, etc.
Ie. try telneting to a windows95/NT machine. Then
try telneting to a Linux box that denies that traffic.
they react different.
--<begin>--
extnic='/sbin/ifconfig | grep -A 4 eth0 | awk '/inet/ { print $2 } ' | sed -e
s/addr://'
ipfwadm -I -i reject -S 24.48.0.0/16 -D $extnic/32 -o
--<end>--
>What would the proper syntax be for ipfwadm for thi? I basically want
>to block everything, so my ISP can see my cable modem, and nothing else
>beyond it. (my cable modem goes to the linux box)
To be honest Phil, you should be a LOT more anal retentive than
this. I personally only allow a FEW IPs into my Cablemodem attached
Linux box for TELNET, FTP, etc. Then, beyond SMTP and DNS, I REJECT
all other traffic. If you would like to see my firewall ruleset,
lemmie know. I've posted about 5 times to the list in the last week
or so.
I will post all these changes to my TrinityOS doc but I've been too
busy.
--David
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