[Snort-users] $HOME_NET question

Matt Kettler mkettler at ...4108...
Wed Jan 22 12:52:07 EST 2003


As per the comments in snort.conf, if you use $eth0_ADDRESS it uses the IP 
*and* netmask of eth0.

# or use global variable $<interfacename>_ADDRESS
# which will be always initialized to IP address and
# netmask of the network interface which you run
# snort at.
#
# var HOME_NET $eth0_ADDRESS

This in your case your home_net is likely going to be 192.168.1.2/24 which 
means that 192.168.1.* will be recognized as part of it.

At 12:13 PM 1/22/2003 -0800, Ralph Churchill wrote:
>I have snort 1.8.7. I have set my $HOME_NET to be
>$eth0_ADDRESS and my external net set to !$HOME_NET.
>However, I still get alerts from other computers on my
>subnet! For example, the "SNMP public access udp" rule
>says:
>
>alert udp $EXTERNAL_NET any -> $HOME_NET 161...
>
>For this example, assume my IP is 192.168.1.2. I'm
>getting  alerts for a packet from 172.20.39.32 to
>192.168.1.3. Why?   I'm totally confused. I thought
>$HOME, if set to $eth0_ADDRESS would only give alerts
>for things coming into my IP?!?! Am I wrong?
>
>RMC





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