Exclude public traffic

asked 2021-12-30 07:10:11 +0000

What filters could i use to remove all the internet chatter in the LAN. Am trying to get a look into all the LAN traffic without applying to broad of filters and accidentally obscuring something regarding multicasting, mDNS, and etc.

Tried basic attempts and inverses of examples but would end up missing things. For example: ip.src in {192.168.0.0/16 172.16.0.0/12 10.0.0.0/8} or ip.dst in {192.168.0.0/16 172.16.0.0/12 10.0.0.0/8} occasional public ip's scattered about. Also since public traffic requires more layers maybe it would be better and easier to specifically exclude it rather than try to pick everything in a lan?

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I think it would be easier to exclude what you don't want. An example to exclude multicast traffic, you can use the filter eth.dst.ig==1.

BigFatCat ( 2021-12-30 19:33:36 +0000 )edit

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answered 2021-12-30 20:01:35 +0000

Jaap

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Extending on your work this comes to the following expression:

ip.src in {192.168.0.0/16, 172.16.0.0/12, 10.0.0.0/8, 169.254.0.0/16, 0.0.0.0} and ip.dst in {192.168.0.0/16, 172.16.0.0/12, 10.0.0.0/8, 224.0.0.0/4, 169.254.0.0/16, 255.255.255.255}

Both source _and_ destination addresses need to be in specific ranges. Otherwise local generated traffic for external addressed would show up.
The source could also be an Automatic IPv4 address (169.254.0.0/8)
The source could also be an unconfigured IPv4 address (0.0.0.0)
The destination could also be a multicast address (224.0.0.0/4)
The destination could also be an Automatic IPv4 address (169.254.0.0/8)
The destination could also be the broadcast address (255.255.255.255)

btw: items in a list should be separated by ,

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Have the extra elements for IPv6 been left as an exercise for the reader :-)

grahamb ( 2021-12-30 20:24:34 +0000 )edit

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