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TCPDUMP: How do I filter an arp message by checking for equality with arp's hexadecimal value of 0806?

I've spent the last hour trying to figure this challenge out.  I know I can filter out by name but would like to also know how to by hexadecimal value.

I have a capture file and would like to filter arp by its hexadecimal value 0806?  Any additional explanation will be appreciated.  Thanks.
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jeffw22
Asked:
jeffw22
1 Solution
 
ranit8Commented:
The pattern to capture specific bytes from a protocol header in tcpdump is
proto [ offset : length ]

You know that the ethernet header has the 2-byte protocol field after the first 12 bytes (destination and source). So match them with
ether[12:2]

Then apply the bitwise or comparison operations you need; in your case the whole field must have a specific value.
ether[12:2]==0x0806

But watch out the presence of LLC when filtering some protocols, in those cases better using the protocol name.
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jeffw22Author Commented:
thanks.
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