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Ethereal-users: Re: [Ethereal-users] ip broadcast filter

Note: This archive is from the project's previous web site, ethereal.com. This list is no longer active.

From: Guy Harris <guy@xxxxxxxxxx>
Date: Mon, 15 Oct 2001 12:56:57 -0700 (PDT)
> tethereal man page says that capture filters syntax is taken from tcpdump.
> tcpdump man page says:
>     ip broadcast 
> 	True if the packet is an IP broadcast packet. It checks for both the 
> 	all-zeroes and all-ones broadcast conventions, and looks up the local 
> 	subnet mask. 
> 
> The "lookup" part does not seem to work. 
> Tethereal does not recognize these broadcasts.

Does tcpdump recognize them?

If not, this is a libpcap issue.

> My network is 10.0.0.0.
> Can this be the reason ?

Can the fact that your network is 10.0.0.0, in and of itself, be the
reason?  Probably not.

What's the netmask of the interface on which you're capturing?

Does that interface have more than one IP address?  If so, do all of the
IP addresses have the same netmask?  (No, that's not a requirement; my
FreeBSD machine at home has one Ethernet interface, with two IP
addresses with two different netmasks - one is the address/netmask for
my ADSL ISP, and one is an address/netmask for a private network that my
ADSL modem's administration functions are on.)

What are the IP addresses of the broadcast packets that aren't passing
the filter?