Re: Common issues gathering local interface information...

[bsilva]

Sorry, I should have mentioned that this addresses Chris' question not
Kris'.   ;-)

Brad


-------------------
Good luck or good manuals, which do you want?


On Mon, 22 Sep 2008, bsilva wrote:

>
> While there still are a few tools that want an IP address on an interface,
> most (including tcpdump) are fine without one.
>
> What may be happening is that the interface is down, but the tool you're
> using to assign the interface also brings it up.
>
> try: (substitute your interface for "eth3")
>
> # ifconfig eth3 up
> or
> # ip link set eth3 up
>
> (depending on whether you're used to using "ifconfig" or "ip")
>
>
> Either of these commands will bring the interface up without assigning it
> an IP address.  Tcpdump works fine for me in this fashion.
>
>
>
> Regards,
> Brad
>
>
> -------------------
> Good luck or good manuals, which do you want?
>
>
>
>
> On Mon, 22 Sep 2008, Chris Fowler wrote:
>
> > Kris van Rens wrote:
> > >
> > > However, SIOCGIFCONF does not return interface information of
> > > interfaces that have no IP-address, so this method was rejected due to
> > > the need for this capability.
> > >
> > This might be related to an issue I am having.  I have a box with a 4
> > port RouterBoard.  I'm using all 4 ports in a bridge to sniff parts of the
> > network.  Since the bridge is not part of the network, I do not assign
> > an IP address to it.  Tcpdump complains and some 3rd party sniffing
> > programs
> > refuse to work. The emit an error and terminate.  My fix has been to assign
> > a random IP address not on the host network.
> >
> > Why am I required to assign an address to an interface used only
> > for promiscuous mode?
> >
> > Chris
> >
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> >
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