[AusNOG] USB-powered switch +mirror

[Ben Buxton]

If you want to go the truly hackish route, you could simply build a
passive tap that taps off the two lines into the RX ports of a pair of
ethernet cards.

That's how fibre taps work, it should work on cat5 too.

BB

Craig Meyers <Craig.Meyers at citec.com.au> uttered the following thing:
> 
> Wanted to say thanks for all the ideas guys. On and off-list.
> 
> The request is manly for those situations where the client doesn't have
> a managed switch to mirror the port.
> 
> Hubs are probably a bad idea for what I had in mind. As Sean said below
> - it changes the nature of the connection and could introduce more
> errors than the ones I want to detect.
> 
> Network taps were suggested. These look a great idea. But price for me
> is a bit out of range. Prices I saw in Aus were hovering around the $700
> mark. I guess more suited to permanent monitoring setups.
> 
> A portable 10/100 TAP I saw a price for was $129US:
> http://www.barracudatap.com/
> 
> Love reading all the hacks to savage more power out of a laptop. Also
> you get more power from the PS2 port if you're desperate :)
> 
> The cheapest hack though, is to grab a USB gig ethernet adapter ~$50AUS
> and ethernet cross-over cable, and bridge two ethernet interfaces under
> Windows XP. Then under wireshark select the bridge interface as the
> source for the capture. Works really well.
> 
> -- Craig Meyers
> 
> -----Original Message-----
> From: Sean K. Finn [mailto:Sean.Finn at ozservers.com.au] 
> Sent: Wednesday, 7 January 2009 12:06 PM
> To: Craig Meyers; 'ausnog at ausnog.net'
> Subject: RE: [AusNOG] USB-powered switch +mirror
> 
> 
> The trouble with a Hub would be that it will set the connection to
> half-duplex.
> 
> If Craig is trying to be sneaky and sniff traffic on the wire, then
> changing the duplex may not be an option.
> 
> The Linksys WRT 54GL's offer Vlanning and port mirroring with the DD-WRT
> firmware flash, and are quite handly little boxes.
> 
> According to 
> http://www.wirelessforums.org/alt-internet-wireless/dead-wrt54gl-router-
> 42654.html
> 
> the DDWRT will run on anything from 4V to 18V DC, but at 5V I'd
> definitely turn off the wireless and any extra functionality so as to
> use the bare minimum amount of power.
> 
> I'll give it a try tomorrow with a chopped up USB cable and see if I can
> get lights :)
> 
> -Sean.
> 
> -----Original Message-----
> From: ausnog-bounces at lists.ausnog.net
> [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Craig Askings
> Sent: Wednesday, 7 January 2009 11:55 AM
> To: ausnog at ausnog.net
> Subject: Re: [AusNOG] USB-powered switch +mirror
> 
> The closest thing I can recall to an unpowered hub that was the old thin
> net and thick net coax stuff. T-pieces and Terminators and Vampire Taps!
> Oh my!
>         
> Craig.
> 
> On Wed, 2009-01-07 at 10:53 +1000, Brent Paddon wrote:
> > Unpowered hub? - were there such things?
> > 
> > I have a handful of old hubs around here which are perfect for 
> > mirroring
> > on low speed links.
> > 
> > Brent
> 
> 
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-- 
Ben Buxton - Random Network Person