[AusNOG] USB-powered switch +mirror

[Craig Meyers]

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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