Snort mailing list archives
Re: Wiring a "read only" cable (Joe Pampel)
From: Wynn Fenwick <wfenwick () entrenet com>
Date: Fri, 30 Nov 2001 22:23:15 -0500
Hi Guys, Correct me if I'm wrong but this works for a hub only and not a switch. Switches would get confused at the logical link layer, would they not, since they would see the same frames on the incoming from the host as were outgoing to the host? I have also tried building the cable that has a schematic listed at http://personal.ie.cuhk.edu.hk/~msng0/sniffing_cable/index.htm While electrically the high-pass filter worked as expected, our Cisco 3500xl compensated for the attentuation, which was obviously off a bit because the R of the cable may not have been accurate enough, or the C value of the cap was not tolerant enough. The host was able to transmit despite the presence of the cap on the Tx wire. W Jay Flowers wrote: No, this is neither a crossover cable, nor are pins 1 and 2 simply cut. (I can easily see how colorblindness would make it difficult or impossible to see that the wire colors of the sniffer cable match the normal one, not the crossover one.) This is a normal ethernet cable, with pins 1 and 2 shorted over to pins 3 and 6 on one side, normal wiring on the other. I suspect this was done by cutting a small amount of insulation off of pins 3 and 6, and soldering in pins 1 and 2, but I'm sure there are other ways to make the splice. This is a pretty cool trick and looks like it will deal with the problem of just cutting the TX wires on 100baseT (which causes the link to go dead and you can't receive). I've not tried it, but it makes some sense to me why this works, and I'll believe Josh that it does work. At 08:23 AM 11/30/2001, Flowers, Jay wrote:
So this is a crossover cable with pins 1 and 2 cut on the crossed side?
Jay Flowers Integic Health Care -----Original Message----- From: Lists [mailto:lists () ironcomet com] Sent: Friday, November 30, 2001 6:19 AM To: Josh Oshiro Cc: snort-users () lists sourceforge net Subject: Re: [Snort-users] Re: Wiring a "read only" cable (Joe Pampel) I use a simple cable on all of my sniffers. I have successfully used
this
cable on Windows 2000 Pro and Server boxes when deploying Snort. Give it a shot. http://www.ironcomet.com/ethernet.shtml
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Current thread:
- Re: Wiring a "read only" cable (Joe Pampel) Donal Graeme (Nov 29)
- Re: Re: Wiring a "read only" cable (Joe Pampel) Chris Schuler (Nov 29)
- Re: Re: Wiring a "read only" cable (Joe Pampel) Josh Oshiro (Nov 30)
- Re: Re: Wiring a "read only" cable (Joe Pampel) Lists (Nov 30)
- Re: Re: Wiring a "read only" cable (Joe Pampel) Josh Oshiro (Nov 30)
- <Possible follow-ups>
- RE: Re: Wiring a "read only" cable (Joe Pampel) Flowers, Jay (Nov 30)
- RE: Re: Wiring a "read only" cable (Joe Pampel) Matt Kettler (Nov 30)
- RE: Re: Wiring a "read only" cable (Joe Pampel) Flowers, Jay (Nov 30)
- Re: Wiring a "read only" cable (Joe Pampel) Wynn Fenwick (Nov 30)
- RE: Re: Wiring a "read only" cable (Joe Pampel) Flowers, Jay (Dec 03)
- Re: Re: Wiring a "read only" cable (Joe Pampel) Chris Schuler (Nov 29)