Snort mailing list archives
Monitoring GigE links without a mirror port
From: "Daniel Wiley" <dwiley () masergy com>
Date: Thu, 28 Mar 2002 10:15:24 -0500
The Problem: Monitoring Full-Duplex Gigabit Ethernet links without spending thousands! After weeks of playing with splitters and switches I was getting disappointed that I couldn't get full-duplex Gigabit Ethernet monitoring without a switch (for aggregation or mirroring) a tap and a snort box. Using basically the same methodology that Check Louie at http://rr.sans.org/intrusion/internal.php used which was working without a hitch but there are three problems. 1. Taking both TX connections and bundling the two TX's on the switch into a single gigabit line could cause large packet loss at anything over 1 gigabit. 2. Switches cost A LOT of $$$$$ especially with multiple Gig ports and mirroring. 3. Multiple fiber taps are also expensive. Port mirroring work's ok if you have a switch that supports it, but it uses a considerable amount of processor, and in my environment the switch in question can't do port mirroring reliably. So I was thinking....To reduce the need for a switch with mirroring and to cut costs why not use two GigE cards. I could use a single GigE tap and try to get snort running in parallel over two cards (not an easy task). So it came to me why not use the bonding feature in Linux... Here is what it looks like |------| TX |------| |ROUTER|--------------|SWITCH| | | Tap | | | |--------------| | |------| RX | -------- | | / \ / \ TX TX -------------- | Linux/Snort| --------------- Each one of the TX lines is terminated into the RX port on a single GigE nic (TX on the Nics are not used). In my case I used an all Intel box with Intel GigE nics. After getting bonding in the kernel and working I put all the nics into the bonded interface and put them all into promisc mode fired up snort on the bonded interface and everything works great. I'm in the process of testing the stability of this setup and if anyone is interested I'll email you the results. So my big question to the list is performance. I know the limitations of snort at this point but I wonder if anyone else has tried anything like I have and what there experience has been. Thanks, Daniel _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
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- Monitoring GigE links without a mirror port Daniel Wiley (Mar 28)