Network Security – Hub or Switch?



So, for those that have a little bit of knowledge about network hardware, you’ve probably heard this. “You can’t sniff switched networks”…. wrong…. let’s see what this is about. Older networking hardware was dominated by what’s called a hub. This was basically a “dumb” device that when it received data, it would retransmit the data to every machine connected with the expectation that the correct recipient would answer and all others would ignore that data. Of course, this stream of data is possible to watch and easily available software could log all network traffic fairly easily.


So, anything that is unencrypted could be captured and analyzed by any machine hooked up to a hub. But switches were supposedly smarter and some still think that a switch prevents network sniffing. A switch is supposed to know which machines are connected to which ports. So, data destined for machine A ONLY goes to machine A. This knowledge of what machine is where relies upon MAC addressing. So, this is susceptible to a number of attacks.

First, using easily available software, an attacking machine could flood the switch with bogus (false) MAC addresses, at which point the switch will likely give up and fallover to “hub” mode. Also, it’s possible to change the mac address of a network interface. This is another fairly easily available attack. The idea is that you duplicate the MAC address of the “target machine” and then both machines receive the same data from the switch.

There’s yet another approach though that has more interesting possibilities in the area of risk though. That is something called ARP spoofing (or arp poisoning.)

So, in short, switched networks can easily be sniffed.

Related Posts

Blog Traffic Exchange Related Posts
  • Wireless ethernet security Flexbeta has an article giving a good primer on the different approaches to wireless security that are currently available and what seems to be on track for the next generation of wireless networking. One thing that is worth noting, if it's transmitted through the air it can be intercepted. Breaking......
  • SSH, Proxies (Proxy's?), Tor and Web Browsing For quite some time I've been making use of a dd-wrt modified linksys box on my home network as an openvpn endpoint so that when I'm out and about in the world, I connect the vpn, switch firefox to route through a squid proxy server on the home network and......
  • Strange net problems with a Netgear FS608 switch This was weird and now that the switch is replaced I haven't been able to duplicate it, but let me explain. There was a netgear fs608 (8 port unmanaged) switch plugged into a linksys router (model number not noted.) The cable was straight (although the fs608 has support for link......
Blog Traffic Exchange Related Websites
  • Save Money on Cell Phones [/caption]I've written about how to save money on landline phones, but I realized that I didn't cover cell phones. It's time fix that. There are a lot of people spending too much on their phone bill and if these tips help one or two people, it's well worth the effort.......
  • Save Heaps at Home Saving money on energy bills is something that appeals to everybody, young or old, single or married, rich or poor. Whatever your circumstances, you can benefit from the facilities available online to help you find cheaper energy deals. For example, if you compare energy prices at moneysupermarket, you could......
  • U.S. Government Offers Assistance to Lockheed Martin After Security Breach News on Twitter buzzed recently as security professionals and hackers alike shared information pertaining to a network breach of top U.S. weapons manufacturer Lockheed Martin.  Initially it was not immediately clear if any sensitive information was stolen or compromised, but late Saturday evening,Reuters and MSNBC reported “Lockheed Martin Corp., the......
www.pdf24.org    Send article as PDF   

Similar Posts


See what happened this day in history from either BBC Wikipedia
Search:
Keywords:
Amazon Logo

Comments are closed.


Switch to our mobile site