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Old 28th January 2009
jleal jleal is offline
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Default Network Sniffing

I have a FBSD updated box 7.1 stable acting as a gateway of 100 pcs , using ipfw , natd , squid .

Is there any way to detect or prevent network sniffing by the clients?

I have heard about using and IDS , are there other efective tecniques?

thanks in advance!
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Old 1st February 2009
Darwimy Darwimy is offline
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If the client does passive scanning it will be hard to prevent and detect this. But there are some limitations for the clients: If you use a switched network, they will only see traffic going the their own machines. To use a capturing software they usually need to be root / administrator. If you restrict the clients to ordinary users, it will be hard to start the capturing software.

However, if they are able to start software as root / administrator (i.e. by eploiting the local machine, password guessing etc.) they can capture network traffic. This is also true if they can just plug-in their own computer (i.e. a private laptop). They can use a technique called ARP-poisoning then to redirect traffic from other machines to their client.

The latter should be detected by IDS software like snort or others. It may also be able to detect the addition of new hosts to the network.
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Old 4th February 2009
jleal jleal is offline
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Default thanks!

thanks for answering i will try an ids! i ll tell you what happened!
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Old 25th January 2010
SteveJones SteveJones is offline
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Nmap has a script called sniffer-detect that looks for network cards that are in promiscuous mode. I understand there's other ways to sniff traffic without putting your NIC in promiscuous mode but this script might give you a quick idea what's going on.

Last edited by SteveJones; 25th January 2010 at 07:12 PM.
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Old 25th January 2010
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Carpetsmoker Carpetsmoker is offline
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Just FYI, you are replying to a thread that is almost a year old
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Old 25th January 2010
SteveJones SteveJones is offline
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lol

That's ok just thought I would put my .2 cents in

Nice site here by the way.
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