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flat assembler > Linux > How to block Layer2 network traffic?

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asmdev



Joined: 21 Dec 2006
Posts: 18
Hello

Its been a while when I visited you guys.

Is there any way to block connections at as soon as Layer2? programming related.
Do I HAVE to study tc (traffic control) INSTEAD ?
I am able to create AF_PACKET+SOCK_RAW sockets but I can only listen... or not?

I require a guaranteed block, unless my program makes decision - traffic goes nowhere.
Post 01 Apr 2018, 20:28
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Melissa



Joined: 12 Apr 2012
Posts: 55
If you want to block connections that means TCP protocol? For same effect simply block remote address via iptables Wink
Post 04 Apr 2018, 16:25
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asmdev



Joined: 21 Dec 2006
Posts: 18
I never wrote a firewall before. Can somebody throw at a few IOCTLs or a set to functions with correct params.
Unfortunately use iptables or install pfsense on separate computer is typical response.
Post 05 Apr 2018, 04:18
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donn



Joined: 05 Mar 2010
Posts: 105
There's this article on "How to create a micro-firewall with kernel modules and packet filtering". There's also this related packet filtering diagram from Wikipedia which can provide a visual.

Hacking iptables is also possible, which may be what Melissa meant.

I only have a 'barely-working' OpenSUSE on Windows 10 from the Windows Store at the moment, so I can't really test anything out, but converting the LinuxJournal C functions to fasm should be possible. If that example still works (a better, newer approach may have replaced this), it could at least provide a quick running example so you can see if that's what you're looking for. May not be low-enough level for you, however..
Post 05 Apr 2018, 15:53
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