[Oisf-devel] lua (jit) script keyword

[Victor Julien]

On 09/05/2012 06:07 PM, Peter Manev wrote:
> What is the advantage?
> Besides the fact of course that you can add your own script execution,
> in other words
> what is it that a Lua script gives you that you can not use a rule
> language  for?
> is Lua pattern matching, better and faster than PCRE? - how much
> time/coding would it be needed, if so?

It's a whole scripting language, so there will be much more flexibility
when it comes to detection. We'll have to see how this will perform, so
it's hard to say how useful it will be. But I think for starters we
should threat it like pcre, in other words try to add prefilters like
regular "content" matches.

> 
> 
> 
> 
> On Wed, Sep 5, 2012 at 5:50 PM, Victor Julien <victor at inliniac.net
> <mailto:victor at inliniac.net>> wrote:
> 
>     So Will started bugging me (again) on doing scripting from Suricata and
>     I gave in. Just committed extremely immature, incomplete, experimental
>     luajit scripting support.
> 
>     What it does is that it adds a new keyword, "luajit". There is one
>     argument, a script name. That script is then loaded from your rules
>     directory and ran against a packet. No flow, http or any of that right
>     now, just packets.
> 
>     Example rule:
>     alert tcp any any -> any any (msg:"LUAJIT test"; luajit:test.lua;
>     sid:1;)
> 
>     This loads the script from /etc/suricata/rules/test.lua
> 
>     The script has a "match" function that will return either 1 or 0. 1 for
>     match, 0 for no match.
> 
>     Example script:
> 
>     -- match string HTTP in packet payload
>     function match(args)
>         for k,v in pairs(args) do
>            if tostring(k) == "payload" then
>                 a = tostring(v)
>                 if #a > 0 then
>                     if a:find("HTTP") then
>                         return 1
>                     end
>                 end
>             end
>         end
> 
>         return 0
>     end
> 
>     return 0
>     -- eof
> 
>     The fun thing is that it works, but the best joke is that on my box this
>     simple script makes no performance impact at all.
> 
>     Currently only "payload" and "packet" keys are available. More will
>     follow, or not. This is research stuff, and if we run into some major
>     obstacle we'll remove it or change it completely. Until then, let me
>     know how you feel about it :)
> 
>     Oh yeah, to enable add "--with-
>     libluajit-includes=/usr/include/luajit-2.0/
>     --with-libluajit-libraries=/usr/lib/x86_64-linux-gnu/" to your configure
>     line. Adapt for your distro.
> 
>     Happy scripting!
> 
>     --
>     ---------------------------------------------
>     Victor Julien
>     http://www.inliniac.net/
>     PGP: http://www.inliniac.net/victorjulien.asc
>     ---------------------------------------------
> 
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> 
> 
> 
> 
> -- 
> Regards,
> Peter Manev
> 


-- 
---------------------------------------------
Victor Julien
http://www.inliniac.net/
PGP: http://www.inliniac.net/victorjulien.asc
---------------------------------------------