Re: regexless parsing, again?

Daniel Cid wrote:
> How do I do with ossec? Well, first, I divide the
> process in two: log decoding and then "classification"
> or rule matching. Second, instead of thousands of
> regexes for every log, I build a decoding/rule tree,
> limiting the number of checks per log.
>   
How does your sshd example differ from a regex like

sshd.*(login failure|access denied|I am a hacker)

I realise that

sshd.*login failure
sshd.*access denied
sshd.*I am a hacker

would be slower - but shouldn't "better written global regex" equate to
your idea of separation? I guess I'm thinking that most modern regex
"engines" will automatically create internal "trees" for well written
regex rules.

-- 
Cheers

Jason Haar
Information Security Manager, Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417
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