Re: [exim] ACL filtering 3 dashes in host name

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Szerző: Always Learning
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Címzett: Exim Users
Tárgy: Re: [exim] ACL filtering 3 dashes in host name

Hi Peter,

> > .*-.*-.*-.* : .*adsl.* : .*dynamic.* : .*static.* : .*dial.*


> You could, ...


I shall since it means a problem fixed.

Phil has a very interesting solution

> [0-9]{1,3}[\-\.][0-9]{1,3}[\-\.][0-9]{1,3}.*\.[a-zA-Z]{2,3}$


Returning to your posting .....

> ... but you could also read the doc extract that Mike already
> helpfully pasted for you:


> > http://www.exim.org/exim-html-current/doc/html/spec_html/ch10.html#SECThoslispatnam


I've read that twice before and had a quick glance at it when Mike
posted the link.

> > "If a pattern starts with "*" the remainder of the item must match the
> > end of the host name. For example, *.b.c matches all hosts whose names
> > end in .b.c. This special simple form is provided because this is a very
> > common requirement. Other kinds of wildcarding require the use of a
> > regular expression."


I've read that previously. I could not understand the logic that I can
filter-out *.vn but *-*-*-* would not work. Chris explained it with

"Because it doesn't work that way. Wildcards only work in very specific
circumstances because they are implemented using a performance
optimisation that limits their usefulness."

> PCRE-style regexs and the 'match' operator are what you need here.


I had to do a Google to discover what PCRE is. Its plain old Pearl. My
very large text book on it, purchased circa 1998, remains unread. Its
one more job I have to find time for.

Thanks to everyone for their very helpful comments.

Paul.

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