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From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199804222124.QAA05889@dyson.iquest.net>
Subject: Re: Static vs. dynamic linking (was Re: Using MD5 insted of DES ...)
In-Reply-To: <199804222056.QAA02964@brain.zeus.leitch.com> from "Greg A. Woods" at "Apr 22, 98 04:56:25 pm"
To: woods@zeus.leitch.com
Date: Wed, 22 Apr 1998 16:24:19 -0500 (EST)
Cc: freebsd-security@FreeBSD.ORG
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> [ On Wed, April 22, 1998 at 22:24:24 (+0200), Mark Murray wrote: ]
> > Subject: Re: Static vs. dynamic linking (was Re: Using MD5 insted of DES ...) 
> >
> > Is my summary OK?
> 
> If you're looking for a consensus, then no.   ;-)
> 
> (in certain circumstances I find any dynamic loading of code, be it
> through shared libraries, or run-time loading of .o's, or whatever, to
> be highly undesirable, and I think that's effectively what several other
> people have concluded too)
> 
Dynamic linking of binaries <can> have both negative CPU usage and
memory usage consequences.  Shared libs are not always a win.  They
are especially bad in the case of shells or other programs where there
are numerous instances (both dynamic and static.)

For WWW servers with CGI's they are bad.  For WWW servers with lots
of daemon instances, they are bad for the daemon.  For FTP servers,
the ftpd should not be shared.  For mail hubs, the sendmail should
not be shared.  Basic, simple commands should not be shared, for
recovery reasons.

The only time that they are an almost guaranteed win is when the libaries
are large and complex, like X windows apps.

(I am assuming that disk space isn't much of a concern anymore, due to
 the amazingly low cost of disk space today.)

John

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