SPUG: overriding a module's normal behavior

Jon Burdge jlb at io.com
Tue Mar 1 10:25:13 PST 2005

As background, I needed to use Net::SSH::Perl to log into machines in an 
automated fashion, unfortunately some of these machines require 
keyboard-interactive authentication, and it's not easy or desirable to get 
all of the machine's configs updated.  Net::SSH::Perl didn't seem to have 
a way to force keyboard-interactive authentication to use stored 
credentials (which I presume is simply a feature of well-behaved SSH 
clients, but didn't meet my needs.)

I'd rather not have to provide a custom hacked-up version of 
Net::SSH::Perl to run with this script, and it it looked like it would be 
non-trivial to inherit from Net::SSH::Perl and change things that way. 
In fact I would almost guess it was designed to make doing that kind of 
thing difficult.

So, in the interest of just getting things done and not messing with the 
standard libraries, I loaded Net::SSH::Perl::Auth::KeyboardInt, then 
defined *Net::SSH::Perl::Auth::KeyboardInt::authenticate to point to a 
subroutine I provide.

The question, then, is what are the downsides of this approach?  Is this a 
Bad Idea?  I've never really done anything like this in any code other 
than when I've played around to see how it worked.  I did make my code 
check the version of Net::SSH::Perl to provide a warning if the version 
was not the same as the one where I had tested things, but I'm unsure what 
other pitfalls I might need to anticipate.

Any comments? =)


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