SOLVED: Running MCPAN behind an authenticating proxy server (kludge)

[David Filmer]

I'm behind an HTTP proxy server which requires authentication. I was
having difficulty using -MCPAN to do module installs. The docs contain
some suggestions which did not help in my situation. LWP does not work
(does it EVER work?). So I thought I would share the solution that I
arrived at. It's a KLUDGE, but it works.

None of the supported CPAN communication methods (LWP, ftp, ncftp,
lynx, etc) would work behind my proxy server, regardless of how many
parameters or configuration files or environment variables I fooled
with. I Googled usenet, and found lots of suggestions, but nothing
helped.

But I was able to get it to work using an excellent, open-source
program called cURL. cURL is similar to (but much more powerful than)
wget. cURL is bundled with many Linux distros, or you can get it from
http://curl.haxx.se. I'm using AIX and installed cURL from an IBM RPM
(http://www-1.ibm.com/servers/aix/products/aixos/linux/download.html)

I have NO problems getting cURL to work with my authenticating proxy
server. To simplify the process, I created a cURL resource file,
$HOME/.curlrc (chmod 600) which contains these two parameters:
-x proxy.whatever.com:8080
-U myuserid:mypassword
The "-x" parameter specifies the hostname and port of the proxy
server, the "-U" (uppercase) is my proxy server userID and password.
cURL finds and uses this resource file by default.

But how do I get the CPAN module to use cURL? Simple. I lie to it. In
my CPAN/Config.pm file (in @INC) I edit the value of 'wget' thus:

'wget' => q[/usr/bin/curl],

To prevent the use of other external methods that won't work, I pass
null values to these CPAN/Config.pm keys:

'lynx' => q[],
'ftp' => q[],
'ncftp' => q[],
'ncftpget' => q[],

Don't bother defining anything for the *proxy* keys - leave them null.
cURL will do the proxy negotiation using the $HOME/.curlrc parameters.

Now CPAN thinks that my cURL is my wget program (and it thinks wget -
er, cURL - is the only external method available). But I need to tweak
the CPAN module itself to make this work (and, if you ever update the
CPAN module, you will need to tweak it again). Edit CPAN.pm (in @INC)
and find the bit of code that says:

} elsif ($f eq "wget"){
$src_switch = " -O -";
}

Change the scalar assignment to:

$src_switch = " -- "; #was: $src_switch = " -O -";

It should work now, but you will get warning messages (and delays) as
CPAN tries (and fails) to use the built-in communication methods (LWP
and Net::FTP) first. So you might want to tweak your CPAN.pm module a
little further.

To prevent the CPAN module from trying LWP and Net::FTP first, I also
made a small change to the "has_usable" subroutine. Namely, I added a
preemptive false return, like this:

sub has_usable {
my($self,$mod,$message) = @_;
return $HAS_USABLE->{$mod} = 0; #force it reject LWP and Net::FTP
...

And to avoid seeing pesky (and prolific) LWP warning messages, I
commented out the line that says
#$CPAN::Frontend->myprint("LWP not available\n");

Now I can use -MCPAN to do module installs behind my authenticating
HTTP proxy server. It's quick and clean to use (even if it's a
kludge). Maybe it might help you if you're in a similar environment.

Cheers!