In CGI, the REMOTE_USER environment variable is set with this information. If you are using CGI.pm, you can access this with:

my $query=CGI->new();
my $user=$query->remote_user();
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Otherwise you can do:

my $user=$ENV{'REMOTE_USER'};
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I know no method of retrieving the password (that doesn't mean there isn't one though :) ).

Update: Removed comment that implied retrieving passwords is condonable (sp?). It's not.

CU
Robartes-