In my Nagios testing I was trying to work with the CHECK_ESX3.PL script to run some scripts against the ESX hosts in the environment. I installed the required VMware vSphere Perl SDK (latest from VMware's site). I was able to run "./check_esx3.pl" without any errors. However when I tried to run an actual check against a host I received:

CHECK_ESX3.PL CRITICAL - Server version unavailable at 'https://172.16.0.81:443/sdk/vimService.wsdl' at /usr/lib/perl5/5.8.8/VMware/VICommon.pm line 545.


I ran across the threads about how the the latest LWP does not like the self-signed certificates. So I added this line to the top of the perl script:
$ENV{PERL_LWP_SSL_VERIFY_HOSTNAME} = 0;

However that did not seem to correct the issue (but it turned out it was one of several issues). I noticed when I rebuilt the VMware vSphere Perl SDK I saw this error:

The following Perl modules were found on the system but may be too old to work
with vSphere CLI:

Compress::Zlib 2.005 or newer
HTML::Parser 3.60 or newer
URI 1.37 or newer
XML::SAX 0.16 or newer

I updated those perl modules as well without seeing a difference. What I eventually did was manually edit the VICommon.pm module. I looked at line 545 which tries to parse the response data. So I added a line to just print out the data prior to that step. That's when I saw the message about a proxy error. Turns out I had http_proxy, ftp_proxy, and https_proxy environment variables set from another idea I had been toying with. I removed the environment variables and I was off and running! So I actually had two issues, the self-signed certificates and the bad proxy environment variables.