This is an odd problem. The specific code which seems to be failing (returning undef) is this routine in Net::SNMP::Transport::UDP:

sub _socket_create
{
  IO::Socket->new->socket(PF_INET, SOCK_DGRAM, (getprotobyname('udp'))
+[2]);
}
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and _socket_create is called by this fragment in Net::SNMP::Transport:

      if (!defined($this->{_socket} = $this->_socket_create)) {
         $this->_perror('Failed to open %s socket', $this->type);
         return wantarray ? (undef, $this->{_error}) : undef
      }
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If you can verify that this is indeed the case it would really help. I can't think right now of a reason why it should fail unless the user the CGI script is running under is unable to create sockets. Is that a possibility?