dump_server_ssl_cert.rb

require 'socket' 
require 'openssl' 
# port can be anything. here it's ldaps
socket = TCPSocket.new("some.secure.server.com", 636) 
ssl_context = OpenSSL::SSL::SSLContext.new() 
unless ssl_context.verify_mode 
  warn "warning: peer certificate won't be verified this session." 
  ssl_context.verify_mode = OpenSSL::SSL::VERIFY_NONE 
end 
sslsocket = OpenSSL::SSL::SSLSocket.new(socket, ssl_context) 
sslsocket.sync_close = true 
sslsocket.connect
# Dump the server's cert to the desktop so I can install it
File.open("/Users/user/Desktop/cert.der", "w+") do |f|
  f.write sslsocket.peer_cert.to_der
end