How to configure drush with Acquia DevDesktop on Windows to access through proxy? There are some answers to similar questions using WAMP, but now drush is not recommended under Windows (unless using DevDesktop, which I am). And this is seriously frustrating. I followed the instructions here and created a wgetrc file with the proxy addresses and use_proxy=on on d:\, then set up a wgetrc environment variable to point to d:\. Stopped and started DevDesktop to verify that the wgetrc variable is taken into account. But when i try to download a module (eg drush dl admin_toolbar), I get an error message:


  simple_xml_loadfile(): I/O warning : failed to load external entity Project.php:74 Failed to get available update data from https://updates.drupal.org/release-history/admin_toolbar/8.x


Following the comments below I tried again (twice). Once, with the env variable WGETRC set to d:\wgetrc, next with the file renamed to _wgetrc as suggested and the env variable set to d:. Neither worked, here is what seems to be the relevant wget output (obtained by redirecting the output to a file):

First attempt:

Wgetrc:
  d:\wgetrc (env)
  /etc/wgetrc (system)
Locale: /usr/share/locale
Compile: gcc -DHAVE_CONFIG_H -DSYSTEM_WGETRC="/etc/wgetrc"
  -DLOCALEDIR="/usr/share/locale" -I. -I/usr/src/wget/wget-1.12/src
  -I../lib -I/usr/src/wget/wget-1.12/lib -D__CYGWIN__ -DEILSEQ=138
  -O3 -fno-unit-at-a-time -s -march=i386 -mtune=i686
Link: gcc -O3 -fno-unit-at-a-time -s -march=i386 -mtune=i686
  -Wl,--enable-auto-import /usr/lib/libssl.dll.a
  /usr/lib/libcrypto.dll.a /usr/lib/libiconv.dll.a
  /usr/lib/libintl.dll.a /usr/lib/libiconv.dll.a -lregex ftp-opie.o
  openssl.o http-ntlm.o gen-md5.o ../lib/libgnu.a


Second attempt:

Wgetrc:
  d:\ (env)
  /etc/wgetrc (system)
Locale: /usr/share/locale
Compile: gcc -DHAVE_CONFIG_H -DSYSTEM_WGETRC="/etc/wgetrc"
  -DLOCALEDIR="/usr/share/locale" -I. -I/usr/src/wget/wget-1.12/src
  -I../lib -I/usr/src/wget/wget-1.12/lib -D__CYGWIN__ -DEILSEQ=138
  -O3 -fno-unit-at-a-time -s -march=i386 -mtune=i686


As far as I can see it is looking in /etc/wgetrc no matter what I do, which is not much use on Windows. In all cases I get this error still:

https://updates.drupal.org/release-history/file_entity/8.x [3.81 sec,16.55 MB]
Executing: wget --version
Executing: wget -q --timeout=30 -O "C:\\Users\\mknapp\\AppData\\Local\\Temp\\dow6C08.tmp" https://updates.drupal.org/release-history/file_entity/8.x
simplexml_load_file(): I/O warning : failed to load external entity    [warning]


I've even tried putting the wgetrc file in c:\windows\system32\drivers\etc but to no avail
You can follow this tutorial to install drush on windows.
http://www.drupal8.ovh/en/tutoriels/95/install-drush-on-widows

For the proxy you can try:

Controle panel -> System -> Advance settings -> variable -> variable system

PROTOCOLE_proxy  NAME:PASSWORD:HOST:IP

http_proxy http://192.168.100.100:3128

https_proxy http://192.168.100.100:3128

Example from : 
http://www.drupal8.ovh/en/tutoriels/208/internet-access-via-proxy