diff --git a/dev-install.sh b/dev-install.sh
index 9dc0de2..a925843 100755
--- a/dev-install.sh
+++ b/dev-install.sh
@@ -3,20 +3,28 @@
 set -e
 
 vagrant up
-host=$(vagrant ssh-config | awk '{ if ($1 == "HostName") { print($2) }}')
-port=$(vagrant ssh-config | awk '{ if ($1 == "Port") { print($2) }}')
-key=$(vagrant ssh-config | awk '{ if ($1 == "IdentityFile") { print($2) }}')
+
+if [ -z "$http_proxy" ]; then
+  http_proxy=$(vagrant ssh -- sh -c '. /etc/profile.d/http_proxy.sh 2>/dev/null; echo $http_proxy')
+fi
+
+if [ -z "$http_proxy" ]; then
+  printf "HTTP Proxy[none]: "
+  read http_proxy
+fi
 
 if [ -n "$http_proxy" ]; then
-  proxy="\"command_prefixes\": [\"http_proxy='$http_proxy'\"],"
-else
-  proxy=
+  vagrant ssh -- sudo /vagrant/proxy.sh $http_proxy
+  export http_proxy
 fi
 
+host=$(vagrant ssh-config | awk '{ if ($1 == "HostName") { print($2) }}')
+port=$(vagrant ssh-config | awk '{ if ($1 == "Port") { print($2) }}')
+key=$(vagrant ssh-config | awk '{ if ($1 == "IdentityFile") { print($2) }}')
+
 cat > colab/environments.json <<EOF
 {
   "dev": {
-    $proxy
     "hosts": ["$host"],
     "key_filename": "$key",
     "port": "$port",
diff --git a/proxy.sh b/proxy.sh
new file mode 100755
index 0000000..d582fb4
--- /dev/null
+++ b/proxy.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+set -e
+
+if [ -n "$1" ]; then
+  http_proxy="$1"
+fi
+
+if [ -z "$http_proxy" ]; then
+  echo "No http_proxy in command line or environment!"
+  echo
+  echo "usage: $0 [HTTP_PROXY]"
+  exit 1
+fi
+
+cat > /etc/profile.d/http_proxy.sh<<EOF
+export http_proxy='$http_proxy'
+export HTTP_PROXY='$http_proxy'
+EOF
+
+if test -f /etc/yum.conf; then
+  sed -i -e '/proxy=/d; /http_caching=/ d' /etc/yum.conf
+  sed -i -s '/\[main\]/ a http_caching=packages' /etc/yum.conf
+  sed -i -s '/\[main\]/ a proxy='$http_proxy /etc/yum.conf
+
+  sed -i -e 's/^enabled=.*/enabled=0/' /etc/yum/pluginconf.d/fastestmirror.conf
+
+  if [ ! -f /var/tmp/yum-clean.stamp ]; then
+    pgrep -f yum || yum clean all || true
+    touch /var/tmp/yum-clean.stamp
+  fi
+fi
--
libgit2 0.21.2