At work, I need to connect to a customer network via VPN at times, and doing so, I need to set a proxy. While IE picks that up automatically (the standard "default internet proxy"), Firefox doesn't, which is a pain.

Yes, I know - I can have Firefox look at my DOS environment variables like http_proxy and use these - but that's still a pain.

Is there an extension for Firefox that will pick up the default internet proxy set by Microsoft (it's stored in the registry, after all) and use it, when it's set? That would make my life a LOT easier!

If not - anyone care to write such an extension? :-) Sounds like that shouldn't be all too hard, really.....



Firefox used to have the add-on Quickproxy, but it's not ready for 3.5 yet...

  • I used QuickProxy, and it's a good workaround - but still a workaround. Firefox still doesn't automatically pick up the system default proxy..... – marc_s Jul 20 '09 at 14:00

You can try using a Firefox plugin like FoxyProxy to do this. Another way to do this is to create an entry in your systems routing table which differentiates between VPN address space and internet address space. If you have it set to route anything not going to the VPN to your local default gateway, then you will not need to worry about the internet proxy settings being used by your customers. Firefox will just work all of the time.

Type "Route Print" in a CMD shell to get started...

  • trouble is - when I'm dialed up into that VPN - ALL traffic must go through the proxy. I can't keep my "normal" web traffic away from it - it HAS to go through the proxy, or it won't work :-( – marc_s Jul 20 '09 at 14:03
  • So, this is the customer's policy, right? – Arjan Jul 20 '09 at 14:48
  • not even sure if it's a policy per se - I just noticed that when I'm dialed up to their VPN, trying to connect to any site requires using their proxy - all other communication appears to stop. – marc_s Jul 21 '09 at 5:04
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    You've got me confused now. From a technical point of view, the proxy is needed because Windows by default routes all the traffic through the VPN, like I wrote in my earlier answer. But this setting is easily changed. From a policy point of view, the customer may not want you to make this change though. On the other hand: your own employer's policy might actually forbid you to send all traffic over the customers VPN server. So, back to my answer: do you actually want to send all traffic over the VPN connection? – Arjan Jul 21 '09 at 20:08

If you set your proxy settings to "auto-detect settings for this network", this should work on firefox too. You need to have the ip assigned by dhcp for this to work.

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    Nope that doesn't seem to work. I just dialled into the VPN, and while MS IE picks up the new proxy automatically from the registry, Firefox still fails to connect to www.google.com, even after I've set this "auto-detect settings" option :-( – marc_s Jul 21 '09 at 7:45

You can use the automatic proxy configuration, but you need to setup the infrastructure to understand it using DHCP and DNS.

On startup, the browser will first check DHCP options for the proxy config host. If not present, it performs a DNS query for host "WPAD". If found using one of those methods, it does an HTTP GET for /proxy.pac, which is the Proxy auto-config script.


  • Thanks - but this is an external customer and I have no control over their IP department (and no hope to get them to do something like this for me :-( ). – marc_s Jul 20 '09 at 14:01
  • It sounds to me that this task is best left up to that company's IT department. This is an infrastructure support issue if the desktop browsers are not pre-configured for Internet access. – spoulson Jul 20 '09 at 14:59

At work, I need to connect to a customer network via VPN at times, and doing so, I need to set a proxy.

I think you actually might not want to use that proxy, as I expect you do not want to send ALL traffic through the customer's server. The fact that you cannot browse without that proxy is probably an indication that you are actually sending ALL traffic through the VPN.

When all traffic is sent through the VPN, then even "normal" internet access (like web browsing or maybe even sending and fetching email) is routed through the remote VPN server. This might be useful when traveling in some countries that filter certain web sites. And as the VPN connection is encrypted, using it for all traffic might also be more secure when not knowing who can listen in to the network that is used to connect to the internet (hotel, internet café, Starbucks WiFi, ...). Above all: it might be a bit more secure as any "hacker" (trojan horse, spyware) who has gained access to your workstation will be disconnected as soon as the VPN connection is started, thus not exposing the server's network to that security threat. It depends on the set up of the VPN server whether or not such unwanted trojan traffic could be re-established through the VPN server. To avoid security issues, internet access through the VPN server is often simply disallowed.

So, sending all traffic through VPN may very well be preferred in many occasions, and often one should NOT try to bypass any limitations as set up by the administrator. But I wonder if that is true while connecting to a customer's VPN server.

I would say:

  • Just keep the VPN connection alive as short as possible, and while connected do not use the connection for anything else. (Browsing, email, instant messaging, ...; do you want your customer to be able to track your traffic?)
  • If you really need to use other resources on the internet, then your customer's policy might tell you to use their proxy. If so, then indeed you have no choice. (I assume that proxy is theirs, for otherwise you wouldn't be able to use it without disabling sending all traffic through the VPN to start with, unless it has some local address that might not be routed through the VPN connection? If it is not theirs, but just a way to avoid blocked ports, then think twice...)
  • If the customer is OK with not using their proxy, and if you really need the browser, and if you're sure your workstation is secure: disable sending all traffic through the VPN.

Windows by default sends all traffic over VPN, but a Mac does not. (On a Mac, the Advanced button shows an option "Send all traffic over VPN connection". Windows has a simular option, but I can't tell you where to find that exactly.)

EDIT: changed the recommendation.

  • sure - but how do I make Firefox automatically pick it up, when I activate it?? – marc_s Jul 20 '09 at 14:02
  • Just wanted to make sure you really WANT to use that proxy. – Arjan Jul 20 '09 at 14:26
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    Yes, I have to - when I'm connected to their VPN, ALL traffic MUST go through their proxy - they won't allow anything else :-( – marc_s Jul 20 '09 at 15:45
  • Well, from the customer's point of view such a policy makes sense. It's easy to bypass, but I guess one should respect the customer's wish. – Arjan Jul 20 '09 at 15:51

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