I've set up both DHCP and DNS servers for WPAD, and chromium finds the proxy server automatically. However, when automatic proxy configuration is set in System Settings, a message "Could not find a usable proxy configuration script" appears, even though /usr/lib/kde4/libexec/kpac_dhcp_helper is setuid and correctly returns http://server.home/wpad.pac, and a DNS CNAME wpad.home is set in the DNS server. If I set the proxy auto configuration URL, then everything works fine. This problem is especially annoying, because, when auto configuration fails, the first DNS request for a domain name blocks the program for more than 10 seconds. This makes konqueror and akregator almost impossible to use. Reproducible: Always Steps to Reproduce: 1. Set automatic proxy configuration. WPAD is known to work, as chromium finds proxy configuration automatically. Actual Results: A message "Could not find a usable proxy configuration script" appears and direct connections are used. Some DNS requests make the program block for more than 10 seconds. Expected Results: Proxy configuration should be detected automatically and used.
The filename 'wpad.pac' will only work for the DHCP setup. For DNS setups the filename has to be 'wpad.dat'. See https://projects.kde.org/projects/kde/kdelibs/repository/revisions/d122c2bb104b434cbe98b1e60b20a60e24631e4b/entry/kio/misc/kpac/README.wpad The problem could be that the code that attempts to automatically discover the PAC could not successfully locate the kpac_dhcp_helper file. I have attached a small C++ file. Can you compile it on your system (you need to install gcc), run it and see if it outputs the same thing as running kpac_dhcp_helper ?
Created attachment 76852 [details] simple test file... instruction on how to compile is inside the file...
> /usr/lib/kde4/libexec/kpac_dhcp_helper http://server.home/wpad.pac > ./test_kstandarddir PATH: "/usr/lib/kde4/libexec/kpac_dhcp_helper" However, both konqueror and rekonq freeze when resolving DNS the first time, and I'm fairly certain that the proxy settings are not followed, because kde applications connect to the proxy server only when the proxy auto configuration URL is set, while chromium connects via proxy always, using either wpad.dat or wpad.pac! As reported previously, I've set both DHCP and DNS WPAD, and the web server serves both wpad.dat and wpad.pac, which are symlinked.
Dawit, does comment #3 provide the requested information?
(In reply to comment #4) > Dawit, does comment #3 provide the requested information? Yes, but it does not really help isolate the problem. @reporter If kpac_dhcp_helper returns the proper URL as you stated, then that URL should be downloaded and used to configure the proxy. For some reason that does not seem to be the case for you. Can you compile and post the output of the updated C++ program. Instructions are included in the file.
Created attachment 77061 [details] updated simple test file...
~> ./test_kstandarddir domain name: "home" kpac_dhcp_helper: "/usr/lib/kde4/libexec/kpac_dhcp_helper" http://server.home/wpad.pac RESULT: ""
(In reply to comment #7) > ~> ./test_kstandarddir > domain name: "home" > kpac_dhcp_helper: "/usr/lib/kde4/libexec/kpac_dhcp_helper" > http://server.home/wpad.pac > RESULT: "" Ahh. Now I see the problem. It is caused by how KProcess works! By default it forward the standard output and error channels to the respective channels of its parent process! We do not want that in our case or "RESULT" will be blank as your output shows. Thanks for running the test program and providing the output.
Oh and the DNS based lookup also fails for you because your domain name does not contain a '.' ("home") which is also a silly logic error!
Git commit 9b1dc2999df1d3205a453a2c2e294fba79e1915d by Dawit Alemayehu. Committed on 09/02/2013 at 20:56. Pushed by adawit into branch 'KDE/4.10'. Fixed both DHCP and DNS based PAC/PAD lookup. The DHCP based lookup was completely broken while DNS based lookup only worked if the domain name of your machine contained at least one '.' FIXED-IN: 4.10.1 M +8 -4 kio/misc/kpac/discovery.cpp M +1 -1 kio/misc/kpac/proxyscout.cpp http://commits.kde.org/kdelibs/9b1dc2999df1d3205a453a2c2e294fba79e1915d
Something that I found out recently: the fact that DNS based lookup works only for domain names with a dot may be a security feature according to http://en.wikipedia.org/wiki/Web_Proxy_Autodiscovery_Protocol, because otherwise failure to set up a wpad name in the local network may open it to man-in-the-middle attacks, e.g. for the network under example.com the next step is wpad.com, which might be malicious.