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Our server is on a corporate network, which requires corporate proxy authentication (e.g. enter corporate username and password). This is not an issue on the Windows machines on that network - when a web browser is opened the user is prompted to authenticate. However, when using a browser on Linux, the user is not prompted to authenticate, the browser simply shows a message saying authentication is required.

Internet Access would be useful

At the moment I have to walk to my desk on another floor, if I need to look something up, because I cannot get Internet access from this machine, since I cannot (or do not know how to) authenticate. It would be useful to have the ability to authenticate, so I can use a web browser.

Packages cannot be updated

When I attempt to perform updates using sudo apt-get update or sudo apt-get install [package], there are errors, which I believe are caused due to lack of authentication.

After performing sudo apt-get update, I get errors like W: Failed to fetch [link] 401 Authorization Required. (For some reason some http://us.archive.ubuntu.com trusty/ sources work correctly, and some throw the same error).

This is a major problem, as I need to be able to update packages on the server.

  • I have installed cntlm via sudo apt-get install cntlm (it works from one of the few Ubuntu repositories that randomly work).
  • I edited the configuration at /etc/cntlm.conf and added my username, the domain and the proxy.
  • I started the service (sudo /etc/init.d/cntlm start).
  • I tested the service (sudo cntlm -I -M http://www.google.com/) and the response was Config Profile 1/4... Auth not required (HTTP code: 307) Your proxy is open, you don't need another proxy.
  • I tried performing sudo apt-get update again and still receive the same error message. (401 Authorization Required)
  • (Whoops! My mistake! I see I need to configure apt proxy settings manually...)
  • I added the line Acquire::http::Proxy "http://localhost:3128"; to /etc/apt/apt.conf.
  • I restarted cntlm. (sudo /etc/init.d/cntlm stop, sudo /etc/init.d/cntlm start)
  • I performed sudo apt-get update ... and it hit 0% [Waiting for headers] [Waiting for headers] [Waiting for headers] [Waiting f - and just stopped there.

Steps Taken (after asking)

  • I performed sudo apt-get clean, before performing sudo apt-get update - this started working and then stopped at 19% [Waiting for headers]
  • I performed sudo apt-get clean again, before performing sudo apt-get update - this started working and then stopped at 0% [Waiting for headers]
  • I tried this a third time (sudo apt-get clean, sudo apt-get update) and it stopped at 20% [Waiting for headers]

  • I researched this subsequent problem and found an answer on AskUbuntu, suggesting this may be an issue with IPv6 causing ICS to halt for a while, when it receives concurrent connections.

  • I checked the /etc/sysctl.conf file and discovered the IPv6 already appears to be disabled... (The lines net.ipv6.conf.all.disable_ipv6 = 1, net.ipv6.conf.default.disable_ipv6 = 1, and net.ipv6.conf.lo.disable_ipv6 = 1 are already in the config file.)
  • (I'm now drawing a bit of a blank! The symptoms match the hypothesized IPv6 issue, however, if it is already disabled that doesn't seem to be able to be the cause)
  • I performed sudo apt-get clean and sudo apt-get update a fourth time (What the hell - why not?) and it hung on 24% [Waiting for Headers] this time, but first it hit a bunch of repositories. A repository which used to trigger errors did not do so now (http://cran.rstudio.com trusty /) but one which used to trigger errors now triggered a different error, Received HTTP code 501 from proxy after CONNECT.
share|improve this question
Try entering the IP of the gateway/proxy in to your browser. –  Gabriel Jul 10 '14 at 10:28
I entered the proxy name into the browser and it gave the same corporate error page but the error was a GATEWAY_TIMEOUT. –  Eilidh Jul 10 '14 at 10:42
Do you still have the same problem? Are you using Unity or something else? Have you tried adding the proxy settings in the proper fields? –  Braiam Aug 16 '14 at 0:57

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