Connection works, not internet

[louk]

Hello everybody !

I'm on a Debian 8 Jessie and all was working well at start (well, not really, as you will see soon). This computer has been given to me to install a Moodle test server and create a plugin that will use Flash (I haven't the choice for Flash ).
Neither Flash nor the update command (just below) was working

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sudo update-flashplugin-nonfree --install

(I get a wget error, a known bug) and the command said to look at this manual. I tried things in the read order and first, I have set http_proxy to a value like http://IP_address:port (unfortunately, I don't remember this value, nor how did I find it). And it didn't work.
After that, I solved the problem by adding an alternative by following what's described at "Manual update" section (but I still have the wget error, so I'll have to update manually each time needed).
Flash was working, internet too.

Today, I started the computer and internet wasn't working anymore. I say internet, but not the connection.
I can install anything in the terminal with the usual apt-get command, but no internet navigator is willing to load any external website.

Note : I'm at the ENSTA (Ecole Nationale Supérieur de Techniques Avancées - Superior National School of Advanced Techniques) of Brest (France) for my internship and they use a proxy server. Thus, we have to set up firefox to "Auto-detect proxy settings for this network" and I don't know this Proxy, but I probably can ask to their informatic service and get the proxy settings.
Note 2 : I tried several cables which worked on my personal computer, nothing changed. I rebooted, then I rebooted again after deleting the line in /etc/apt/apt.conf that was like :

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Acquire::http::http://[[user][:pass]@]host[:port]/

Nothing changed : apt-get install works well, not navigating on the internet.

PS : I use Linux since I'm in high school and I learned a lot by myself but I don't really master any skill on Linux.

[louk]

When I've set a value to http_proxy, I typed "http_proxy=..." into the terminal. And even after rebooting, http_proxy has still a value. When I type "echo $http_proxy", I get "http://192.168.1.10:3128".
Is it an old value that was there before I do anything ? I don't think so, because I remember that I've typed "echo $http_proxy" before doing any changes, and it had no value (the command had just printed a newline). Or not.
Crap, I can't remember if echo printed a newline before I do anything, or after I tried to set http_proxy and then I've set http_proxy again to nothing (I was obviously expecting no effect after rebooting or disconnection, but as I said, I try stupid things because I'm not a professional with Linux).

EDIT : I tried some pings, and they work in both sides.
The tower computer has the IP address 172.20.10.240 and mine (portable PC) has 172.20.13.16.
I did "ping 172.20.10.240" on my PC and "ping 172.20.13.16" on the other computer. Both commands worked.

[sgian]

If you try a different browser like chromium, and autodetect the proxy settings, does that work to load internet pages? If so, then it is a firefox setting. If not, it is probably a proxy setting.

[louk]

I tried that, even with Links (console navigator) it didn't work.

And now (since the day after navigators were failing but not apt-get), the apt-get install command fails too : "couldn't resolve deb.debian.org". At least it's more logical.
I don't know what to do but re-install Debian (there are no important data).

[Princess Midna]

Yes, you will need to ask for the proxy settings.

[louk]

I thought about that and I'm not sure of how it's done.
I found this article and this one, is one trustful ?
In the meantime, I'll ask what are these proxy settings and hope I'll finally get internet working everywhere.

BTW, I can surf the web (auto-detect settings in Firefox) on my personal laptop, but a gradle build in the terminal failed (it needs to download dependencies). I solved the problem by doing it at home, but I'll probably have to do similar commands later.

EDIT :
The weird thing is that when I type "echo $http_proxy", I get "http://192.168.1.10:3128" on my test PC. On my laptop, I just get a newline (that is, an empty string).
I tried to find where the hell is defined http_proxy without success.

I added this line in /etc/apt/apt.conf : "Acquire::http::Proxy http://proxy.ensieta.ecole:8080/;" and typed "apt-get install kate" (I don't need Kate, it's just for test).
I got the error : Could not resolve "proxy.ensieta.ecole".
I modified the above line to : "Acquire::http::Proxy http://my_username:my_pass@proxy.ensieta.ecole:8080/;", I got the same error.

I lost my USB key, so I can't make a liveUSB for now...

[sgian]

It looks like port 3128 is the correct port unless it has been changed, so try changing port 8080 in your /etc/apt/apt.conf to 3128. I found this link while searching for proxy settings for your school, scroll down to the proxy section and hopefully that example works...
http://www.ensta-bretagne.fr/lebars/Share/Ubuntu.txt

Here is how your school says to set the proxy but it looks like they use automatic settings even for linux https://www.ensta-bretagne.fr/jaulin/sw ... config.pdf

[debiman]

have you actually tried to ping a domain?
like

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ping archive.org

?

[shep]

Along another tract, but perhaps DNS resolution is failing. You can quickly check by pinging Google's DNS server at 8.8.8.8

[louk]

Hey everybody ! In France, we got a long week-end (Thirsday to Sunday) so I forgot to check this forum. I've started to develop the Moodle plugin, I was bored by this issue.
Thank you all for your help, I'll try to add lines given in the Ubuntu.txt file that sgian found (thanks !).

I tried to ping several web servers external to the school but it failed. I don't remember which but I remember I tried several things without success.

For now, I'll try that sgian suggests and I'll give news ASAP.

[dasein]

I tried to ping several web servers external to the school but it failed.

Then it would have given you an error message, which you rather conspicuously chose not to include. Do you imagine we are capable of mind-reading>

I tried several things without success.

I have a similar problem with my car not starting. I've tried several things without success. What should I do next?

In case it isn't obvious, you haven't provided nearly enough detail for folks to help you, and what little information you have provided is self-contradictory. If you're serious about getting help, then you need to get serious about diagnostics; if you're simply trolling, then do it someplace else.

[louk]

Have you read all my posts ? Because I gave a lot of information before that one.

If I wasn't clear and if I haven't given any details, it's because I considered it wasn't usefull. I tried to ping several servers like Google and it didn't work. I tried to ping between my laptop and the school computer, it worked.

Anyway, thanks to sgian, I resolved all my problems. Tus, no need to reinstall Debian.
I've followed the Ubuntu.txt he linked in his post. I've added this lines in /root/.bashrc and ~/.bashrc :
export https_proxy=https://192.168.1.10:3128
export http_proxy=http://192.168.1.10:3128
export ftp_proxy=ftp://192.168.1.10:3128
export no_proxy=localhost,127.0.0.0/8,ensieta.ecole,ensieta.fr,ensta-bretagne.fr

I've added this lines in /ect/apt/apt.conf :
Acquire::https::Proxy "https://192.168.1.10:3128";
Acquire::http::Proxy "http://192.168.1.10:3128";
Acquire::ftp::Proxy "ftp://192.168.1.10:3128";

And now it works. I've set this proxy in Firefox ESR settings and it works too.

So, a great thanks to everybody and have a good week-end

EDIT : Is there any button to put this subject to "solved" ?