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No internet

Posted: 2019/10/18 07:53:36
by mukhos
Hi, I am using CentOS 7 on my local workstation.
For past 4 days I am not able to access the internet.
I will list down the symptoms and what I have tried so far.

The workstation is connected through LAN in my institute and I can access the institute webpage.
However, i can not access any page outside say google through the proxy authentication.
I can use my windows laptop through the same port successfully.

I can ping 8.8.8.8 as well as google.com
with 0% packet loss.

I tried many things available on the forums and could get internet yesterday but then as the proxy kicked off the session
I lost again internet connectivity.

I used both firefox and chrome with clearing cache,history, data etc.

I disabled and enabled NetworkManager also
When I disable NetworkManager nothing works but after enabling I see LAN icon with red cross but on clicking it shows IP4 addres and GATEWAY

after I issue command systemctl restart Network then red cross goes away but IP4 is now shown as 0.0.0.0

In both the above cases I cant open any site in browser.

Please help as I am frustrated after 4days of trying everything.

Let me know if you require any other output.

Re: No internet

Posted: 2019/10/18 11:40:55
by stevemowbray
You need to ask whoever is in charge of the network at your institute.

Re: No internet

Posted: 2019/10/18 12:01:59
by lightman47
It sounds like your proxy setup or firewall settings in CentOS got messed perhaps???

Re: No internet

Posted: 2019/10/18 13:58:49
by mukhos
Unfortunately, I do not have support from the institute as they say its OS issue.

I do not know what got messed up.

I am confused whether to use NetworkManager or network.service.

I disabled firewall and that doesn't solve the problem.

Please suggest

Re: No internet

Posted: 2019/10/18 15:07:34
by lightman47
Yeh - probably is. Turn the firewall back on.

Is there anything in /var/log/messages when you try it? Also, if it were me, I'd fire up the working Windows and note all the correct proxy settings. Then I'd compare with the CentOS proxy settings. This may not help, but it's worth a shot.

Re: No internet

Posted: 2019/10/18 16:25:34
by jlehtone
mukhos wrote:
2019/10/18 07:53:36
Hi, I am using CentOS 7 on my local workstation.

The workstation is connected through LAN in my institute and I can access the institute webpage.
However, i can not access any page outside say google through the proxy authentication.

I can ping 8.8.8.8 as well as google.com with 0% packet loss.
In other words, there are no problems with the network connection.

Your institute blocks direct access to external (http/https ?) sites and requires you to use
a (http?) proxy. Your issue is in how to use the proxy that requires authentication.

Presumably, you can either configure an individual application (like browser) to connect
to the proxy or set Gnome/desktop/NetworkManager to offer the proxy settings for the
applications.
(Something like https://help.gnome.org/users/gnome-help ... xy.html.en )

As an example, the Firefox has four options:
1. No proxy
2. Automatic proxy settings
3. Use system's proxy settings
4. Manual proxy configuration
5. Fetch proxy settings from URL

Can we assume that you have gone through those options according to your institution's instructions?
Do they have instructions for diagnosing authentication issues?


PS. "using CentOS 7" on CentOS 8 Forum?

Re: No internet

Posted: 2019/10/18 18:02:24
by mukhos
Your institute blocks direct access to external (http/https ?) sites and requires you to use
a (http?) proxy. Your issue is in how to use the proxy that requires authentication.
Yes. And I do not get the prompt asking user id and password for proxy authentication.

One strange thing is I can ping 8.8.8.8 but not the proxy server.
Presumably, you can either configure an individual application (like browser) to connect
to the proxy or set Gnome/desktop/NetworkManager to offer the proxy settings for the
applications.
I tried both with the suggested institute settings but doesn't work


Also compared the gateway and its correct for windows laptop on the ethernet.

I am on KDE and somebody said that network issues are common in KDE

I am new to CentOS and I feel its much complicated as compared to Ubuntu which I have used for some years till now.

Sorry I didn't note that its Cent OS 8 forum.

Re: No internet

Posted: 2019/10/20 16:04:35
by mukhos
Looks that some issues can't be resolved!

Format and reinstalled.

Thanks for the suggestions.