Help

Ahhh...the age old problem, users who cannot browse the net. I believe the phrase starts " if I had a dollar for every time......"

But seriously, there are quite a few different issues which could affect the Internet browsing.
Firstly, lets understand how your users connect to the Internet.

We will consider a dial up client in this example.

Each client's web browser (hope we are all using Firefox), is configured to connect to the Internet via a Proxy server. The Proxy server software which runs on the Linux server is Squid. So when your user opens their browser, it sends a request to the Squid program. The Squid program then checks if the dial up connection is active, if its not, the dial up connection is activated, and the server dials up to your ISP.
Once it is connected, Squid then fetches the URL which was requested, caches a copy and sends it on to the client.
If another user requests the same page, Squid doesn't need to fetch the URL from the web, as it already has a cached copy.

So if we now understand basically how Squid works, it will be easier to troubleshoot why your users have problems.

The main reason that comes up time and time again, is that the server cannot dial up to the ISP. Which sounds obvious to some people, but still eludes most.
Therefore, the first thing to check, is whether your Linux server is actually managing to dial into your ISP. PING is your friend.

ping etrn.zol.co.zw
or
ping etrn.yoafrica.com

The above command doesn't mean that you are connected. You must actually see the replies first.
If you are getting good replies, then the next obvious problem may be that the Squid program has stopped running for some reason. ( this happened quite often on older versions of Linux,with CentOS it is very rare.)

Now you will ask " but how do I check if Squid is running or not " Very easy...

[root@server ~]# service squid status
squid (pid 3435 3433) is running...
[root@server ~]#

easy as pie....
But!!! What happens if....

[root@server ~]# service squid status
squid is stopped
squid: ERROR: No running copy
[root@server ~]#

never fear....eNet is here... you just need to start the service.

[root@server ~]# service squid start
Starting squid: . [ OK ]
[root@server ~]#

Get your users to check their browsing again, all will be good.

Sometimes the Squid proxy will misbehave and it will refuse to start up...this is covered in the next section.