Re: Linux Forums unreachable.



Markus Schönhaber wrote:
24.02.2010 02:51, Ray Parrish:


Markus Schönhaber wrote:



That's indeed strange: UDP packets do reach the target, TCP packets don't.

@Ray: you don't have any packet filter active on your machine or your
DSL router, do you?


No, but I note that the router portion of it is blocking one specific
web site that does not match linuxforums.org. I suppose I could remove
that entry, and retry if you think that could be the problem.


OK, let's see what we do know:
- you can't establish a TCP connection to port 80 at www.linuxforums.org,
- the problem is not caused by a DNS failure,
- UDP packets do reach www.linuxforums.org,
- TCP packets don't
In fact, the last point isn't exactly true. All we know is that
traceroute -T doesn't receive a response from www.linuxforums.org. That
could mean that either the probe itself gets thrown away on the server
side or that the probe does reach the server but the response to the
probe is dropped somewhere.

Judging from the above, I can imagine two possible causes of the problem:
1. linuxforums.org/theplanet are - for some reason unknown to me -
indeed blocking you (or an IP range which contains the IPs you are
assigned) from access to their site.
2. Something at your side (DSL router/computer) is throwing away some
network packets thus making it impossible for you to access
www.linuxforums.org.

If 1. is true, there's not much you can do about other than, for
example, asking them about the problem via mail or on #linuxforums IRC
channel on freenode.
If there's another QWest customer in your neighbourhood and you could
make them check their access to www.linuxforums.org, that would give a
hint too.

If 2. is true, you have to find out what exactly it is that blocks
communication with linuxforums.org.
What I'd try:
- Boot the machine from a LiveCD and check if it makes a difference. If
it doesn't, this pretty much rules out your machine as source of the
problem.
- Change the router's configuration to not block anything and check if
it makes a difference.

While not exactly helping to find the culprit, it might nevertheless be
interesting to see if the problem is specific to port 80. I. e. if you
telnet to a different port (21, 53, 443, 8443 for example seem to be
open on linuxforums.org) will a connection be established?

Other than that, I don't have any ideas, sorry.

Hello again,

I have a dual boot machine, and from Windows XP I can connect to
linuxforums.org easily.

Here are the non-connecting results of the other ports -

ray@RaysComputer:~$ telnet www.linuxforums.org 21
Trying 174.132.123.98...

ray@RaysComputer:~$ telnet www.linuxforums.org 53
Trying 174.132.123.98...

ray@RaysComputer:~$ telnet www.linuxforums.org 443
Trying 174.132.123.98...

ray@RaysComputer:~$ telnet www.linuxforums.org 8443
Trying 174.132.123.98...

ray@RaysComputer:~$

I tried to change my settings for the router to remove the one blocked
web site while in Windows, but it would not load any other pages after
loading the log in, then the routing table page.

Something in Ubuntu is blocking me from reaching linuxforums.org, and I
would like some coaching on all of the possible things that can block a
certain web site from being reached.

Could it be a firewall rule? I have some ports blocked, and have a
blacklist policy in effect, as opposed to white listing traffic.

Thanks, Ray Parrish

--
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Writings of "The" Schizophrenic, what it's like to be a schizo, and other
things, including my poetry.
http://www.writingsoftheschizophrenic.com



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