Linux Forums unreachable.

Tom H tomh0665 at gmail.com
Wed Feb 24 14:04:20 UTC 2010


> 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?

Great summary and suggestions - although I doubt that it has other
ports open. It is not configured for https for example (it just has a
RHEL default apache page at that port).

I do get a response from "traceroute -T" from home, work, and a US
server to which I can ssh to temporarily so the lack of response is
definitely Ray's problem and not a general linuxforums.org one.




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