ADSl routing issues and IE6

[Harryinashed]

Hi all,
I have set up my Wireless network router to share my ADSL
internet connection. I am using a seperate modem which is
then connected to my wireless router. I have no problem
viewing most pages and downloading files. The problem
occurs when i try to view hotmail or yahoo email accounts
and microsoft update webpages. These simply refuse to
work and come back with a DNS error. I have treid
removing the hardware firewalls on both the modem and the
router and this makes no difference. If i connect another
adsl modem to the computer (an old modem that can't
connect to a router) and then the problem disappears.
This is a network wide problem and can be solved on any
machine by using a standalone modem. I have also tried
removing the XP firewall along with the other 2 firewalls
and this makes no difference (the xp firewall allows me
to access anything with my old modem). Does this mean
that there is a problem with the setting of my new adsl
modem, if so why are only certain sites affected, or is a
problem with the way the computers talk to the router? I
am really stuck on this issue and no one seems to be able
to help (.

Thnaks in advance,
Harry
..

 

[Robert Aldwinckle]

(an old modem that can't connect to a router)

Looks as if your router could be the culprit. (E.g. for MTU size issues)

<title>KB314825 - How to Troubleshoot Black Hole Router Issues</title>

The problem with the diagnostics suggested by that article is that
too many sites are now blocking ICMP packets to guard against
the morons who conduct their "denial of service" exploits against
major sites. Hence, I suspect you will find that both Hotmail and
Yahoo will be blocking pings.

There are two possible circumventions that I can think of which
might be sufficient for you to do the same type of testing though.
First use tracert to see if there are intermediate nodes along
the paths to those sites which still do accept pings.
Then you could try the MTU test suggested by the article using
those IP addresses instead. BTW I would also use the n -1
switch because it is sufficient to know that one packet works.

The second idea is to use a telnet simulation on both of your
links and see if the responses are truncated. (This is just a poor
man's packet trace so if you have a packet capture tool such
as netcap or Ethereal you might find a packet formatter's
statistics easier to interpret.)

You can also get some Q&D statistics from netstat.
Here is an excerpt of some previous instructions for that:

<excerpt>
If you don't have a packet tracer and you don't get any input in telnet.txt
(capture file from above test) a better diagnostic that you will have than
watching lights flash is the following command line procedure. Do this
in a separate command window because the telnet test is part of it.

netstat -s >before.txt

Now do the telnet test in the other command window.
Wait for something to happen but don't wait so long that
other things start happening and messing up the statistics.
Then switch back to the second command window and finish with:

netstat -s >after.txt
fc before.txt after.txt >diff.txt
notepad diff.txt

</excerpt>

(The extra command window is mostly for convenience
because of the telnet command in the middle.)


You may have to do this test a few times on each link
to be sure that you know what average statistics look like
for your test. Then compare both link's average statistics.
Note: even though you can use one link with IE you would
not want to do that in this case because it would not be
comparable with what you could do on the other link.
So use telnet to make and capture one request each time.


Good luck

Robert Aldwinckle