New T-1 Network Weirdness, only with - CERTAIN - network apps

John David Eriksen · 05-16-2003, 12:31 PM

Please read carefullt as this is really weird.

Client just installed new T-1 circuit.. EVERYTHING works fine. They have their own Router (configured plain vanilla) DNS, Email, FM, Web, NNPT servers timbuktu to manage. As near as we can see EVERYTHING work perfect...
E X C E P T:

1) MSIE cant find => c e r t a i n <= web sites (the most notable is apple.com itself). Safari will find them but ONLY after loading the URL the second time (first time it also says cant find it) But then it ALWAYS finds it on the secord try.

2) ANY (and I am saying any) internet search conducted with SHERLOCK using any text string or individual word, will unexpectedly quit the app, otherwise SHERLOCK works fine (so its net search only.

3) Any attempt to access the iTunes music store will also unexpectedly quit the app. However every other aspect of iTunes works fine INCLUDING the Internet Radio Channel....!!!

We see no other weirdness in the system anywhere using any other application.
______________
This is NOT THEIR installs of 10.2.6, (all G4s...) AND I brought in => MY <= PowerBook and the second I plug into their ethernet my PowerBook also starts this behavior...!!!! So it not their machines

There is no Firewall or Proxy anything and the only filtering is ICMP (ping) and that is filtered by their upstream provider... and as I said above their own Router (an Ascend Max, is configured plain vanilla and works fine.
_____________
I don't understand what about the network would cause these (and only these) apps to crash (as opposed to just not going somewhere and getting what you asked for.. and... it happens INSTANTLY. Namely what ever it doesn't like... it REALLY doesn't like it... Yet everything else works bloody well PERFECTLY...!!!

Anyone have any ideas about what might be going on here... please.. I am running out of list items to check

Thanks in advance guys

hayne · 05-16-2003, 01:01 PM

I have no idea why the applications would crash.

But to figure out what is going on, I would recommend you use some lower-level network tools.

When you say that the web browsers "can't find" a site, does it work if you use the IP address instead of the name?

One notable thing about apple.com is that they use the Akamai network - maybe this is the common link in the troublesome web sites?

Some network tools to try (to get clues on what is happening) - you use these in Terminal:

ping
- tests basic network connectivity (but relies on ICMP)

traceroute
- shows the route over the Internet to a given machine

dnstracer (I think I got this via fink)
- shows what DNS server is being used

tcpflow (I got this via fink)
- shows the contents of network packets being transmitted and received (easier to use than tcpdump which is already on your machine)

mervTormel · 05-16-2003, 03:17 PM

sounds like all your protocols that crap are HTTP, so i'd have a dig in that direction.

HTTP proxy (privoxy) here swats iTMS, sherlock. not catastrophic, but just no results and no messages.

aixccapt99 · 05-16-2003, 04:02 PM

tcpflow is great--definitely recommended. That should let you see whether the http requests are ever going out or not, and if any reply is coming back.

My other thought is some problem in the DNS lookups for these particular sites--is their DNS caching behaving strangely, or is lookup failing in a really bad way for these sites? I don't know enough about DNS to get into detail, but that would fit your diagnosis of a LAN-specific and www-site-specific but non-machine-specific problem. And you did say they run their own DNS...

Don't know why bad DNS info could make iTunes/Sherlock crash, but maybe there is a bug in a code library they share (but Safari/IE don't use)?

Let us know if you figure it out...

Joe

yellow · 05-16-2003, 04:28 PM

I've seen similar discussions about browsers not being able to load sites properly. Apparently the naughty bunny was the router. The solution there was router firmware upgrades.

hayne · 05-16-2003, 11:49 PM

I recalled some discussion of an issue with certain web sites that resembled what you describe. I think this discussion at Macintouch of a problem with DNS and Akamai on 10.2.4 is what I was remembering:
http://www.macintouch.com/mosxreader10.2pt59.html
(search for AKamai - it's in a letter from Michael Rose)

05-16-2003, 12:31 PM	#1
John David Eriksen Triple-A Player Join Date: Jan 2002 Location: St Petersburg Fla Posts: 115	New T-1 Network Weirdness, only with - CERTAIN - network apps Please read carefullt as this is really weird. Client just installed new T-1 circuit.. EVERYTHING works fine. They have their own Router (configured plain vanilla) DNS, Email, FM, Web, NNPT servers timbuktu to manage. As near as we can see EVERYTHING work perfect... E X C E P T: 1) MSIE cant find => c e r t a i n <= web sites (the most notable is apple.com itself). Safari will find them but ONLY after loading the URL the second time (first time it also says cant find it) But then it ALWAYS finds it on the secord try. 2) ANY (and I am saying any) internet search conducted with SHERLOCK using any text string or individual word, will unexpectedly quit the app, otherwise SHERLOCK works fine (so its net search only. 3) Any attempt to access the iTunes music store will also unexpectedly quit the app. However every other aspect of iTunes works fine INCLUDING the Internet Radio Channel....!!! We see no other weirdness in the system anywhere using any other application. ______________ This is NOT THEIR installs of 10.2.6, (all G4s...) AND I brought in => MY <= PowerBook and the second I plug into their ethernet my PowerBook also starts this behavior...!!!! So it not their machines There is no Firewall or Proxy anything and the only filtering is ICMP (ping) and that is filtered by their upstream provider... and as I said above their own Router (an Ascend Max, is configured plain vanilla and works fine. _____________ I don't understand what about the network would cause these (and only these) apps to crash (as opposed to just not going somewhere and getting what you asked for.. and... it happens INSTANTLY. Namely what ever it doesn't like... it REALLY doesn't like it... Yet everything else works bloody well PERFECTLY...!!! Anyone have any ideas about what might be going on here... please.. I am running out of list items to check Thanks in advance guys __________________ ___________________________________ John David Eriksen System Administrator Suncoast Network Services ___________________________________

05-16-2003, 01:01 PM	#2
hayne Site Admin Join Date: Jan 2002 Location: Montreal Posts: 32,473	network tools I have no idea why the applications would crash. But to figure out what is going on, I would recommend you use some lower-level network tools. When you say that the web browsers "can't find" a site, does it work if you use the IP address instead of the name? One notable thing about apple.com is that they use the Akamai network - maybe this is the common link in the troublesome web sites? Some network tools to try (to get clues on what is happening) - you use these in Terminal: ping - tests basic network connectivity (but relies on ICMP) traceroute - shows the route over the Internet to a given machine dnstracer (I think I got this via fink) - shows what DNS server is being used tcpflow (I got this via fink) - shows the contents of network packets being transmitted and received (easier to use than tcpdump which is already on your machine) Last edited by hayne; 05-16-2003 at 01:08 PM.

05-16-2003, 03:17 PM	#3
mervTormel League Commissioner Join Date: Jan 2002 Posts: 5,536	sounds like all your protocols that crap are HTTP, so i'd have a dig in that direction. HTTP proxy (privoxy) here swats iTMS, sherlock. not catastrophic, but just no results and no messages. __________________ On a clear disk, you can seek forever.

05-16-2003, 11:49 PM	#6
hayne Site Admin Join Date: Jan 2002 Location: Montreal Posts: 32,473	possibly related I recalled some discussion of an issue with certain web sites that resembled what you describe. I think this discussion at Macintouch of a problem with DNS and Akamai on 10.2.4 is what I was remembering: http://www.macintouch.com/mosxreader10.2pt59.html (search for AKamai - it's in a letter from Michael Rose)

05-16-2003, 04:02 PM	#4
aixccapt99 Major Leaguer Join Date: Feb 2003 Posts: 263	tcpflow is great--definitely recommended. That should let you see whether the http requests are ever going out or not, and if any reply is coming back. My other thought is some problem in the DNS lookups for these particular sites--is their DNS caching behaving strangely, or is lookup failing in a really bad way for these sites? I don't know enough about DNS to get into detail, but that would fit your diagnosis of a LAN-specific and www-site-specific but non-machine-specific problem. And you did say they run their own DNS... Don't know why bad DNS info could make iTunes/Sherlock crash, but maybe there is a bug in a code library they share (but Safari/IE don't use)? Let us know if you figure it out... Joe

05-16-2003, 04:28 PM	#5
yellow Moderator Join Date: Jan 2002 Posts: 10,677	I've seen similar discussions about browsers not being able to load sites properly. Apparently the naughty bunny was the router. The solution there was router firmware upgrades.