UDP not connecting on Mac OSX Leopard - solved

[Jim Ault]

UDP *does indeed* work as expected on Mac OSX 10.5

My client situation was complicated by the un-manned data center  
configuration of multiple firewalls, multiple Mac mini computers and a  
few settings that were incorrect.

I did not have admin access to the physical firewalls and these  
settings caused a few errors that were hard to trace.
Added to this was a few special filters I programmed in to the test  
loops for the UDP Echo Client and Echo Server.
The tracing steps made assumptions that later became known to be false.
After the technician in the data center set all ports correctly, every  
test became valid.

Most all testing was done on remote computers
TCP always worked.
UDP only worked in a few cases.
The test software was not reset to the default (my error) and added  
more dis-information to the mix.

I will report back in a week or so to confirm success for all  
combinations of ...
TCP  and UDP ...
Rev  2.7.2   2.9.0   and   3.5   running on ...
Mac OSX 10.5  +  Win Server 2003  +  XP Pro + XP Home Edition ...
both remote and local

I will leave the Win ME testing to those who enjoy leaping off of tall  
structures with minimal padding.

Thanks to Alex Tweedly and Jim Sims for help and support.
(Jim Sims spoke with me using Skype and tried to help with Rev 3.5,  
very cool)
I will even try a little packet-speed testing between Las Vegas and  
Malta, if Jim has the time.

It feels really good to have the speed of UDP as part of my tool box  
again !!
Jim Ault
Las Vegas


On Jul 7, 2009, at 5:05 PM, Alex Tweedly wrote:

> Jim Ault wrote:
>
> Jim - I could preface each part of my reply with .... "Sorry I don't  
> have a Mac w/ Leopard to check,"
>> I don't seem to be able to make the easy connections between Macs  
>> running OSX 10.5 using Alex Tweedly's companion stacks
>> UDP Echo Client
>> UDP Echo Server
>>
>> I have set the fire wall in OSX to 'allow all incoming connections',
> ...check, but I wouldn't be surprised if that meant "allow incoming  
> TCP connections", and there might be a separate setting for UDP.
>> both computers have a static IP address,
>> are connected to the internet using a switch (not a router)
>>
> No, I don't believe that. (Almost) no-one is connected to the  
> Internet without a router - it's just a question of where the router  
> is. Do you mean that the computers are both connected to a switch -  
> and behind that is the router and Internet connection ? And  
> therefore the two should be communicating locally ?
>> but UDP traffic between them does not test positive.
>> This has not been a problem in the past using OSX 10.4 (Tiger)
>>
>> [1]
>> compiled - UDP Echo Client running as an app on computer B
>> UDP Echo Server in Rev 2.7.2 on computer A
>>
>> [2]
>> compiled - UDP Echo Client running as an app on computer B
>> UDP Echo Server in Rev 2.9.0 on computer A
>>
> Do you still have 10.4 systems around so you can try client on 10.4  
> and server on 10.5, etc. ?
>> Can anyone shed some light on how to make this work?
> Stupid question - does it work with client and server on the same  
> computer ?
> Are they on the same subnet ?
> Can you do a ping from one to the other ?
> How about a traceroute - just to check there is a direct connection ?
> If you clear the arp cache, then run the client, does the sever then  
> show up in the arp cache ?
>  (in a terminal window - "arp -a" to see the cache, "arp -d -a" to  
> clear it)
>
>
> I'll try to find a Leopard system tomorrow to play with it ....

Jim Ault
jimaultwins at yahoo.com