[smokeping-users] best test to use?

[Adam Hardy]

I have a small LAN at home connected up to the net via a DSL modem on a gateway 
machine running lenny and iptables, and newly smokeping to monitor it all.

I have a problem with some software running on a windows machine on the LAN 
where the company who wrote the sofware say that there must be something wrong 
with my internet connection, but can't help any further.

I'd like to know what tests I can run to verify that my config and my firewall 
are OK, especially regarding PMTU.

I tried running without my firewall but it makes no difference so maybe it's 
something else out there with my ISP before it hits the public net.

What can I do with ping? This ping command gives suspicious results:

  ping -s 1473 mktgw1.ibllc.com

One byte less and it works. Fragmentation also works for normal websites like 
news.bbc.co.uk.

I'd massively appreciate any help with this! I'm stuck with either my own 
mistake, or until I can prove I haven't made one.

Thanks
Adam