Hi,
This is mentioned in the perlfaq4 in the hashes part.
The quick answer is: you always have to iterate.
Please not that the username=>"Bob" part is a value of the primary hash.
Your hash looks like this:

%connections=( socket => { username => "Bob" } );
[download]

Where the value is therefore a reference to another hash.
So, your question is: how can I find the key when the value of a value is "Bob" and it's key is "username".
I hope this helps
---------------------------
Dr. Mark Ceulemans
Senior Consultant
IT Masters, Belgium