How to Capture the user IP

Does any one knows how to capture the user IP within a trigger?

I know how to capture the hostname etc. but I'd like to capture the IP from the user who is doing the UPDATE,DELETE,INSERT to the table that has the trigger.

Explain I have web application that update such table and there is another third party application that insert into the table also table can be updateable via the SQL query analyser
the trigger I have now works fine capturing the hostname, appname date/time etc but instead reading the audit log table which where the trigger logs the update,insert of the master table that has the trigger the application name which only gives me internet information service when done via the internet or SQL Query Analyser when is done via de Query Analyser I'd like to read the IP of the user who actually did the update.

Is the Above possible, without using web scripting?

Please forgive me if above explanation is not well explained.

TIA