login access to change account password only

["Robert Cates" <robert@kormar.de>]

Hi,

I would like to know how I can allow a customer to login to my server using
SSH (preferably using protocol 2 only) to only change the account password.
I know somebody who has an ISP who allows FTP access to update her web site,
and SSH access to change the account password.  That is, she connects with
SSH, she's asked for a (new) password, then she's immediately disconnected.
Or is it some other software on the ISP side authorizing access and it just
happens to be that she's using SSH to connect?

Thanks much for your help!
Robert