Here's a select statement to find out the Users connected in all clients:
select AH_oh_idnr, oh_name, AH_HostDst,AH_timestamp1, AH_idnr from AH, OH where AH_OH_Idnr=OH_Idnr AND AH_OType='USER' AND AH_SType='DIALOG' AND AH_TimeStamp4 is NULL;
It'll return the User ID, Username, where they are connecting from, when they first connected and the session id.