[AGENT++] USM user/username ?

[Jochen Katz]

Hi Karl,

> there are two different table for users and usernames in the USM, what are
> the difference ?

the next release will have these two comments for the classes ;-)

/**
  * This class holds USM users with PASSWORDS.
  *
  * Whenever the USM has to process a message of a user that is not
  * found in the USMUserTable, this table is queried for the
  * properties of the user. If the user is found, a localized entry
  * for the USMUserTable is created and used for processing the message.
  */
class USMUserNameTable : public SnmpSynchronized

/**
  * This class holds USM users with localized KEYS.
  */
class USMUserTable : public SnmpSynchronized

> And, what are the differences between add_usm_user with/without user_name ?

The funtion without username sets the username to the given securityname 
(which is recommended to avoid confusion). If you use the function with 
user_name, you can set the user_name to a different value.

 From USM RFC (2.1. User-based Security Model Users):

"   A user and its attributes are defined as follows:

    userName
       A string representing the name of the user.

    securityName
       A human-readable string representing the user in a format that is
       Security Model independent.  There is a one-to-one relationship
       between userName and securityName."

So the securityName is passed to the USM API and the SNMPv3 message that 
is sent contains the userName.

Regards,
   Jochen