RADIUS Attribute - User Name

As per RFC 2865

This Attribute indicates the name of the user to be authenticated. It MUST be sent in Access-Request packets if available. It MAY be sent in an Access-Accept packet, in which case the client SHOULD use the name returned in the Access-Accept packet in all Accounting-Request packets for this session.  If the Access-Accept includes Service-Type = Rlogin and the User-Name attribute, a NAS MAY use the returned User-Name when performing the Rlogin function. A summary of the User-Name Attribute format is shown below. The fields are transmitted from left to right.

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