User IDs

If the IBM® WebSphere® MQ MQI client is on Windows and the IBM WebSphere MQ server is also on Windows and has access to the domain on which the client user ID is defined, IBM WebSphere MQ supports user IDs of up to 20 characters. On UNIX and Linux® platforms and configurations, the maximum length is 12 characters.

A WebSphere MQ for Windows server does not support the connection of a Windows client if the client is running under a user ID that contains the @ character, for example, abc@d. The return code to the MQCONN call at the client is MQRC_NOT_AUTHORIZED.

However, you can specify the user ID using two @ characters, for example, abc@@d. Using the id@domain format is the preferred practice, to ensure that the user ID is resolved in the correct domain consistently; thus abc@@d@domain.

Note that UNKNOWN is a reserved user ID and the NOBODY user ID also have special meanings to WebSphere MQ. Creating user IDs in the operating system called UNKNOWN or NOBODY could have unintended results.

Although user IDs are used to authenticate, groups are used for authorization, except for Windows.

If you create service accounts, without paying attention to groups, and authorize all the user IDs differently, every user can access the information of every other user.