Is ssh abc@servername
different from ssh Abc@servername
? Does the case of the username matter in Unix?
My user authenticates via LDAP.
authenticationcase sensitivitylogin
Is ssh abc@servername
different from ssh Abc@servername
? Does the case of the username matter in Unix?
My user authenticates via LDAP.
Best Answer
Just like hostnames and domain names, the username is not strictly a Unix thing but can and often does span a wider range of OS types.
Whether they will be considered case sensitive depends then on the standard used to specify them.
Hostnames and domain names are clearly case insensitive by the DNS standard (see RFC4343).
Usernames stored on a local backend (/etc/passwd) or a Unix style one (NIS) are not case insensitive by the POSIX standard.
Usernames stored in an LDAP or an Active Directory backend will follow the used attribute schema definition,
uid
andcn
which are often storing the user name have a differing schema attributes, case insensitive for the former but case sensitive for the latter. That means bothAbc
andabc
might match or notabc
's entry depending on the ldap server configuration.Due to this inconsistency, I would recommend to only use lowercase for both usernames and host/domain name and then avoid
ssh ABC@SERVERNAME.DOMAIN.COM
which is rude anyway.