• UserDatabase
• NSS

NSS

(v1.1+ only)

Usually NSS is used with passwd userdb, but it has one problem: It can't distinguish between temporary and permanent errors. So if you're using e.g. nss_ldap and your LDAP database is down, all userdb lookups may return "user doesn't exist" errors. This is especially bad if you're using deliver, which causes the mails to be bounced back to sender.

The NSS userdb works around this problem by loading the NSS modules and calling them itself. This is a bit kludgy, and it probably works only with Linux.

This userdb has two parameters:

• service=<name>: This parameter is required. The name specifies what NSS module to use, for example "ldap".

• blocking=yes causes the lookups to be done in worker processes. You'll probably want to use this with LDAP/SQL/etc. remote database lookups.

Example

userdb nss {
  args = service=ldap blocking=yes
}