With which service does PAM integrate for authentication in Linux?

PAM, or Pluggable Authentication Modules, integrates with several services for authentication in Linux, and one of the primary services is LDAP, which stands for Lightweight Directory Access Protocol. LDAP serves as a centralized directory service that can manage user identities and authentication data. When PAM is configured to use LDAP, it allows the system to authenticate users based on information stored in an LDAP directory. This integration is particularly useful in enterprise environments where user accounts and permissions need to be managed across multiple servers or applications.

While MySQL, SSH, and FTP are important in their respective roles within Linux systems, they do not serve as primary services for integrating PAM for authentication in the way LDAP does. MySQL is a database management system, SSH is a protocol for secure remote login, and FTP is an old protocol for file transfers, which do not inherently provide authentication mechanisms similar to those in LDAP. Therefore, the correct choice highlighting the service with which PAM integrates for authentication is LDAP.