System Administration Guides and Best Practices

Configure OpenLDAP sudoRole policies with SSSD on RHEL, Rocky Linux, AlmaLinux, Oracle Linux, and CentOS Stream clients.

Fix OpenLDAP Error 49 for wrong bind DNs, passwords, userPassword ACLs, locked accounts, expired passwords, SSSD cache, PAM, and SSH authentication.

Configure OpenLDAP memberOf and refint overlays for groupOfNames membership, reverse membership lookup, and automatic reference cleanup.

Fix OpenLDAP Error 50 for ldapadd, ldapmodify, ldapdelete, password changes, cn=config, and no-write-access-to-parent ACL failures.

Configure OpenLDAP ppolicy for password expiration, warnings, history, account lockout, grace logins, forced resets, and SSSD client behavior.

Back up and restore OpenLDAP cn=config and all MDB databases using slapcat, slapadd, systemd timers, retention, checksums, and tested recovery.

Configure OpenLDAP olcAccess ACLs for passwords, users, groups, SSSD, entry and children permissions, with safe testing and rollback.

Understand OpenLDAP cn=config and MDB, discover numbered database DNs, query modules and overlays, and safely modify settings with ldapmodify.

Add, search, modify, rename, reset passwords, manage group membership, and delete OpenLDAP POSIX users and groups using LDIF.

Configure OpenLDAP client authentication with SSSD, authselect, StartTLS, and automatic home directories on RHEL, Rocky Linux, AlmaLinux, Oracle Linux, and CentOS Stream.

OpenLDAP vs Active Directory in plain language: LDAP protocol vs directory services, OpenLDAP vs LDAPS, Samba AD vs Microsoft AD, cost, GPO, Kerberos, Linux integration, and when to choose each.

In this tutorial we will cover the steps to install and configure OpenLDAP from scratch and then use the OpenLDAP server as a central authentication server

OpenLDAP is an open-source implementation of the Lightweight Directory Access Protocol (LDAP). It's widely used for managing directory information, providing

Migrate OpenLDAP configuration, schemas, directory data, TLS files, and client endpoints to a new RHEL, Rocky Linux, AlmaLinux, Oracle Linux, or CentOS Stream server.

Configure OpenLDAP multi-provider or multi-master replication with server IDs, accesslog, delta-syncrepl, StartTLS, MirrorMode, and conflict testing on RHEL-family Linux.

Configure one-way OpenLDAP provider-consumer replication with Syncrepl and StartTLS on RHEL-based Linux, including Rocky and AlmaLinux.

Configure OpenLDAP TLS on RHEL, Rocky Linux, AlmaLinux, Oracle Linux, and CentOS Stream using a private CA, StartTLS, LDAPS, and cn=config.

Install OpenLDAP 2.6 on RHEL-based Linux, configure MDB with cn=config, create the base DIT, and verify local and remote LDAP searches.

Configure OpenLDAP with TLS certificates on Ubuntu . Secure LDAP connections with TLS/SSL. Create our own CA and sign our certificate to use it with LDAP.

Learn the steps to install and configure OpenLDAP on Linux using ldapmodify and cn=config database. Add and delete user, group, objects from ldap database

Learn LDAP and OpenLDAP basics, including entries, attributes, DN, RDN, DIT, schemas, object classes, LDAP operations, slapd, cn=config and the MDB backend.

Configure Apache HTTP Server to authenticate and authorize users with OpenLDAP using mod_authnz_ldap, group restrictions, TLS, and practical troubleshooting.

Fix missing Bash history commands in Linux, including commands lost across multiple terminals, delayed .bash_history writes, HISTCONTROL exclusions, and permission problems.

Free, hands-on OpenLDAP tutorial for the RHEL family — install on Rocky, AlmaLinux, and RHEL, operate cn=config and MDB, index searches, manage POSIX users and groups, configure TLS and ACLs, integrate SSSD clients with …

Understand TTY, PTY and PTS in Linux, including /dev/tty, /dev/pts, controlling terminals, terminal emulators, SSH, tmux, and practical commands.

Configure OpenLDAP users with NFS home directories using SSSD and autofs on RHEL, Rocky Linux, AlmaLinux, Oracle Linux, and CentOS Stream.

Check, disable or set Transparent HugePages to madvise on RHEL 8–10, Rocky Linux, AlmaLinux, CentOS Stream and Oracle Linux.

Download and sync complete RPM repositories on RHEL 8/9/10, Rocky Linux, AlmaLinux, CentOS Stream, and Oracle Linux using dnf reposync, repository metadata, GPG verification, and offline clients.

Configure Postfix as a null client or internal SMTP relay on RHEL 9 and 10, Rocky Linux, AlmaLinux, CentOS Stream, and Oracle Linux using relayhost, SASL authentication, STARTTLS, SWAKS, and queue troubleshooting.

Create a system-level systemd service that starts at boot and runs as a dedicated non-root user and group on Ubuntu, Debian, Fedora, RHEL, Rocky Linux, AlmaLinux, CentOS Stream and Oracle Linux.