[Hiring] Lead Unix/Linux Security Engineer @S3

Role Description

Our client is seeking a Lead Unix/Linux Security Engineer to support and enhance enterprise Linux authentication, identity integration, and operating system security across a large-scale environment. This hands-on engineering role is responsible for configuring, troubleshooting, and maintaining secure authentication services while partnering with infrastructure, security, and networking teams to ensure secure and reliable access to critical systems.

• Configure, maintain, and troubleshoot enterprise Linux authentication services using SSSD.
• Integrate Linux systems with Active Directory, LDAP, and Kerberos.
• Diagnose and resolve authentication failures, SSSD caching issues, domain join problems, and cross-realm trust issues.
• Configure and maintain Linux PAM stack and sudo policies.
• Implement Linux security hardening and secure access best practices.
• Coordinate with firewall and network teams to establish secure communication between Unix/Linux servers.
• Create, modify, and manage Linux groups and permissions supporting enterprise applications.
• Troubleshoot production issues related to password expiration, access permissions, group privileges, and authentication.
• Support endpoint privileged management solutions and enterprise identity integrations.
• Develop and maintain automation using Bash, Python, Ansible, or Puppet.
• Participate in production change windows outside of normal business hours as needed.

Qualifications

• 8+ years of experience as a Unix/Linux Systems Engineer, Linux Security Engineer, or similar role.
• Strong hands-on experience with System Security Services Daemon (SSSD).
• Experience configuring and supporting:
  • Kerberos
  • LDAP
  • Active Directory integration
• Advanced experience administering:
  • Red Hat Enterprise Linux (RHEL)
  • CentOS
  • Ubuntu
• Strong knowledge of:
  • Linux authentication
  • PAM configuration
  • sudo policy management
  • Enterprise identity management
• Experience troubleshooting:
  • Authentication failures
  • Password expiration
  • SSSD caching
  • Domain joins
  • Cross-realm trust issues
• Experience implementing Linux hardening and secure access models.
• Experience coordinating with firewall teams on secure Linux communications.
• Automation experience using Bash, Python, Ansible, or Puppet.

Preferred Qualifications

• Experience supporting large enterprise Linux environments.
• Background in the financial services or insurance industry.
• Familiarity with Endpoint Privileged Management (EPM) solutions.

Top Skills

• SSSD (System Security Services Daemon) – Expert-level experience
• Kerberos, LDAP, and Active Directory Integration – Advanced experience
• Enterprise Linux Administration (RHEL/CentOS/Ubuntu) – Advanced experience