Job Overview:We are seeking an accomplished and technically astute Level 3 Linux System Administrator to join our high-performance infrastructure team. This individual will serve as a subject matter expert (SME) on Linux systems, providing deep operational insight, advanced troubleshooting, performance tuning and capacity planning. Demonstrate a strong balance on hands-on expertise, automation mindset, and a strategic approach to system scalability, security, and lifecycle management.Responsibilities:<ul><li>Deliver expert-level support and resolution for complex incidents and problems within the Linux ecosystem, ensuring minimal business impact and adherence to SLAs.</li><li>Troubleshoot and resolve escalated issues in the Linux Environment.</li><li>Proactively monitor system health, performance and capacity to ensure stability, availability and reliability.</li><li>Perform Kernel Upgrade, patches and Vulnerability Management to ensure compliance meeting the organization standards.</li><li>Design and enforce system hardening, access control, and security baselines aligned with the compliance framework.</li><li>Server as escalation point and technical advisor for Level 1 and 2 administrators, develop technical runbooks and knowledge-based articles.</li><li>Participate and lead initiatives for architectural reviews, infrastructure modernization, and enterprise risk assessments.</li><li>Lead Major Incidents and engage with stake holders to perform Root Cause Analysis and provide permanent solutions.</li></ul> Skills &amp; Qualifications <ul><li>8+ years of progressive experience in Linux Server Administration with enterprise level skills in Physical and virtual environment management.</li><li>Deep Understanding of Linux security methodologies, Hardening procedure and best practices.</li><li>Deep Understanding of Linux Internals – Process Management, Memory handling. Kernel Tuning, Capacity planning.</li><li>Evaluate and maintain server storage and other IT standards for the enterprise and all supporting products and services.</li><li>Hands on Experience with automation tools (Ansible, Chef, Puppet)</li><li>Analyze server and storage characteristics (e.g., CPU behavior latency transmission speeds packet loss and throughput) triage and troubleshoot problems. Knowledge and experience of Root Cause Analysis (RCA) required</li><li>Familiarity with complex multi-site and global network design multi-layered switch environment firewalls VPN Load balancers and DNS</li><li>Familiar with the fundamentals of web application and relational database architectures</li><li>Knowledge and writing a code and script (Shell, Python. Perl, Yaml, and / or PHP) is a huge plus.</li><li>Knowledge with analytics and observability tools (Grafana, Kibana, Elk, Splunk, AppDynamics) is a plus</li><li>Experience with container technologies (docker, Kubernetes, openShift, AWS, GCP).</li></ul>​ Education:<ul><li>Bachelors/University degree in Computer Science/Engineering preferred or equivalent experience</li></ul>------------------------------------------------------Job Family Group: Technology------------------------------------------------------Job Family:Infrastructure------------------------------------------------------Time Type:Full time------------------------------------------------------Primary Location:Irving Texas United States------------------------------------------------------Primary Location Full Time Salary Range:$125,760.00 - $188,640.00 In addition to salary, Citi’s offerings may also include, for eligible employees, discretionary and formulaic incentive and retention awards. Citi offers competitive employee benefits, including: medical, dental &amp; vision coverage; 401(k); life, accident, and disability insurance; and wellness programs. Citi also offers paid time off packages, including planned time off (vacation), unplanned time off (sick leave), and paid holidays. For additional information regarding Citi employee benefits, please visit citibenefits.com. Available offerings may vary by jurisdiction, job level, and date of hire.------------------------------------------------------Most Relevant Skills Please see the requirements listed above.------------------------------------------------------Other Relevant Skills Kubernetes, Linux Programming, Linux Server Administration, Linux System Administration, Linux Systems Programming, Python (Programming Language), Red Hat Ansible, Red Hat OpenShift.------------------------------------------------------Anticipated Posting Close Date:Sep 29, 2025------------------------------------------------------Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law. If you are a person with a disability and need a reasonable accommodation to use our search tools and/or apply for a career opportunity review <a href="https://www.citigroup.com/citi/accessibility/application-accessibility.htm" target="_blank">Accessibility at Citi</a>. View Citi’s <a href="https://www.citigroup.com/global/eeo-aa-policy" target="_blank">EEO Policy Statement</a> and the <a href="https://www.eeoc.gov/sites/default/files/2023-06/22-088_EEOC_KnowYourRights6.12ScreenRdr.pdf" target="_blank">Know Your Rights</a> poster.