Senior Systems Administrator

The Ideal Candidate

You thrive in an environment of organised chaos. You can hold ownership of long‑running infrastructure projects, while also dropping everything to troubleshoot urgent network, system or application issues.

You are comfortable following strict procedures where required, and applying pragmatic judgement and creative problem solving when needed. You approach gaps in your knowledge with an “I don’t know yet” mindset, and you enjoy sharing knowledge and teaching skilled colleagues new approaches.

The Role

As a Senior Systems Administrator, you will be part of a small, highly capable team responsible for building and maintaining Entersekt’s infrastructure, deploying applications, and managing the databases and services that support them.

Your primary focus will be on network and datacentre operations. As these activities typically require only part of your time, you will also take on a broad range of systems administration responsibilities and provide support to internal teams and customers. This is a senior, hands‑on individual contributor role in a security‑critical environment.

Responsibilities

• Build, operate and maintain secure, scalable systems within Entersekt’s physical datacentres.
• Operate, maintain and monitor Java‑based application platforms across production and non‑production environments.
• Operate, maintain and troubleshoot a FreeBSD‑based server platform, ensuring availability, performance and security.
• Design, operate and maintain network and systems infrastructure, including both FreeBSD‑based and commercial (“off‑the‑shelf”) components.
• Manage, maintain and improve routing and network infrastructure, both internally and externally.
• Install, maintain and troubleshoot hardware in Entersekt datacentres and shared facilities.
• Support the operation and hardware maintenance of PCI‑regulated infrastructure within shared datacentre environments.
• Operate and support network resilience and availability services, including response to large‑scale traffic or availability incidents.
• Assist internal security teams with vulnerability scanning, penetration testing and other security and compliance‑related activities.
• Improve configuration management, package building and deployment mechanisms.
• Handle change requests, deployments and routine operational tasks across the business.
• Participate in change management planning, implementation and post‑change reviews, in line with internal controls and operational procedures.

Skills and Experience

Successful candidates for this role will generally possess the following qualifications and skills:

• 6+ years of experience in a Systems Administrator, Infrastructure Engineer or Network Administrator role.
• Strong network management skills, including maintaining, developing and troubleshooting complex network architectures.
• Hands‑on experience with BGP and OSPF routing, GRE tunnels, IPSec and WireGuard VPNs, and FreeBSD‑based open-source firewall platforms.
• Strong troubleshooting capability, including packet capture analysis using tools such as Wireshark or termshark.
• Solid experience working in on‑prem or hybrid datacentre environments.
• Technical environment and domain experience (strongly preferred):
  • FreeBSD as a primary operating system.
  • MariaDB as a database engine, including experience with Galera clusters.
  • Extensive use of ZFS and FreeBSD jails.
  • Experience with network security scanning and related tooling.
  • Familiarity with Tomcat and Java servlet environments.
  • Fundamental understanding of security concepts, with a strong interest in secure system design.
  • Practical understanding of cryptography concepts, including correct and incorrect usage.

Personality Attributes

• Calm and decisive problem solver who handles urgent issues with composure.
• Curious and growth oriented, with a willingness to learn and share knowledge.
• Ownership driven, with a strong security first mindset.
• Comfortable working autonomously while collaborating closely with skilled peers.