Senior Infrastructure Engineer (Linux Platforms)

Colt Technology Services; Greater London; On-site; GBP 90,000 - 120,000; Full time

Job summary

Colt Technology Services is seeking a Senior Infrastructure Engineer to own the design, implementation and lifecycle of Linux-based platforms supporting critical telecommunications services. You will drive automation, establish standards and provide leadership during major incidents.

The role covers DNS, routing control-plane services, authentication, identity management, observability and platform automation. Leadership and collaboration across engineering teams are essential.

Qualifications

• Extensive experience engineering enterprise Linux platforms (RHEL, Ubuntu).
• Deep Linux troubleshooting, lifecycle and platform design skills.
• Strong DNS design, delegation, resolution and governance.
• Solid TCP/IP, IPv4/IPv6, routing concepts (BGP), firewalls and load balancing.
• Knowledge of NTP, PKI, TLS, LDAP and identity management.
• Automation using Ansible, Bash or Python; IaC practices.
• Experience with HA, backup, DR, and continuity solutions.
• Familiarity with ISO 27001/CIS benchmarks and security controls.
• Experience leading complex incidents and RCA for cross-functional teams.
• Excellent communication with technical and non-technical stakeholders.

Responsibilities

• Act as technical authority for Linux platforms and services.
• Lead high/low-level designs for critical infrastructure changes.
• Create reusable engineering patterns and platform standards.
• Lead design reviews, risk assessments and migration planning.
• Mentor engineers and share knowledge across the team.
• Design and improve DNS, routing, auth and directory services.
• Collaborate with Network Engineering, Security, and Architecture teams.
• Define SLIs, health checks, monitoring and capacity metrics.
• Drive upgrades, migrations and platform currency improvements.
• Lead incident troubleshooting and root-cause analysis.

Skills

Linux platforms

DNS

TCP/IP

BGP

NTP

LDAP

Ansible

Python

Automation

High availability

Incident management

Security frameworks

Education

Degree in Computer Science or related

Tools

VMware

KVM

Docker

Podman

SAN/NAS

Azure

Google Cloud Platform

Job description

Why we need this role

The Senior Infrastructure Engineer is a technical authority responsible for the architecture, detailed design, implementation and lifecycle improvement of Linux-based platforms supporting critical telecommunications network services. The role leads complex engineering changes, establishes reusable standards, drives automation and provides technical leadership during major incidents and problem investigations.

Platforms and Services

• Authoritative, recursive and caching DNS services.
• Route reflectors and other routing control-plane services.
• Authentication, authorisation and accounting services.
• Identity management, directory and privileged-access integrations.
• Network observability, telemetry, logging and monitoring platforms.
• Network-management and automation services.
• Virtualised and, where appropriate, containerised infrastructure.
• Supporting services such as NTP, PKI, certificate management, secure repositories and configuration services.

What You Will Do

Technical Leadership and Platform Engineering

• Act as technical authority for assigned Linux platforms and services and provide advanced engineering guidance.
• Lead high-level and low-level designs for complex, critical or high-risk infrastructure changes.
• Set reusable engineering patterns, platform standards and implementation approaches.
• Lead technical design reviews, risk assessments, migration planning and operational acceptance.
• Mentor Engineers, review technical work and strengthen team capability through knowledge sharing.

Network-Critical Services

• Design, implement and improve enterprise DNS services, including architecture, delegation, resolution, resilience, security and troubleshooting.
• Engineer Linux platforms supporting route reflectors and other routing control-plane services in partnership with Network Engineering and Architecture.
• Design and enhance authentication, authorisation, accounting, identity and directory services, including Red Hat and Oracle LDAP environments.
• Engineer observability, monitoring, telemetry, logging and network-management platforms that support reliable network operations.

Resilience, Observability and Lifecycle

• Define service-level indicators, health checks, alerting strategies, logging standards, dashboards and capacity measures.
• Lead failure-mode analysis, resilience testing, failover exercises and backup and recovery validation.
• Plan and lead upgrades, migrations, platform currency improvements and decommissioning activities.
• Ensure monitoring, logging, security controls, backup and support documentation are included as part of every platform build.
• Lead complex incident troubleshooting and root-cause analysis and drive corrective and preventive actions.

Automation and Operational Excellence

• Design and maintain automation using Ansible, Bash, Python and infrastructure-as-code principles.
• Reduce manual effort, configuration inconsistency and operational risk through repeatable engineering patterns.
• Develop and maintain operating procedures for secure, stable and efficient platform management.
• Define implementation, testing, rollback and recovery approaches for significant engineering changes.

Security and Compliance

• Translate security and compliance requirements into platform designs, technical controls and validation criteria.
• Apply secure-by-design practices and contribute to threat modelling for critical network services.
• Engineer hardening, vulnerability remediation, privileged access, secrets, keys, certificates and centralised audit logging.
• Support security investigations and preserve relevant operational and forensic evidence.
• Identify and address risks associated with unsupported, end-of-life or non-compliant components.

Collaboration, Documentation and Support

• Work closely with Network Engineering, Security, Infrastructure, Architecture, Operations and application teams.
• Produce and maintain architecture documents, technical designs, implementation plans, support models, runbooks and audit evidence.
• Participate in the Infrastructure Operations on-call rota and provide senior technical leadership for priority incidents.

What We’re Looking For

Required Skills and Experience

• Extensive experience engineering enterprise Linux platforms using distributions such as RHEL and Ubuntu; experience with CentOS or successor-compatible distributions is beneficial.
• Deep Linux troubleshooting, performance, lifecycle and platform design capability.
• Strong DNS expertise, including design, delegation, resolution, resilience, security, troubleshooting and operational governance.
• Strong understanding of TCP/IP, IPv4 and IPv6, routing principles, BGP, network segmentation, firewalls and load balancing.
• Strong understanding of NTP, PKI, TLS, certificate lifecycle, authentication protocols, identity management and LDAP.
• Strong automation capability using Ansible, Bash or Python and infrastructure-as-code principles.
• Experience designing and validating high-availability, backup, restoration, continuity and disaster-recovery solutions.
• Deep understanding of security frameworks and standards such as ISO 27001 and CIS benchmarks.
• Experience leading complex technical incidents, root-cause analysis and cross-functional engineering delivery.
• Excellent communication skills for technical and non-technical stakeholders.

Desirable Skills And Knowledge

• Advanced knowledge in one or more of routing infrastructure, AAA, identity, network observability or network monitoring.
• Virtualisation platforms such as VMware and KVM.
• Containerisation technologies such as Docker or Podman and awareness of Kubernetes operational workflows.
• Enterprise storage technologies such as SAN and NAS.
• Oracle databases and their integration with Linux.
• Windows Server environments.
• On-premises and cloud environments including Microsoft Azure and Google Cloud Platform.

Leadership and Behaviours

• Ownership and accountability: takes responsibility for high-quality technical and service outcomes.
• Technical leadership: guides engineering activity and decisions without formal line management.
• Outcome-driven: focuses on measurable, reliable, resilient and secure results.
• Strategic thinking: aligns technical decisions with broader network and business strategy.
• Communication: presents complex technical decisions clearly to technical and non-technical stakeholders.
• Collaboration: builds strong working relationships across network engineering, architecture, security, infrastructure and operations.
• Adaptability and continuous improvement: responds effectively to operational change and identifies opportunities for optimisation and innovation.

Preferred Qualifications / Education And Experience

• Degree in Computer Science, Network Engineering or a related discipline, or equivalent relevant industry experience.
• Typically seven or more years of relevant Linux or infrastructure engineering experience.
• Certifications such as RHCE, LFCS, LFCE or relevant network or security credentials are beneficial.

Summary

Senior technical authority role focused on the design, delivery, lifecycle, resilience, security and operational excellence of Linux-based platforms supporting critical telecommunications network services.