Firewall Engineer

Role Title: Firewall Engineer
Location: Sheffield (3 days onsite is mandatory)
Duration: November 2026
Rate: £435p/d via Umbrella

Overview

We are seeking an experienced Firewall Engineer to join the Firewall Engineering team, responsible for designing, implementing, and supporting enterprise network security solutions. The role requires strong hands on expertise with Fortinet and Juniper Firewalls and the ability to operate at Level 3 (L3) support within a complex enterprise environment.

Key Responsibilities

• Design, implement, and support Fortinet and Juniper Firewall platforms.
• Provide L3 support for Firewall related incidents, problems, and complex service requests.
• Troubleshoot advanced network and security issues across enterprise environments.
• Manage Firewall rulebases, NAT policies, security zones, and objects in line with security standards.
• Support Firewall changes, upgrades, patching, and migrations.
• Perform root cause analysis and drive permanent fixes for recurring issues.
• Collaborate with network, security, and infrastructure teams to ensure secure connectivity.
• Ensure compliance with internal security policies and regulatory requirements.
• Maintain accurate documentation, configurations, and operational procedures.
• Participate in on call rotas and provide out of hours and weekend support when required to support business critical services and incident resolution.

Required Skills & Experience

• Minimum 5 years of hands on experience in Firewall engineering or network security roles.
• Strong expertise in Fortinet (FortiGate) and Juniper (SRX) technologies.
• Solid understanding of L3/L4 networking concepts, routing, and traffic flow.
• Proven experience providing L3 operational support in production environments.
• Strong troubleshooting and analytical skills.
• Ability to work effectively under pressure, including during major incidents.

Desirable

• Experience working in regulated or enterprise environments (eg banking or financial services).
• Exposure to high availability designs, VPN technologies, and security best practices.
• Relevant vendor certifications (eg Fortinet NSE, Juniper JNCIA/JNCIS).