Network Security Engineer

On behalf of our client, a fast-growing company building a payment orchestration platform, we’re looking for a Network Security Engineer to design, secure and monitor the network behind it, including the segmented environment that handles cardholder data.

You’ll work closely with the platform and engineering teams to keep the network secure, well documented and easy to audit. This is a hands-on role: you’ll design segmentation and traffic controls, manage firewall and security group rules, build network monitoring and detection, and work with auditors and penetration testers to resolve findings.

What you'll do

• Design and maintain network segmentation in AWS, including isolation and scope reduction for the cardholder data environment.
• Define, review and maintain firewall, security group, network ACL and routing rules, with a documented justification for each.
• Secure connectivity to payment providers and merchants, including TLS, mutual TLS, private connectivity and IP allow-listing.
• Manage edge protection, including web application firewall, DDoS protection and rate limiting, and tune rules against real traffic.
• Build network monitoring and detection using flow logs, DNS logs and intrusion detection, and route alerts to the right people.
• Maintain accurate network and data-flow diagrams and evidence for PCI DSS assessments, including segmentation testing.
• Run regular rule reviews and vulnerability scans, and remove unused or overly permissive access.
• Define secure administrative access to production, with least privilege and strong authentication.
• Investigate network security events, take part in incident response and turn findings into improvements.
• Work with engineers, external auditors and penetration testers to resolve network security findings.

What we're looking for

• Experience as a network security engineer, or a network engineer with a strong security focus, in production environments.
• Strong understanding of TCP/IP, routing, DNS, TLS and common network attacks.
• Hands-on AWS networking experience, including VPC design, security groups, private connectivity and AWS WAF.
• Experience designing network segmentation and managing firewall rules in production.
• Experience with network monitoring, flow log analysis and intrusion detection.
• Experience managing infrastructure with AWS CDK or Terraform.
• Ability to write scripts that automate network and security tasks, for example in Python or TypeScript.
• Clear documentation habits and the ability to explain network risks to engineers and auditors.

Bonus points if you have experience with:

• PCI DSS, including segmentation testing, or another regulated environment.
• Payments or fintech.
• Mutual TLS and certificate lifecycle management.
• Security certifications such as AWS Certified Security – Specialty, CCNP Security or OSCP.

Why join

• An AI-first company: every team uses Claude and AI agents in their daily work, with training from day one
• Real ownership: join at the very beginning of a fast-growing payments company and help shape how we work from the ground up
• A friendly, ambitious team that moves quickly

What's in it for you

• Competitive salary, plus a discretionary annual performance bonus tied to agreed goals.
• 21 working days of paid annual leave
• Flexible working hours and a hybrid working model
• Birthday day off
• Private medical insurance from your first day
• Learning and development support