Network Security Engineer

Cloudflare

. Support Cloudflare’s largest and most technically sophisticated customers with technical problems, threats, and attacks across OSI Layers 3, 4, and 7 .

Posted 10/27/2026full-timeLisbon • PortugalMid-LevelSenior💰 €38,000 - €52,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expertise in troubleshooting network connectivity issues and mitigating attacks across OSI Layers 3, 4, and 7. Proficient in using command-line tools and scripting languages to analyze traffic and improve customer solutions.

Highest-signal resume keywords

OSI Model UnderstandingTCP And UDP ProficiencyPacket Capture AnalysisCommand-Line Tools ExperienceWeb Server Configuration

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Network Connectivity TroubleshootingBGP RoutingGRE TunnelsScripting In BashScripting In PythonScripting In JavaScriptPacket InspectionTraffic Signature ComparisonDatabase ExperienceWeb Development Experience

Soft Skills

Customer-Facing Role ExperienceAbility To Learn New Technologies

Tools & Technologies

IptablesLooking GlassCurlDigTracerouteOpensslGitApacheNginxCaddy

Industry Keywords

CloudflareMalicious Traffic FilteringMagic TransitNetwork FirewallWAFIP Reputation ListsBlocklistingAllowlistingRate LimitingPacket Inspection

Tech Stack

Tools & technologies

ApacheDNSJavaScriptMySQLNGINXPostgresPythonSQL

About the role

Key responsibilities & impact

Support Cloudflare’s largest and most technically sophisticated customers with technical problems, threats, and attacks across OSI Layers 3, 4, and 7
Communicate with customers via chat, email, and phone
Compare traffic signatures and attributes, including IP addresses, cookie variations, HTTP headers, and JavaScript footprints, to distinguish legitimate from malicious traffic
Advise customers on filtering malicious traffic using Magic Transit, Network Firewall, WAF, IP reputation lists, packet inspection, blocklisting, allowlisting, and rate limiting
Work with Engineering and Operations teams to mitigate attacks, recommend mitigation steps, and apply appropriate mitigations
Work with Engineering and Product teams to improve products and tools

Requirements

What you’ll need

Fundamental understanding of how the Internet works (OSI Model)
Advanced understanding of TCP and UDP
Computer networking fundamentals
Experience with iptables and looking glass
Experience troubleshooting network connectivity issues, BGP routing, and GRE tunnels
Packet capture analysis
Experience with command-line tools including curl, dig, traceroute, openssl, and git
Experience troubleshooting DNS, SSL/TLS, and HTTP
Experience in a web development and/or hosting environment
Experience installing and configuring web servers such as Apache, Nginx, Caddy, and IIS
Experience writing scripts in Bash, Python, JavaScript, or another scripting language
Experience working as part of a team in a customer-facing role
Ability to learn new technologies, systems, and features with little guidance
Fluency in German, Japanese, French, Spanish, Portuguese, or Mandarin is a bonus
Experience with PostgreSQL, MySQL, MS SQL, or other database servers is a bonus
Familiarity with Cloudflare and active use of its platform is a bonus
Authorization to receive software or technology controlled under U.S. export laws without sponsorship for an export license may be required

Benefits

Comp & perks

Equity plan participation
Opportunity to attend an in-person interview within a Cloudflare office or hub at the offer stage