Python Backend Developer (Regular)

Quick Facts

• Role: Python Backend Developer (Regular)

• Focus: Network authentication (MFA) and security log delivery to SIEM

• Work mode: Fully on-site in Kraków or Zielona Góra, or fully remote from anywhere in Poland (B2B)

• Language: Polish for everyday team communication; English for reading technical documentation/RFCs

Description

You will develop backend products that add MFA and security monitoring to enterprise networks. Work on a RADIUS/LDAP Authentication Proxy and on a log export service that sends audit/auth/activity logs to SIEM systems in JSON or CEF. Reliability, performance, and secure handling of network protocols at scale are core expectations.

Responsibilities

• Develop and maintain the Authentication Proxy and Log Sync services.

• Implement RADIUS and LDAP protocol features: authentication modes, proxying, and RadSec.

• Build integrations with Active Directory, OpenLDAP, FreeIPA, Google Secure LDAP, Microsoft Entra ID, and existing RADIUS servers.

• Develop Directory Sync to synchronize users and groups from directories into Rublon MFA.

• Deliver SIEM logs reliably (checkpoints, retries) using correct CEF, syslog, and JSON formats.

• Harden network service security: TLS/mTLS, certificate verification, secrets handling, and protection against threats like Blast-RADIUS.

• Improve performance, concurrency, and resource usage for high-volume authentication and logging.

• Enhance observability with structured logging, metrics, and diagnostics.

• Build and maintain Linux (systemd) and Windows Server packages/installers.

• Test integrations with VPNs, firewalls, directory services, and SIEM platforms.

• Implement features within the agreed architecture and propose improvements.

• Use AI coding agents (e.g., Claude Code) daily and critically validate outputs.

• Participate in code review and share knowledge with the team.

• Collaborate with product managers, QA, support, and cybersecurity specialists.

Requirements

• Minimum 3 years of commercial Python backend development.

• Strong networking fundamentals: TCP/IP, UDP, DNS, and TLS.

• Practical protocol-level knowledge of RADIUS or LDAP (not just configuration).

• Experience with Active Directory or other LDAP directory systems.

• Concurrency experience in Python (asyncio, threads, or processes).

• Secure coding principles for network services, including handling untrusted input and secrets.

• Experience running and debugging services on Linux.

• Automated testing and CI/CD experience (preferably GitHub pipelines).

• Practical experience building software using AI tools (e.g., Claude Code).

• Ability to work independently and clearly justify technical decisions.

• Polish proficiency at C1.

• English proficiency at B1 for reading technical documentation and RFCs.

Benefits

• Private medical care.

• MultiSport card.

• Access to online courses and the option to co-fund certifications.