Zimbra & Network Infrastructure Engineer (Sahibabad)

Experience: 35 years Employment Type: Full-time Location: Sahibabad Reports To: Engineering Manager / CTO About the Role We run a Zimbra Collaboration Suite (FOSS) deployment integrated with an in-house Document & Data Management System (DDMS) through single sign-on, zimlets, and a reverse-proxied service mesh. We are looking for an infrastructure specialist to own the Zimbra platform, the SSO layer (Keycloak), and the surrounding network plumbing DNS, TLS, reverse proxy, and Docker services. You will work alongside a separate application development team: they build the zimlets and DDMS application; you make the platform they run on reliable, secure, and reproducible. Key Responsibilities Administer Zimbra 10.x (FOSS): mailboxd, zmprov, zmcontrol, domain configuration, preauth keys, virtual/public service hostnames, class-of-service, and account provisioning. Deploy and manage zimlets delivered by the development team zmzimletctl deployment, cache flushes, service restarts, and post-deploy health verification. Own the SSO layer: Keycloak realm and client administration, OIDC configuration, group and role management, LDAP user federation against Zimbra's directory, and Zimbra preauth-based seamless login. Manage the network path end to end: internal DNS / hosts resolution, TLS certificates and private CA trust, Caddy (or Nginx) reverse proxy configuration, CORS and Content-Security-Policy headers for cross-origin iframe embedding. Operate the supporting Docker Compose stack Keycloak, PostgreSQL, MongoDB, Collabora Online including upgrades, volumes/backups, and container networking (host-gateway, port mappings). Administer Linux VMs: SSH key lifecycle and hardening, sudoers policy for delegated commands, firewall/port management, service monitoring, and log analysis (mailbox.log, proxy and container logs). Automate operations with Bash and PowerShell deployment scripts, environment resets, smoke tests and keep runbooks and integration documentation current. Manage mail flow and deliverability: SMTP relay configuration, DNS records (MX, SPF, DKIM, DMARC), and troubleshooting message delivery issues. Diagnose issues across the full chain browser, proxy, Keycloak, Zimbra including certificate errors, token/preauth failures, redirect loops, and WOPI callback connectivity. Required Skills & Experience 3+ years in Linux system administration, with at least 2 years administering a production mail platform Zimbra strongly preferred (Postfix/Exchange/Carbonio considered). Working knowledge of Zimbra internals: zmprov, zimlet deployment, preauth, LDAP directory, proxy/mailbox architecture. Strong networking fundamentals: TCP/IP, DNS, TLS/PKI (including private CAs), reverse proxies, NAT/firewalls. Hands-on Keycloak (or comparable IdP) administration and solid understanding of OIDC, SAML, and LDAP federation. Docker and Docker Compose in production or lab operations. Confident scripting in Bash; PowerShell experience for Windows-side automation. SSH-based remote administration, key management, and security hardening on Ubuntu/RHEL-family servers. Clear documentation habits runbooks, checklists, and reproducible environment builds. Nice to Have Zimbra certification or experience with Zimbra upgrades, migrations, and backup/restore. Collabora Online / LibreOffice Online deployment or WOPI protocol exposure. Experience supporting SSO integrations for web applications (redirect flows, cookies, CSP/iframe constraints). Virtualization platforms (VMware, Proxmox, Hyper-V) and Windows/WSL2 environments. Monitoring and alerting (Zabbix, Prometheus/Grafana) for mail and proxy services. What Success Looks Like The entire lab Zimbra, Keycloak, proxy, Docker services can be rebuilt from your documentation on a fresh machine in under a day. A Zimbra user reaches DDMS through SSO with zero certificate warnings and zero password prompts, and you can explain every hop in that flow. Zimlet and configuration rollouts are scripted, smoke-tested, and repeatable by anyone on the team. How to Apply Send your CV and a short note on a Zimbra (or comparable mail platform) workplace you have administered scale, SSO setup, and one hard problem you solved to []. Compensation: 50,000.00 - 100,000.00 per month Work Location: In person .