Theerendra Kumar Kumar

Network & Security Engineer

Madras Networking Private Limited

Oct 2024 - Present

Supported enterprise network operations across switching, routing, firewall security, VPN and endpoint security, handling connectivity issues from access-layer devices through the security perimeter. Configured Cisco and Aruba switches with VLANs, access/trunk ports, STP/RSTP, EtherChannel/LACP and uplink connectivity; performed port-level troubleshooting and switch configuration validation during deployments and changes. Worked with OSPF and static routing, DHCP and DNS services, including troubleshooting of route selection, IP allocation and name-resolution issues affecting users and applications. Staged and commissioned Check Point Security Gateways and Smart-1 Management Server, including interface/IP addressing, hostname, gateway, DNS, management and logging configuration. Executed firewall migration activities using backup/restore of policies, NAT, VPNs, network objects, service objects and users; supported lab validation, production cutover and post-change traffic checks. Configured ClusterXL Load Sharing with two active members and supported high-availability validation, including traffic distribution and failover testing. Configured ISP redundancy/load sharing using link weights and ICMP-based monitoring; troubleshot internet-access issues by reviewing route priorities and traffic paths. Implemented and maintained Check Point access-control policies, network/host/service/group objects, manual and automatic NAT, Site-to-Site and Remote Access VPNs, including AD/LDAP authentication. Worked with Threat Prevention capabilities including IPS, Anti-Virus, Anti-Bot, Advanced DNS, Threat Emulation and Zero Phishing; used Smart Log, SmartEvent and CPView for investigation and troubleshooting. Investigated VPN and application-access issues after firewall changes, including SAP Router connectivity, and corrected firewall rules based on traffic analysis. Deployed and managed SentinelOne EDR/XDR across approximately 3,000 endpoints at NLC India and approximately 1,000 endpoints at Rapid Care Transcription; monitored alerts and supported endpoint security operations. Forwarded Check Point firewall logs into the SentinelOne XDR environment and created custom dashboards using Event Search/Purple AI workflows to visualize firewall rule activity, including hit counts and rejected/dropped traffic. Investigated endpoint security alerts and suspicious activity using SentinelOne telemetry, supported malware mitigation workflows, and performed IOC-focused analysis of malicious IPs, domains and file hashes. Provided L1/L2 production support using SmartConsole, Wireshark, firewall logs and network troubleshooting methods; coordinated with support teams, collected logs/packet evidence, and documented incidents, changes and validation results.