Performance Analysis Tools

Basic Tools In 2015, Brendan Gregg posted two great articles on Netflix blog: Linux Performance Analysis in 60 seconds, and Linux Perfomrance Tools. They have great value when I was in a urgency to spot performance issues. The articles cover the essential tools for performance troubleshooting, including: Check out load averages: uptime or w Print … Read morePerformance Analysis Tools

Network Analyzer: Capture filter and Display filter

Capture filter is set before collecting packets. It is applied at the time of data acquisition and it impacts the size of the capture. It does not have as many variations as display filter and is usually not aware of protocols above TCP/UDP layer. A common form of capture filter is BPF (Berkerly Packet Filter) … Read moreNetwork Analyzer: Capture filter and Display filter

Introduction to Authentication Frameworks (PAM and SSPI)

This article gives a very brief high-level introduction to PAM (Pluggable Authentication Module) and SSPI (Security Support Provider Interface) as authentication frameworks in Linux and Windows respectively. PAM The Pluggable Authentication Module (PAM) architecture provides a powerful abstraction for user IAM using pluggable authentication model Unix platforms. It defines a generic API for authentication and … Read moreIntroduction to Authentication Frameworks (PAM and SSPI)

Lightweight Directory Access Protocol (LDAP)

Introduction Originally LDAP only refers to the connectivity protocol to the directory server. This term is being used loosely today and it also refers to the actual directory service that supports and complies with LDAP. LDAP v3 is the current version developed in RFC 2251. A directory is information about some set of entities such … Read moreLightweight Directory Access Protocol (LDAP)

Networking Basics 3 of 3 – common network protocols and technologies

The 5 layer TCP/IP model (or its more rigorously defined alternative OSI model) leads to a whole world of network protocols. Understanding these new protocols requires one to map it out agains the network layers (e.g. at Layer 4 whether it is TCP or UDP, etc) . VPN is a whole family of technologies with … Read moreNetworking Basics 3 of 3 – common network protocols and technologies

Networking basics 2 of 3 – Layer 4 and common network configurations

Transport Layer Transport Layer handles multiplexing & de-multiplexing through ports. Port is more or less a virtual concept. Source port is usually ephemeral. Two dominant protocols are TCP and UDP. TCP relies on acknowledgement. TCP control flags are SYN, ACK, FIN, URG, PSH, RST, ECE, CWR. TCP connection is established by 3-way handshake and torn … Read moreNetworking basics 2 of 3 – Layer 4 and common network configurations

Storage Nitty-Gritty 5 of 5 – Replication

Replication Terms PIT (point in time) replica – snapshot of the source at some specific timestamp;Continuous Replica – always in-sync with the production data;Recoverability – enables restoration of data from the replica to the source if data loss or corruption occurs;Restartability – enables restarting business operations using the replicas; Local Replication Use Case: Alternative source … Read moreStorage Nitty-Gritty 5 of 5 – Replication

Networking Basics 1 of 3 – Layer 1 through Layer 3

What layer model works the best? Back in university my textbook was based on OSI 7-layer model. It is rigorously defined and often used in academics. When it comes to day-to-day operation, the 5-layer TCP/IP model is more useful. It combines Application, Presentation and Session layers in OSI model into a single Application layer. Physical … Read moreNetworking Basics 1 of 3 – Layer 1 through Layer 3