Author Archives: genis

Learn how to learn

Notes taken from the Coursera course Lean how to learn Focus mode – focused in a subject. no distractions Diffuse mode – not focused in a subject. jumping from one thing to another – creating new neuronal paths Spend less time but more focused Diffuse mode situations: Moment just before sleeping Doing sports Changing to… Read More »


DNS stands for Domain Name System Types of DNS servers: Authoritative server – The server has authoritative information about the queried domain and it will respond the request with the information in its local database. Not configured as a recursive resolver – The server will respond with a DNS Referral Response message to inform the client where… Read More »

Riverbed WAN Optimization

Introduction: WAN Optimization are useful on a high latency links (>200ms?). 60-90% data Steelhead devices are setup in-path. WAN Optimization techniques Compression at the TCP packet level Scalable Data Referencing – Data is stored on the local Steelhead with a pointer. If the remote Riverbed sees a block of data that has already been sent, it send… Read More »

Check Point Commands

Basic setup set expert-password set management interface eth1 set interface eth1 ipv4-address IP mask-lenght MASK set interface eth1 state on save-config Operating Reboot / shutdown expert> shutdown -h now reboot CPConfig – Reset SIC. Admin users. Enable functions. Cluster membership cpconfig Start and stop CP services cpstop cpstart Initial setup reconfiguration tool cpconfig FTP ftp IP… Read More »

Check Point Architecture

Technology Architecture Components SMART – Check Point Security Management Architecture Core systems: SmartConsole – Windows based GUI Security Management Server (SMS) (aka Smart Center Server) – Configuration and log storage Security Gateway – Security Device (SGW) Deployment modes Stand alone – Security Management Server + Security Gateway in the same device Distributed – Security Management… Read More »


MTU – Maximum transmission unit PMTUD – Path MTU Discovery Links have a maximum packet size limitation depending on the protocol/technology. MTU defines the maximum bytes of a packet on a link. With PMTUD, endpoints are capable of determine the MTU of a path. When a endpoint sends a packet larger than the MTU, this is fragmented on… Read More »

Google Hacking

Basic concepts “search a phrase” search anythin but -not -include -these -terms wildcard symbol * OR Operator |   Google URLs lr – search for specific language – lang_ca, lang_es &lr=lang_ca hl – changes the language of the google interface – ca, en, es &hl=en restrict – restrict search for country (domain or server location)… Read More »


Export saved sessions To move the saved sessions list to another computer, export the registry HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\Sessions and import it in the new computer. If no admin rights are available with the user, browse to the right user folder on the registry


Routing Protocols Distance-Vector Protocols: RIPv1, RIPv2, IGRP, EIGRP Based on Bellman–Ford algorithm, Ford–Fulkerson algorithm or DUAL FSM A node inform to the neighbors about the topology changes. Each node doesn’t have knowledge of the entire path to a destination. They know about the direction and the distance to its destination. Less computational complexity and message overhead. Best route… Read More »


  Hash Algorithm Message Digest – MD2, MD4, MD5 Secure Hash Algorithm – SHA-1, SHA-256. SHA-384, SHA-512 When hashing the passwords for storage or transfer, avoid the use of the rainbow tables using a salt. Diffie-Hellman Key management protocol   Asymmetric Confidentiality – Use the public key of the target. The target will use the… Read More »