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Service high availability using open-source tools (part 2)

07.04.2011

[Introduction] This article is a continuation of "Service high availability using open-source tools" . Here we will describe the process of relatively complex cluster configuration with several nodes (more than two). [Cluster architecture] Description Typically, a cluster consists of four nodes. Let’s name them: Node_A Node_B Node_C Node_D

Remsys IMP success story

29.03.2011

Remsys has been offering services in the IT outsourcing market for over 9 years. Our customers are very diverse, and so are their servers and configurations. At a certain point, companies using large numbers of servers run into the following issues: "How do we organize all of the chaos that we run on servers? How can the workload that the system administrators are facing be reduced? How can IT processes be optimized?" As a growing organization, we were continuously seeking answers to these questions. And almost all of them were answered, after we discovered and examined The Puppet’s features.

18.02.2011

Our story started when we upgraded bandwidth for file servers to 1Gbps. We've analyzed RRD charts and found out that bandwidth usage is almost the same as before upgrade. 1Gbps service is not cheap, but this was not the problem we encountered. We wanted to provide better service for customers, so it was a new puzzle for us. First of all, we made sure that the interface operates in full-duplex mode. Then we checked ports on the switch. We did some download/upload tests. We've talked with datacenter's support and etc. In a nutshell, it was a slow and boring process. However, the results of the verifications were quite interesting.

VoIP PBX server failover.

08.02.2011

1. Introduction The main goal of this project is to ensure critical service like VoIP to be operational with minimum downtime in case of emergency, network congestion or hardware failure. Also this failover schema could be used with servers in different geographical location and on different ISP or virtual office environment. Such schema provides minimum in situations when for some reason the network is inaccessible for short time period up to 5 min due to congestion or wire unplugged. System is based on bash scripts and we are using only basic system tools thereby it is not hard to use it and its resources usage is low.

How to write your own plugin for cPanel

31.01.2011

To write your own plugin for cPanel it is not necessary to be a system administrator or a cPanel guru. Anyone, who can write code in PHP should be able to handle this task easily. Our first plugin was written within a day. With this how-to guide you will be able to do this within about 20 minutes. Let’s begin. To get started you will need a good idea for a plugin. If you do not have one, do not waste time. In this how-to guide, our idea is to make a magic button which displays “First cPanel Plugin!” when you click on it.

RSMON distributed monitoring system

02.12.2010

[Introduction] This article describes RSMON distributed monitoring system basic principles and may be interesting for specialists interested in increased reliability of monitoring as well as in monitoring centralization, flexibility and minimization of false states.

VoIP Security

08.09.2010

[Introduction] In this article you will find descriptions of major VoIP attacks and two ideas on securing VoIP networks. The first suggestion is dialing the network with a VoIP operator infrastructure. The second suggestion is referral to company asterisk based PBX, which is an open source switch server with limited access. In VoIP many protocols are used. In this article we will focus on the most popular protocol, SIP. SIP is the acronym for Session Initiation Protocol (IETF RFC 3261) that is a widely utilized standard in VoIP communications to set up and control (transfer, hold, cancel, etc.) phone calls.

Security audits

24.08.2010

[Introduction] Please note that this article is about practical side of security audit. You can easily find many teoretical materials on this subject (for example at wikipedia http://en.wikipedia.org/wiki/Information_technology_security_audit). One of our customers asked us to make a security audit of his server. He had suspicions that his system has been compromised (this indirectly has been confirmed by the increased load, which was not so high before). He had a CentOS 5.4 server running Apache, MySQL, vsftpd server and so on. In a nutshell, it was a typical LAMP configuration.

10.06.2010

Reference: http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html Assumptions: Server1 IP: 10.1.1.1 Server2 IP: 10.1.1.2 We will completely replicate all databases Servers are not in production yet. If they are – be careful when rsyncing data Notes:

Referral Whois and ARIN's rwhoisd

08.06.2010

Without strict standards, the Internet would have been just a bunch of interconnected networks, and finding valid information about some specific resource would have been next to impossible. The most simple example (not directly related to the Internet or IT, but illustrating the main idea): Imagine the modern telephone system. Each country has its own area code, each state/district/region has its own area code too, inside the country. Each smaller region has an area code too. For example, you want to call someone in Vienna, Virginia, with the local number 123 4567.

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