Network simulation tools allow students (e.g people studying for Cisco Exams) to easily learn the core concepts of computer networking and TCP/IP in general. Even professionals could benefit from these tools by simulating network environments and get an idea of how a network will work before actual implementation. Moreover, system administrators could use them as […]
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Nowadays enterprises should deploy any available defenses they have available in order to eliminate, or at least minimize, possible attacks in their networks. Security controls should start from the network itself and span the whole IT infrastructure up to the application level. In this article I will describe a simple and effective security protection which […]
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Firewall management is one of the most challenging aspects of enterprise network security. The main issue is that many enterprise networks are complex, they contain a blend of many different vendors and technologies and this makes it time-consuming and difficult to maintain and support. The big hardware firewall vendors (like Cisco, Checkpoint, Fortinet, Palo Alto […]
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If you’re reading this article right now, you’ve already utilized the client-server model without even realizing it. You (as the client) have requested a resource (i.e this webpage) which was served to you by a webserver. This is the prevailing architecture for modern communications whereby digital data is offered by servers to clients. The alternate […]
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Cisco devices are very reliable. I remember one day I run the command “show version” on a Cisco switch and showed me an uptime of around 8 years!! That switch was up and running for 8 years in a row without failing or being rebooted even a single time! There are thousands of Cisco devices […]
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An Internet Protocol (IP) Address is a term that you will hear a lot if you are into any field of Information Technology. Especially people in TCP/IP networking have to deal with IP addresses in their every-day professional life. Just like any house or building in the world has a unique postal mail address in […]
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Although the Cisco ASA appliance does not act as a router in the network, it still has a routing table and it is essential to configure static or dynamic routing in order for the appliance to know where to send packets. When a packet arrives to a network interface on the ASA firewall, the packet […]
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The following article describes how to configure Access Control Lists (ACL) on Cisco ASA 5500 and 5500-X firewalls. An ACL is the central configuration feature to enforce security rules in your network so it is an important concept to learn. The Cisco ASA 5500 is the successor Cisco firewall model series which followed the successful […]
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An Access Control List (ACL) is a list of rules that control and filter traffic based on source and destination IP addresses or Port numbers. This happens by either allowing packets or blocking packets from an interface on a router, switch, firewall etc. Individual entries or statements in an access lists are called access control […]
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Syslog is the De Facto standard used in Networks for sending/receiving Log messages from IT systems, network devices, hosts etc. The Syslog protocol runs over port UDP 514 and is based on the IETF RFC 5424 standard. Almost all network connected devices (routers, switches, firewalls, Unix systems, Windows systems etc) support the Syslog protocol for […]
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As network engineers we are usually assigned various tasks related to the life-cycle of networks, starting from the initial design, procurement, installation of network equipment and then management and monitoring of existing networks. In the latter phase (management and monitoring of networks) we are constantly faced with major or minor problems such as links going […]
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IP version 6 (IPv6) is the new version of the Internet Protocol (IP), intended to replace the older IPv4 which is still employed on the vast majority of Internet hosts. IPv6 increases the IP address size from 32 bits to 128 bits to support a much greater number of addressable hosts. IPv4 can support 232 […]
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In this tutorial we will see a special case of high availability scenario using HSRP with object tracking. Most modern enterprise networks in today’s deployments require some form of high availability depending on the uptime needed and the criticality of the service. The network infrastructure elements that are usually needed to be highly-availability include network […]
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