In the previous post, we have discussed about isolating traffic using the private VLAN feature at Layer2 level. In this tutorial, we will discuss traffic isolation at Layer3 level using VRF Lite on Cisco routers. What is VRF Lite VRFs employ essentially the same concept as VLANs and Trunking, but at Layer 3. VRF (Virtual […]
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The internet and intranet are closely related terms. Some individuals may get these terms confused or use them interchangeably. While there are similarities, the internet and intranet are used for very different purposes. What Is an Internet Network? When you visit a website or use a mobile app that requires an internet connection, you are […]
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We have two types of IPSEC VPNs: Lan-to-Lan (or site-to-site) encrypted VPN and Remote Access VPN. The first one is extensively used to securely connect distant office networks and the second one for allowing remote users/teleworkers to access resources on a central site network. In this post we will describe briefly a Lan-to-Lan IPSEC VPN […]
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On this website I have written tens of articles about enterprise level firewalls (especially Cisco ASA) but many people are interested to learn about the best hardware firewalls for home or small business networks, so this is what I’ll focus in this article. Firewalls are designed to monitor incoming and outgoing traffic, helping to keep […]
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Denial of Service attacks (DoS) are very common these days. Especially Distributed DoS attacks (called also DDoS) can be executed quite easily by attackers who own large networks of BotNets. Thousands of malware-infected computers (which comprise the so called “BotNets”) are controlled by attackers and can be instructed to start attacks at any target. Usually […]
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Cisco Adaptive Security Appliance (ASA) is quite a versatile device integrating application-aware firewall, SSL and IPsec VPN, intrusion prevention system (IPS), antivirus, antispam, antiphishing, and web filtering services. Cisco ASA also supports routing protocols such as Routing Information Protocol (RIP), Enhanced Interior Gateway Routing Protocol (EIGRP), and last but not least, Open Shortest Path First […]
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The Cisco 800 series routers are part of the “Branch Office” category, used mainly for SOHO purposes or for connecting remote branch offices to a central location. They are “fixed hardware configuration” devices, meaning that they don’t have any plug-in hardware slots for inserting additional interfaces to the device (all the interfaces are fixed). All […]
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The “ping” command has been the “de facto” troubleshooting protocol used mainly for testing connectivity and communication between two hosts. As we all know, the ping command sends “ICMP” packets to the other end and waits for ICMP reply packets to come back. From ASA 8.4(1) and later, Cisco introduced an enhanced version of the […]
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SNMP stands for Simple Network Management Protocol. Up to ASA software 8.1, the SNMP version supported was v1 and v2c. The newest ASA software 8.2 supports also SNMP v3 which is the most secure snmp protocol version. The ASA works as an SNMP server (or agent), so you need also a Network Management System (NMS) […]
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One of the advantages of the Cisco ASA firewall is that you can configure multiple virtual interfaces (subinterfaces) on the same physical interface, thus extending the number of security zones (firewall “legs”) on your network. Each subinterface must belong to a different Layer2 VLAN, with a separate Layer3 subnet. There are limits on the number of […]
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NMAP (Network Mapper) is the de facto open source network scanner used by almost all security professionals to enumerate open ports and find live hosts in a network (and much more really). One of my responsibilities in my job is to perform white hat penetration testing and security assessments in corporate systems to evaluate their […]
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HSRP (Hot Standby Router Protocol) is the Cisco proprietary protocol for providing redundancy in router networks. The standard router redundancy protocol which is used by other vendors is VRRP (Virtual Router Redundancy Protocol), however Cisco has created its own proprietary protocol (HSRP) which works very well on Cisco routers. In a Local Area Network (LAN), […]
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Network infrastructure devices (routers, switches, load balancers, firewalls etc) are among the assets of an enterprise that play an important role in security and thus need to be protected and configured accordingly. Many enterprises focus on protecting their data, servers, applications, databases etc but they forget about security of network devices which are sometimes installed […]
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