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Tag: DHCP

  • Enable/Configure DHCP Snooping in Cisco Catalyst Switches (IOS)

    DHCP snooping is a DHCP security feature that provides security by filtering untrusted DHCP messages and by building and maintaining a DHCP snooping binding table. An untrusted DHCP message is a message that is received from outside the network or firewall causing denial of service attacks.

    The DHCP snooping binding table contains the MAC address, IP address, lease time, binding type, VLAN number, and interface information that corresponds to the local untrusted interfaces of a switch. An untrusted interface is an interface that is configured to receive messages from outside the network or firewall. A trusted interface is an interface that is configured to receive only messages from within the network.

    DHCP snooping can be enabled on the switch per vlan as it can intercept the DHCP messages at the layer2.

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  • Yersinia – Free Network Testing tool for CDP,STP,VTP,DHCP,DTP,ISL,802.1Q,802.1X

    Yersinia is a free Network Penetration testing tool used to test and analyse some of the most commonly used protocols on your network. Penetration testing tools of this kind will provide deep insight on network security issues. Yersinia is a UNIX based tool that works on Linux, Solaris 8, FreeBSD.

    NOTE: The tool is described as a tool to perform network tests and exercise responsible actions when performing tests which includes obtaining the permission from responsible authorities. DO NOT USE THIS TOOL FOR ANY UNAUTHROSIED HACKING PURPOSES

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  • Dnsmasq – Opensource DNS Server Forwarder & DHCP Server

    Dnsmasq is an opensource light-weight,easy to configure and administer DNS and a DHCP Server. Dnsmasq is ideally suitable for smaller networks like Small Office and Home Office networks (SOHO) and branch office networks. Dnsmasq can be run on old PC and is very easy to configure and administer. Dnsmasq is seen to support upto 1000 nodes on a network.

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  • DHCP Relay Agent for subnets without a DHCP Server

    A DHCP server is the one which provides a network client with a unique IP address, Subnet mask, Gateway and DNS server IP address automatically when it connects to the network.

    A DHCP Relay Agent is a computer, server or a Router in a particular subnet which receives a DHCP client broadcast and relays it to a DHCP server in another network or a subnet. A DHCP Relay Agent is more a helper agent here that gets the client a DHCP lease.

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  • Smoothwall Express 3.0 – Opensource Firewall

    Are you throwing away your old PC??? Think again!!

    Smoothwall Express 3.0 [Codename: POLAR] is a free opensource linux based firewall which can installed and be up and running in just in minutes. Smoothwall Express 3.0 is licensed under GPL license.

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  • Number 87 haunts Windows 2003 DHCP server

    We recently ran into this problem wherein the DHCP MMC started throwing errors anytime we try to launch it. After a good length of troubleshooting, we found that the number of reservations on the DHCP were 87. Sounds crazy???

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