WhiteWinterWolf Practical IT security, *nix systems & networking

Latest articles in ‘Gns3’

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   • lab
   • networking
   • cisco
   • gns3

   How to install Cisco Adaptative Security Appliance (ASA) in GNS3

   The Cisco Adaptative Security Appliance (ASA) is Cisco’s main firewall and network security product. It mainly provides firewall and VPN services, but its native features can be enhanced with the addition of FirePOWER NGIDS services on top of it.

   Note

   Even when used on top of an ASA in the same appliance, the FirePOWER NGIDS is never really merged within the ASA but stays a separate module. For instance, the ASA and the FirePOWER each have their own separate CLI shell, each with their own different syntax and logic. In fact FirePOWER is not a Cisco development but has been acquired when Cisco merged with SourceFire, hence the (personal) feeling of an “alien” product plugged into the ASA.

   For CCNA Security students, while you must know ASA and be comfortable with its usage, as for now you only need to know what FirePOWER is and why it is used …

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    • lab
    • networking
    • cisco
    • gns3

    How to install Cisco Configuration Professional (CCP) in GNS3

    The Cisco Configuration Professional (CCP) is a graphical interface allowing to quickly and easily configure, monitor and troubleshoot Cisco IOS-based devices. It does exactly the same thing as one could do using IOS command-line, but using more convenient graphical tools and optional wizards for multi-steps configuration, including operations involving several devices like setting-up a tunnel.

    It comes in two versions:

    • CCP 2.x, also known as Router and Security Device Manager Software (SDM), it is the little brother of ASDM used to configure ASA firewalls. This is a desktop application, the GUI is installed locally on the user’s host.

    • CCP “Express” 3.x: this version is deployed on the Cisco devices themselves and leverage devices’ HTTP port to embed a web configuration interface. CCP Express already existed in the 2.x generation, at that time two flavors were available: the “end-user” one with reduced functionalities (the end-result was …

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    • lab
    • networking
    • cisco
    • gns3

    How to install Cisco Secure Access Control System (ACS) server in GNS3

    Cisco Secure Access Control System (ACS or CSACS) server is Cisco’s Authentication, Authorization and Accounting (AAA) server, allowing to centralize network devices users permissions and auditing.

    It supports TACACS+ (Cisco proprietary) and RADIUS (open standard, usable with non-Cisco devices) protocols. It has its own users store, which is useful for lab tests, but in real life it will most likely be connected to a Microsoft Active Directory server to centralize users credential management.

    Note

    ACS is in the process of being replaced by its successor Identity Service Engine (ISE).

    For some time, the two products were to be used together, with ACS handling authentication and authorization while ISE was focusing on hosts policy-compliance checking.

    For CCNA-Security students, as for now only ACS is really covered by the curriculum. ISE is just mentioned from time to time so you know what it is and why it is used.

    Evaluation …

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    • lab
    • networking
    • cisco
    • gns3
    • virtualization

    How to add Cisco IOS-based devices in GNS3

    GNS3 historical use-case was to act as a GUI around Dynamips to emulate Cisco devices. However, while stable, this emulation may not be as straightforward as it could be and has some limitations.

    To understand the negatives, we first need to understand how IOS-based Cisco hardware work.

    How real gear works

    Professional switch and router devices cannot be reduced to a general purpose small-factor computer with a few additional network interfaces.

    When using a general purpose computer with classical network adapters to build a router/firewall appliance, all the processing occurs at the software level, generally the operating system kernel.

    On specialized hardware such as Cisco switches and routers, the operating system (here IOS) works tightly with some underlying specific (and usually proprietary) hardware and delegates parts or all of the processing to dedicated chips, the Application Specific Integrated Circuits or ASICs, to allow faster processing.

    On general-purpose computers …

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    • lab
    • networking
    • gns3
    • virtualization

    How to add virtual machines (end devices nodes) in GNS3

    Virtual machines can be added in GNS3 topologies as end devices nodes and can play various roles:

    • Lightweight ones are very focused for instance to provide just enough to test the network connectivity or provide a functional browser.

      They start blazingly fast and are very light on resources, meaning you can put several of them to test end-user workstation behavior at several places in your topology with little to no worry about the CPU or memory impact.

    • Dedicated appliances are designed to provide a specific service, like networking (firewall, …), applicative (proxy, email filtering, …) or administrative (monitoring, …) services.

      Resource consumption vary greatly depending on the service and the software used by the appliance. However, professional appliances are usually designed to handle a large number of simultaneous operations: some will support with no issue to see the virtual machine resources settings reduced on test environments (some may require a modification in their …

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    • lab
    • networking
    • gns3
    • virtualization

    How to install GNS3 and VMware Player on Linux (Debian)

    While installing GNS3 and VMware should be easy, it in fact very easy to loose a lot of time on silly issues.

    • If you are interested only in installing VMware Player, feel free to directly go corresponding part.

    • If you are interested in installing GNS3, I also recommend to install VMware player as some appliances may require it.

    RouterGods also shared a few tips on how to setup a more comfortable GNS3 lab. Take a few minutes to check it once you’ve ended the installation!

    Installing GNS3

    GNS3 relies on Linux kernel features. If you are not a Linux user, the recommended way to use GNS3 is to use the GNS3 official virtual machine. This virtual machine may also be a good solution if you are a Linux user but you just want to quickly test GNS3 or do not want to modify your host environment.

    For a regular …

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    • lab
    • networking
    • gns3
    • virtualization
    • pentest

    How to run a CAM table overflow attack in GNS3

    Knowing where difference with real gears lies

    For performance reasons, a lot of switch things are actually not part of the IOS code but are implemented in hardware. This includes the ARL, or Address Resolution Logic, which provides all the methods to add, remove and lookup entries in the MAC address table.

    Therefore, for the NM-16ESW module to work in GNS3, Dynamips had to reimplement all these normally hardware provided services, or at least push this far enough to allow an unmodified IOS to run on it correctly.

    The sad thing is indeed that this is unfinished work, as stated in this module’s source code header:

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    /* * Cisco router simulation platform. * Copyright (c) 2006 Christophe Fillot (cf@utc.fr) * * NM-16ESW ethernet switch module (experimental!) * * It's an attempt of proof of concept, so not optimized at all at this …

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