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Tacacs for Ubuntu 20.04

TACACS for Ubuntu 20.04


This guide will walk you through the setup of a Linux based TACACS+ Authentication Server, using Ubuntu 20.04 that authenticates against a Windows Active Directory LDAP.

This guide assumes that you are familiar with installing and configuring Ubuntu Server and can deploy or have already deployed a Windows Active Directory infrastructure.


Configuring simple MPLS network


Create a simple MPLS network and observe partial parts of MPLS functionality. MPLS network consist of four routers, two edge routers - LSE1 and LSE2 whose fastEthernet interfaces are not parts of the MPLS network and two Label Switch Routers - LSR1 and LSR2 interconnected through serial lines.


Four routers are connected in a chain line topology:

How to install Microsoft Loopback Adapter on Windows 11

To install the Microsoft loopback adapter on MS Win 11 OS you must:

  1. Right-click on the window start menu icon and select Device Manager. The Device manager window will immediately open (or you may use any other way to open the device manager window)
  2. Left-click on Action, and select Add legacy hardware. The Add Hardware wizard will start.
  3. Click Next on its Welcome screen.
  4. Choose “Install the hardware that I manually select from a list” and click on Next
  5. Scroll down and select Network adapters from offered common hardware types and click on the Next button.
  6. Select Microsoft (not Microsoft Corporation|as the manufacturer, and then select Microsoft KM-TEST Loopback Adapter card model, click on the Next.
  7. Click on the Next
  8. Click on the Finish.

Setting LAN network with three VLANs on Mikrotik RouterOS switch and Cisco IOS router on-stick.

In this article, I will set up a simple LAN network consisting of two PCs, one Mikrotik box that acts as a L2 LAN switch, and one Cisco router that connects everything to the internet using NAT. PCs and Mikrotik switch are in the separate VirtualLANs (VLANs). My VLAN definition is:

  • VLAN10, name Home, network address:, Mikrotik port: Ether 2
  • VLAN20, name IoT, network address:, Mikrotik port: Ether 3
  • VLAN99, name MGMT, network address:, Mikrotik port: bridge
  • Ether port 1 will act as the trunk

Devices addresses:

Setting a simple LAN network with Mikrotik RouterOS and Cisco IOS

In this article, as the RouterOS CLI newbie, I will set up a simple LAN network consisting of two PCs, one Mikrotik box that acts as a simple L2 LAN switch, and one Cisco router that connects everything to the internet using NAT. All four devices are in the same broadcast domain and have IP addresses from the network address space :

Devices addresses:

GNS3 – How to change the Solar-PuTTY font size

To change the Solar-Putty font size follow these steps:

  1. Open the Solar-Putty SSH client (for example by opening the console of a GNS3 device)
  2. Click on three dots in the upper left corner
  3. Select Settings,
  4. Go to the bottom menu item “GENERAL
  5. Look at the bottom of the window for “FONTS & COLORS”
  6. Click on the “Launch Putty” link. As the result the Putty configuration window will be opened
  7. Click on the Default settings inside the Saved sessions
  8. At the left menu select Window => Appearance
  9. Click on the Change button and set your preferred font and its size. When you will finish click on Ok.
  10. At the left menu select “Sessions” and “Default settings” again
  11. Click on Save
  12. You may close the window now. It is done!

Here are screenshots:

Site-to-Site IKEv2 IPSec VPN using Pre-Shared Key Authentication – simple configuration example for two Cisco routers

This config example shows a Site-to-Site configuration of IPsec VPN established between two Cisco routers. VPN will use IKEv2 protocol with PreSharedKey (PSK) remote-site authentication. Topology simulates a Branch router connected over an ISP to the HQ router. There are several options for how to configure IKEv2. In this example, I’m using the symmetric PSK witch crypto map, where the IKEv2 process is started by ACL that identifies interesting traffic. I also do not use GRE tunnel for the interconnection of both sides, instead, simple static default routes are used.


Configuration runs on GNS3 emulator and I’m using the CSR1000v platform with version 16.12.01a IOS XE as the older ISR platform (7200 15.4 IOS) does not support IKEv2. On real devices, IKEv2 is supported on Cisco ISR Generation 2 (G2) that runs Cisco IOS software version 15.2(4)M or later (for example 29xx ISR), ASA with 8.4.(1) and later (including ASA 5510).

CCNA study – How to configure multiple IPv6 DHCP pools on a remote Cisco router

This config example shows how to configure three DHCPv6 pools for a network setup, where the DHCP server is running on a remote router. This situation had emerged during my remote CCNA lesson and it found me unprepared. The main problem is with the ipv6 dhcp server POOL command, that can be executed only once, all others rewrite the previous one. The solution is to use ipv6 dhcp server automatic or just pv6 dhcp server command with some additional pool command.


Configuration runs on GNS3 emulator. The Switch runs IOSv and is primarily used for the VLAN segmentation. In R1/R2 I’m using the older ISR platform (7200 15.4 IOS). CSR-1000v is also fine. Problems are with older 12.x IOSs, that do not support ipv6 dhcp server command. DHCPv6 servers/pools are configured on R2. DHCPv6 relay and nd config flags on R1 fa0/0 subinterfaces.

How to install Microstack on Virtualbox with Ubuntu guest OS

MicroStack is an OpenStack distribution for Ubuntu, which is suitable for the deployment of fully functional OpenStack on a single machine. Installation is quite straightforward.

My environment

  • Host system: Win 10 Pro 64bit
  • VirtualBox 6.1.25r 64bit
  • Guest System:
    • clear server install of Ubuntu 20.04.3 :LTS with bridged networking
    • 4GB of RAM
    • 4 vPCU
    • 100GB of HDD (the size is officially recommended, but mainly is used for hosting virtual VMs)

    Single node installation steps using snap

    Official guides use the snap system, where all applications are packaged with all their dependencies. All the microstack installation is relatively fast, taking no more than 15 minutes.