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Creating a network with Internet access in a GNS3 environment on Windows 10

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GNS3 (Graphical Network Simulator) – is a graphical network simulator that allows you to simulate a virtual network of routers and virtual machines. An indispensable tool for training and testing. Works on almost all platforms. Great for creating testbeds on desktop machines.
Depending on the hardware platform on which GNS3 will be used, it is possible to build complex projects consisting of Cisco routers, Cisco ASA and Juniper routers, as well as servers running network operating systems.
GNS3 has two serious drawbacks :

  • Highly demanding on CPU and memory. 10 routers will already seriously stress the PC. CPU usage can be reduced with the Idle PC mechanism. Without it and 3-4 would probably be hard to go.
  • Very little support for L2 functions. There are only similar switches on which you can configure Access/Trunk ports at most and switch boards for routers, the L2 functionality of which is also very limited.

In addition to that, you need to get the IOS images somewhere else. GNS is basically a virtual router and to run it, it also needs software, which is IOS.
The program window and its structure are shown below.
Creating a network with Internet access in a GNS3 environment on Windows 10
Since the task goes beyond simulating the network inside the emulator, we need to prepare the operating system for further interaction with GNS3. To do this, we need to set up a network that interacts with GNS3 rather than with external data transfer protocols. All networks that are connected to the computing machine are aimed at transferring files outside its system. The machine translates files into bits, assembles them into packets, tags them, and sends them via TCP/IP to the network. The receiving machine does not interact with the network, but with the transmitted packet. It unpacks it with the same TCP/IP protocol and gives the file to the user through its file system. Our task is to let the traffic flow in such a way that the computer simulates the network inside itself and analyzes the response to its own request on the network. The task is not a simple one, but there is a complicating fact – Wi-Fi. Cable networks are easy to build on the emulator, as well as wireless, but to emulate a network that operates according to certain principles of simplified transmission – it is not so easy. To solve the task at hand, let’s create a loop-back adapter. It is a network that talks to itself. To create a loop-back network in Windows Win+R and type hdwwiz.exe
Creating a network with Internet access in a GNS3 environment on Windows 10
Creating a network with Internet access in a GNS3 environment on Windows 10
Press the "Next" button and select the item "Installing the equipment selected manually from the list". I should point out that I used the Windows 10 (64 bit) operating system in this lab work, as it is the latest and most up-to-date.
Creating a network with Internet access in a GNS3 environment on Windows 10
Press the "Next" button and select "Network Adapters".
Creating a network with Internet access in a GNS3 environment on Windows 10
Press the "Next" button and select Microsoft in the left menu and "Microsoft KM-TEST self-closing adapter" in the right menu
Creating a network with Internet access in a GNS3 environment on Windows 10
Next, perform the installation and go to the adapter settings. To do this, go to Start -> Control Panel -> Network and Internet -> Network and Sharing Center -> Change Adapter Settings.
Next we need to configure the system so that our lookback network has access to the Internet. To do this, go to the properties of the wireless network and in the tab "Access" check the "Allow other users of the network to use the Internet connection of this computer" and "Allow other users of the network to manage Internet connection sharing". If you have more than one network, select the closed network that we have created, as it will not work with other networks.
Creating a network with Internet access in a GNS3 environment on Windows 10
If you have done everything correctly, you should have two networks with these transcripts :
Creating a network with Internet access in a GNS3 environment on Windows 10
In my case, "Wireless 2" is a Wi-Fi network, and "Ethernet 3" is a closed network.
The preparatory work on the system is over. I won’t tell you how to install the ISO images on GNS3 because each user has different versions and each system has different routers. I used version 0.87 and the c3660 router because it is the most stable router in my version.
Drag and drop the router and the cloud onto the workspace to get a diagram like in the figure below
Creating a network with Internet access in a GNS3 environment on Windows 10
Let’s set up the cloud. Go to the NIO Ethernet (Network Input Output Ethernet) tab, select our closed network and click "Add" and then OK.
Creating a network with Internet access in a GNS3 environment on Windows 10
Connect the cloud and the router with a FastEthernet cable and start the router by pressing the green "Play" button.
Let’s set up the router. Let’s enter the command sequence :

conf tint fa 0/0no shutip address dhcpip domain-lookup

Let’s break down each command.

conf t (global configuration mode)
int fa 0/0 (Interface configuration mode)
no shut (interface enable command)
ip address dhcp (indicates that the interface gets its IP address via DHCP)
ip domain-lookup (resolve hostnames to IP addresses and vice versa)

Now we need to check if there is a connection to the internet. To do this, ping any site. For example, google.
Creating a network with Internet access in a GNS3 environment on Windows 10
As you can see in the screenshot, everything works.
Additionally I will attach a dump of the router settings, because the procedure was more complicated than it seems at first glance.

Connected to Dynamips VM "R1" (ID 0, type c3600) - Console portPress ENTER to get the prompt.This product contains cryptographic features and is subject to UnitedStates and local country laws governing import, export, transfer anduse. Delivery of Cisco cryptographic products does not implythird-party authority to import, export, distribute or use encryption.Importers, exporters, distributors and users are responsible forcompliance with U.S. and local country laws. By using this product youagree to comply with applicable laws and regulations. If you are unableto comply with U.S. and local laws, return this product immediately.A summary of U.S. laws governing Cisco cryptographic products may be found at:http://www.cisco.com/wwl/export/crypto/tool/stqrg.htmlIf you require further assistance please contact us by sending email toexport@cisco.com.Cisco 3660 (R527x) processor (revision 1.0) with 124928K/6144K bytes of memory.Processor board ID FTX0945W0MYR527x CPU at 250MHz, Implementation 40, Rev 1.2, 512KB L2 Cache3660 Chassis type: ENTERPRISE2 FastEthernet interfacesDRAM configuration is 64 bits wide with parity enabled.125K bytes of NVRAM.8192K bytes of processor board System flash (Read/Write)SETUP: new interface FastEthernet0/0 placed in "shutdown" stateSETUP: new interface FastEthernet0/1 placed in "shutdown" statePress RETURN to get started!*Mar 1 00:00:03.091: %LINEPROTO-5-UPDOWN: Line protocol on Interface VoIP-Null0, changed state to up*Mar 1 00:00:03.183: %SYS-5-CONFIG_I: Configured from memory by console*Mar 1 00:00:03.319: %LINEPROTO-5-UPDOWN: Line protocol on Interface IPv6-mpls, changed state to up*Mar 1 00:00:03.463: %SYS-5-RESTART: System restarted --Cisco IOS Software, 3600 Software (C3660-A3JK9S-M), Version 12.4(15)T14, RELEASE SOFTWARE (fc2)Technical Support: http://www.cisco.com/techsupportCopyright (c) 1986-2010 by Cisco Systems, Inc.Compiled Tue 17-Aug-10 11:00 by prod_rel_team*Mar 1 00:00:03.467: %SNMP-5-COLDSTART: SNMP agent on host R1 is undergoing a cold start*Mar 1 00:00:03.491: %LINK-5-CHANGED: Interface FastEthernet0/0, changed state to administratively down*Mar 1 00:00:03.503: %CRYPTO-6-GDOI_ON_OFF: GDOI is OFF*Mar 1 00:00:03.507: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is OFF*Mar 1 00:00:03.507: %CRYPTO-6-GDOI_ON_OFF: GDOI is OFF*Mar 1 00:00:03.507: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is OFF*Mar 1 00:00:03.543: %LINK-5-CHANGED: Interface FastEthernet0/1, changed state to administratively down*Mar 1 00:00:04.491: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down*Mar 1 00:00:04.543: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to downR1#R1#conf tEnter configuration commands, one per line. End with CNTL/Z.R1(config)#int fa 0/0R1(config-if)#no shutR1(config-if)#*Mar 1 00:00:45.887: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up*Mar 1 00:00:46.887: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to upR1(config-if)#ip address dhcpR1(config-if)#*Mar 1 00:01:13.071: %DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/0 assigned DHCP address 192.168.137.31, mask 255.255.255.0, hostname R1R1(config-if)#ip domain-lookupR1(config)#^ZR1#*Mar 1 00:02:15.551: %SYS-5-CONFIG_I: Configured from console by consoleR1#ping google.ruTranslating "google.ru"...domain server (192.168.137.1) [OK]Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 173.194.73.94, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 28/35/44 msR1#

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