Cisco VPNs with GNS3 Labs: Practical GRE, IPSec, DMVPN labs

This hands-on GNS3 lab teaches configuring a GRE tunnel across a simulated internet, with IPsec encryption, using RFC 1918 addresses and BGP, plus DHCP and Ubuntu client verification.

Configure dhcp on the two customer routers’ gigabit zero one, assign a static ip on gigabit zero zero, set up dhcp pools for Ubuntu clients, and verify bindings before tunneling.

Configure a GRE tunnel between two customer routers, assign IP addresses (DHCP or static), observe encapsulation, and enable ibgp across the tunnel to exchange routes.

Configure an ipsec lab in Gns3 by setting up ipsec vpn between customer routers, creating dhcp pools for Ubuntu clients, enabling nat, and validating connectivity to cisco.com across the tunnel.

Configure an IPsec VPN between two routers with static routes, dhcp pools, and nat. Validate tunnel connectivity using Ubuntu clients in a GNS3 lab.

Understand how IPsec tunnels encrypt traffic and protect sensitive data, as Wireshark shows cleartext ICMP between endpoints versus encrypted ESP payload between routers.

Configure a dmvpn lab in gns3 that uses bgp on isp routers across two as, establishing a hub-and-spoke full-mesh vpn with gre and ipsec, plus dhcp and nat for Ubuntu.

Configure DMVPN using BGP, GRE, and IPsec across a three-router topology, establishing iBGP between ISP routers, advertising networks, and validating VPN tunnel connectivity in a GNS3 lab.

Configure DMVPN labs with BGP over GRE and IPsec, using loopback update sources, establishing internal and external neighbors, IGP integration, and verifying prefixes through BGP show and reachability tests.

Configure a DMVPN with BGP, GRE, and IPsec across a full-mesh topology with the hub site, verify OSPF and BGP routes, and configure DHCP pools for Ubuntu clients.

Demonstrates configuring a dmvpn hub-and-spoke with bgp, gre, and ipsec, using a vpn config generator to automate tunnel setup and verify connectivity.

Configure a full-mesh dmvpn with static and dynamic tunnels using bgp across hub and spoke sites, testing connectivity with ping and dmvpn outputs; plan nat for ubuntu clients.

Configure nat on customer routers for dmvpn, enable ip nat inside/outside with overload, verify dns and internet access for ubuntu hosts, and prepare to enable encryption on the vpn tunnels.

Enable ipsec encryption on dmvpn tunnels and configure isakmp policy, transform set, and ipsec profile in the gns3 lab, then verify encrypted traffic and BGP/GRE with ping and show commands.

Configure for DMVPN: set up BGP, GRE, and IPsec across multiple customers, establish tunnel and crypto peer relationships, and verify encrypted connectivity via ping tests.

Configure a dynamic ipsec vpn using fully qualified domain names, with dhcp on internet interfaces, nat, and dns; verify ubuntu clients and cisco.com reachability as ip changes.

Configure dynamic ipsec vpn between two customer routers using dhcp on the internet facing interfaces, create dhcp pools, enable nat, verify reachability, and establish a dynamic ipsec tunnel.

Configure dynamic IPsec VPNs between two Cisco routers using a VPN config generator, handling dynamic IP addresses on both sides, NAT, IPsec, pre-shared keys, and ping-based testing for encryption.

Explore how dynamic IP addresses affect a site-to-site IPsec VPN, using DNS lookups (FQDN) instead of hard-coded IPs, and updating the DNS server to reestablish connectivity.