Setup and Environment

Host A is Ubuntu VM (GNS3). All other Servers are RedHat.

Network Path

[Host A(x.x.y.b) --via-- Host B (x.x.y.a)] ----|---- [Host C (x.x.z.c) & Host D (x.x.z.d)]

  1. Host A is hosted in Host B as a VM. Using of static route all the other hosts in subnet x.x.y.* are able to ping Host A via Host B.
  2. Host C, D lie in a different subnet, hence cannot add static route via Host B.

Recommended Solutions for similar question online:

  1. Adding routes in routers - I do not want to configure the routers
  2. VPN over SSH/PermitTunnel and Autossh - I might have to create 1 tunnel each for all the servers to connect.
  • To confirm, the VM is using a bridged network interface with the host to expose its IP, right? – Wanted Apr 30 at 20:09
  • Yes.The traffic flow happens via the Host B. – Pavan Apr 30 at 20:17
  • 2
    I wonder why you'd need to add static routes, even on hosts in the same network as host B. If the virtualization software is configured to use bridged network interface, then the VM should simply be visible to other machines in default configuration, by responding to ARP requests, pings etc. You can serve multiple IPs from one physical interface. Maybe your virtualization software is blocking external network traffic, or some built-in RedHat firewall (check iptables)? – Wanted Apr 30 at 20:53
  • Yes, you are correct and to the point as far as routing between Host A and Host B. I have modified the IP tables and static routes to allow only required routes, I designed it that way to separate the private gns3 config from rest of the networks, to prevent accidental injection of any private network routes from gns3 projects. Hence preferred to go by adding static routes. My question however is more pointed towards enabling connection between Host A to Host C,D...(in the other subnet). – Pavan Apr 30 at 21:30
  • 1
    If host a has a bridged adapter, it should be able to ping the gateway (x.x.y.1, probably). Does that work? Is the default gateway of a the same as of b? Is the router between x.x.y.0/24 ans x.x.z.0/24 a normal router or a soho/nat type router? Have you put a static route from c and d with gateway the router between the two subnets? Or is there not a single router but a complete network between the two subnets? – Ljm Dullaart May 1 at 9:26

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