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I wanted to know if this is a valid scenario and if it is possible to implement.

There is a remote site A. and a Data center site B. Both A and B have a edge router which runs an IPSec tunnel. An Access Point(Linux machine) in Site A supports setting up a GRE tunnel endpoint. And at Data center also has a GRE tunnel endpoint (on another Linux Machine). Is it possible to setup a GRE tunnel between Access Point and Linux Machine in Data center, such that packet first gets GRE encapsulated at access point and then gets encrypted using IPsec on the edge router at site A. Then gets decrypted at site B edge router and reaches GRE endpoint B.

Basically, I want to get DHCP for clients connected to my access point via the GRE tunnel from the DHCP server running in Data center. In between this GRE encapsulated DHCP also need to be encrypted with IPSEC.

Something like this: enter image description here

Thanks

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  • GRE is an IP protocol, so it has no idea what may be involved in higher layers, including any other tunnels through which it flows. It's just IP packets with protocol 47 to everything outside the tunnel. Note: you can apply ipsec to gre so it's payload is encrypted.
    – Ricky
    Jul 25, 2023 at 3:27

1 Answer 1

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Is it possible to setup a GRE tunnel between Access Point and Linux Machine in Data center, such that packet first gets GRE encapsulated at access point and then gets encrypted using IPsec on the edge router at site A.

Completely possible. Just make sure the GRE tunnel endpoints are using IP addresses routed through the IPsec tunnel.

However, what's your point in using GRE? You should be able to route DHCP requests through IPsec directly using DHCP relay, same as with GRE.

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  • GRE tunnel is needed so that if any other site also wants to connect to same data center then they can be in the same network. Jul 24, 2023 at 13:19
  • @RootPhoenix I'd generally advise against L2 over WAN links as they usually don't work as well as you need them to and can be quite cumbersome.
    – Zac67
    Jul 24, 2023 at 16:43

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