Sync geth from a trusted execution-layer peer instead of beacon node

Question

I have an existing hierarchical setup of my geth nodes, where the mission-critical Private node runs in a hardened environment only being able to talk to the Border node, which in turn talks to the outside world.

[Private geth] ---|Firewall|---> [Border geth] ----> Internet
                                      ^
                                      |
                                   [prysm] --------> Internet

As shown above, I've added a PoS beacon node (prysm) after the Merge in order to get my Border node synced (otherwise it would not anymore).

Now I'm trying to get my Private geth node synced without connecting it to prysm itself (for operative and security reasons outside of scope of this question).

The connection between the Private and Border geth nodes has been set statically, and now I've even added the Border node as "Trusted" on the Private one (admin.addTrustedPeer), but that doesn't help. The Private geth node is stuck and won't sync anymore after the Merge.

Is there any way to configure the Private node to trust the Border node enough to take the information about the chain tip from it?

Note: both geth nodes are running in full-sync mode so they are capable of verifying the validity of blocks and transactions autonomously. It's just the consensus about the chain tip that I assume I need to push from Border to Private in a trusted way.

Answer 1

I'm also interested in doing this. Might not be possible, as far as I can tell.

Fundamentally geth needs a beacon node to tell it what the current correct tip is based on the consensus. I'm not sure why there isn't a supported way to either:

• Sync up to a particular, user-supplied tip, for example when you want to sync a new execution node from scratch to swap in for an existing one.
• Sync to a whatever a given JSON RPC endpoint reports as the tip. This would let you do what you're describing.