fix(gw01): masquerade tailnet clients into the sandbox VLAN - #19
Merged
Conversation
Tailnet-member hosts on VLAN 40 (sandbox01) reply to tailnet client addresses through their own tailscale0 peer routes instead of gw01, so un-SNATed subnet-routed traffic gets dropped asymmetrically. Masquerading 100.64.0.0/10 out br40 keeps replies symmetric. Home and inter-VLAN traffic remain un-NATed.
jmgilman
added a commit
to GilmanLab/root
that referenced
this pull request
Aug 26, 2026
Companion to GilmanLab/networking#19, which masquerades 100.64.0.0/10 out br40 so tailnet-member sandbox hosts reply symmetrically.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
Tailscale clients using the
glab-vyos-subnet-routerroute to10.10.0.0/16cannot reach tailnet-member hosts on VLAN 40 (sandbox01). The forward path works, but replies to the client's100.64.0.0/10source detour into the host's owntailscale0(peer /32 in table 52) and are dropped, because10.10.40.10is not a route that host advertises. Confirmed with tcpdump onsandbox01: echo requests arrive onenp2s0, no replies leave it. Hosts without tailscaled (nas01) are unaffected.Change
New NAT source rule 110: masquerade
100.64.0.0/10outbr40only. Home-to-lab, inter-VLAN, and tailscale traffic to other VLANs keep their source addresses per the address plan.Validation
moon run network:vyos-validatepassesmoon run network:test— 42 passed10.10.40.10verified working pre-change (unaffected by this rule)