[tor-commits] [torspec/master] Prop 312: Add an alternative IPv6 disable design

[teor at torproject.org]

commit 0e20e5a06736a36599e2c1a2e2efd1f055ee18bb
Author: teor <teor at torproject.org>
Date:   Mon Feb 3 19:00:12 2020 +1000

    Prop 312: Add an alternative IPv6 disable design
    
    And explain why we didn't use the existing ORPort IPv4Only flag to
    disable IPv6 address resolution.
    
    Part of 33073.
---
 proposals/312-relay-auto-ipv6-addr.txt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/proposals/312-relay-auto-ipv6-addr.txt b/proposals/312-relay-auto-ipv6-addr.txt
index ec1d52d..3f3b587 100644
--- a/proposals/312-relay-auto-ipv6-addr.txt
+++ b/proposals/312-relay-auto-ipv6-addr.txt
@@ -387,6 +387,21 @@ Ticket: #33073
    resolution, IPv6 ORPorts, IPv6 reachability checks, and publishing an IPv6
    ORPort in its descriptor.
 
+3.2.7.1. Disabling IPv6 Address Resolution: Alternative Design
+
+   As an alternative design, tor could change its interpretation of the
+   IPv4Only flag, so that the following configuration lines disable IPv6:
+   (In the absence of any non-IPv4Only  ORPort lines.)
+     * ORPort 9999 IPv4Only
+     * ORPort 1.1.1.1:9999 IPv4Only
+
+   However, we believe that this is a confusing design, because we want to
+   enable IPv6 address resolution on this similar, very common configuration:
+     * ORPort 1.1.1.1:9999
+
+   Therefore, we avoid this design, becuase it changes the meaning of existing
+   flags and options.
+
 3.2.8. Automatically Enabling an IPv6 ORPort
 
    We propose that relays (and bridges) that discover their IPv6 address,