Improve docs.

1 files changed, 7 insertions, 1 deletions

diff --git a/lacme.md b/lacme.md
index 7f2e616..3ba4a44 100644
--- a/lacme.md
+++ b/lacme.md
@@ -224,7 +224,7 @@ of [ACME] commands and dialogues with the remote [ACME] server).
 ---------------------
 
 This section is used to configure how [ACME] challenge responses are
-served.
+served during certificate issuance.
 
 *listen*
 
@@ -232,6 +232,12 @@ served.
     addresses are of the form `IPV4:PORT`, `[IPV6]:PORT` (where the
     `:PORT` suffix is optional and defaults to the HTTP port 80), or an
     absolute path of a UNIX-domain socket (created with mode `0666`).
+    Since the webserver component listens to a UNIX-domain socket by
+    default, it is only suitable when an external HTTP daemon is
+    publicly reachable and passes all ACME challenge requests to that
+    socket; if that's not the case, one needs to set *listen* to `[::]`
+    (or `0.0.0.0 [::]` when dual stack IPv4/IPv6 is disabled or
+    unavailable), and possibly also set *iptables* to `Yes`.
     Default: `/var/run/lacme.socket`.
 
 *challenge-directory*