doc: name resolution clarification

Sometimes there are users who wonder about when name resolutions/DNS
queries are done, so let's add that for completeness.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

1 files changed, 5 insertions, 3 deletions

diff --git a/iptables.8.in b/iptables.8.in
index 928f46a9..d29deb2e 100644
--- a/iptables.8.in
+++ b/iptables.8.in
@@ -239,9 +239,11 @@ option is omitted.
 .TP
 [\fB!\fP] \fB\-s\fP, \fB\-\-source\fP \fIaddress\fP[\fB/\fP\fImask\fP][\fB,\fP\fI...\fP]
 Source specification. \fIAddress\fP
-can be either a network name, a hostname (please note that specifying
-any name to be resolved with a remote query such as DNS is a really bad idea),
-a network IP address (with \fB/\fP\fImask\fP), or a plain IP address.
+can be either a network name, a hostname, a network IP address (with
+\fB/\fP\fImask\fP), or a plain IP address. Hostnames will
+be resolved once only, before the rule is submitted to the kernel.
+Please note that specifying any name to be resolved with a remote query such as
+DNS is a really bad idea.
 The \fImask\fP
 can be either a network mask or a plain number,
 specifying the number of 1's at the left side of the network mask.