When listing listening sockets using 'ss -nlpe', there is no indication about whether an AF_INET6 socket is dual-stack capable, i.e. allows access from IPv4 as well. The following upstream patch solves this issue:
Author: Phil Sutter <email@example.com>
Date: Wed Jun 24 13:07:20 2015 +0200
ss: print value of IPV6_V6ONLY socket option if set
If available and set, print 'v6only:1' for AF_INET6 sockets upon request
of extended information. For IPv6 sockets bound to in6addr_any, this is
the only way to determine if they will also accept IPv4 requests or not.
Signed-off-by: Phil Sutter <firstname.lastname@example.org>
*** Bug 1244313 has been marked as a duplicate of this bug. ***
Fixed in version 3.10.0-48.el7:
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.