Darren hi Thanks - that assures me that I wasn't missing something obvious. Plus your reasoning makes perfect sense - I was starting to wonder what I'd need to implement client-side to handle if/when I managed to get a PASSWD_CHANGEREQ response - e.g. complexity, dictionary and previous password checks - all of which (as you say) are system specific and should be defined server-side from an admin POV. If the spec was open for input/revision (probably one for others) I might be suggesting that the expiry interchange mechanism should be defined at a more granular level (e.g. number of password user entries, success/fail feedback, max number of retries) As the SSHJ library has session based support, I believe I can add some handling to work with the "passwd" functionality at the command line level, which the SSH session drops into on password expiry. For ref: the SSHJ ticket I raised on this is at https://github.com/hierynomus/sshj/issues/453. Thanks again David -----Original Message----- From: openssh-unix-dev <openssh-unix-dev-bounces+david.hubbard=infracentric.com@xxxxxxxxxxx> On Behalf Of Darren Tucker Sent: 29 September 2018 01:09 To: david.hubbard@xxxxxxxxxxxxxxxx Cc: OpenSSH Devel List <openssh-unix-dev@xxxxxxxxxxx> Subject: Re: Support for RFC4252 in sshd with PAM On Fri, 28 Sep 2018 at 23:34, <david.hubbard@xxxxxxxxxxxxxxxx> wrote: > Looking at RFC4252 <https://www.ietf.org/rfc/rfc4252.txt> (which is > supported by SSHJ) I don't see any SSH_MSG_USERAUTH_PASSWD_CHANGEREQ > [60] messages getting passed from OpenSSH. SSHJ expects these to > allow prompting for new password. > > The only references to SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ in the > OpenSSH Portable code are in "sshconnect2.c" - which I believe is client-side. Correct. The problem is that the semantics of password changing via PASSWD_CHANGEREQ ("here's the old password and new password, make it so") can't be implemented with PAM's interface ("I'll send you arbitrary messages and you send me arbitrary replies until I'm happy"). It is possible using the keyboard-interactive method (RFC4256) and PAM password changing is implemented there. I experimented with various password expiry handling methods in the past and ultimately gave up on PASSWD_CHANGEREQ. There is to my knowledge no standard or common API that can implement the change part (short of implementing everything including things like password history and complexity rules yourself, all of which are system specific). -- Darren Tucker (dtucker at dtucker.net) GPG key 11EAA6FA / A86E 3E07 5B19 5880 E860 37F4 9357 ECEF 11EA A6FA (new) Good judgement comes with experience. Unfortunately, the experience usually comes from bad judgement. _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
