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✏️ Editing: README.platform

This file contains notes about OpenSSH on specific platforms.

AIX
---
As of OpenSSH 3.8p1, sshd will now honour an accounts password expiry
settings, where previously it did not.  Because of this, it's possible for
sites that have used OpenSSH's sshd exclusively to have accounts which
have passwords expired longer than the inactive time (ie the "Weeks between
password EXPIRATION and LOCKOUT" setting in SMIT or the maxexpired
chuser attribute).

Accounts in this state must have their passwords reset manually by the
administrator.  As a precaution, it is recommended that the administrative
passwords be reset before upgrading from OpenSSH <3.8.

As of OpenSSH 4.0, configure will attempt to detect if your version
and maintenance level of AIX has a working getaddrinfo, and will use it
if found.  This will enable IPv6 support.  If for some reason configure
gets it wrong, or if you want to build binaries to work on earlier MLs
than the build host then you can add "-DBROKEN_GETADDRINFO" to CFLAGS
to force the previous IPv4-only behaviour.

IPv6 known to work: 5.1ML7 5.2ML2 5.2ML5
IPv6 known broken: 4.3.3ML11 5.1ML4

If you wish to use dynamic libraries that aren't in the normal system
locations (eg IBM's OpenSSL and zlib packages) then you will need to
define the environment variable blibpath before running configure, eg

blibpath=/lib:/usr/lib:/opt/freeware/lib ./configure \
  --with-ssl-dir=/opt/freeware --with-zlib=/opt/freeware

If sshd is built with the WITH_AIXAUTHENTICATE option (which is enabled
by default) then sshd checks that users are permitted via the
loginrestrictions() function, in particular that the user has the
"rlogin" attribute set.  This check is not done for the root account,
instead the PermitRootLogin setting in sshd_config is used.

If you are using the IBM compiler you probably want to use CC=xlc rather
than the default of cc.

Cygwin
------
To build on Cygwin, OpenSSH requires the following packages:
gcc, gcc-mingw-core, mingw-runtime, binutils, make, openssl,
openssl-devel, zlib, minres, minires-devel.

Darwin and MacOS X
------------------
Darwin does not provide a tun(4) driver required for OpenSSH-based
virtual private networks. The BSD manpage still exists, but the driver
has been removed in recent releases of Darwin and MacOS X.

Nevertheless, tunnel support is known to work with Darwin 8 and
MacOS X 10.4 in Point-to-Point (Layer 3) and Ethernet (Layer 2) mode
using a third party driver. More information is available at:
	http://www-user.rhrk.uni-kl.de/~nissler/tuntap/

Linux
-----

Some Linux distributions (including Red Hat/Fedora/CentOS) include
headers and library links in the -devel RPMs rather than the main
binary RPMs. If you get an error about headers, or complaining about a
missing prerequisite then you may need to install the equivalent
development packages.  On Redhat based distros these may be openssl-devel,
zlib-devel and pam-devel, on Debian based distros these may be
libssl-dev, libz-dev and libpam-dev.

Solaris
-------
If you enable BSM auditing on Solaris, you need to update audit_event(4)
for praudit(1m) to give sensible output.  The following line needs to be
added to /etc/security/audit_event:

32800:AUE_openssh:OpenSSH login:lo

The BSM audit event range available for third party TCB applications is
32768 - 65535.  Event number 32800 has been chosen for AUE_openssh.
There is no official registry of 3rd party event numbers, so if this
number is already in use on your system, you may change it at build time
by configure'ing --with-cflags=-DAUE_openssh=32801 then rebuilding.

Platforms using PAM
-------------------
As of OpenSSH 4.3p1, sshd will no longer check /etc/nologin itself when
PAM is enabled.  To maintain existing behaviour, pam_nologin should be
added to sshd's session stack which will prevent users from starting shell
sessions.  Alternatively, pam_nologin can be added to either the auth or
account stacks which will prevent authentication entirely, but will still
return the output from pam_nologin to the client.

MR SKB