Na}{

File Content: `README.privsep`

Privilege separation, or privsep, is method in OpenSSH by which
operations that require root privilege are performed by a separate
privileged monitor process.  Its purpose is to prevent privilege
escalation by containing corruption to an unprivileged process.
More information is available at:
	http://www.citi.umich.edu/u/provos/ssh/privsep.html

Privilege separation is now enabled by default; see the
UsePrivilegeSeparation option in sshd_config(5).

When privsep is enabled, during the pre-authentication phase sshd will
chroot(2) to "/var/empty" and change its privileges to the "sshd" user
and its primary group.  sshd is a pseudo-account that should not be
used by other daemons, and must be locked and should contain a
"nologin" or invalid shell.

You should do something like the following to prepare the privsep
preauth environment:

	# mkdir /var/empty
	# chown root:sys /var/empty
	# chmod 755 /var/empty
	# groupadd sshd
	# useradd -g sshd -c 'sshd privsep' -d /var/empty -s /bin/false sshd

/var/empty should not contain any files.

configure supports the following options to change the default
privsep user and chroot directory:

  --with-privsep-path=xxx Path for privilege separation chroot
  --with-privsep-user=user Specify non-privileged user for privilege separation

PAM-enabled OpenSSH is known to function with privsep on AIX, FreeBSD, 
HP-UX (including Trusted Mode), Linux, NetBSD and Solaris.

On Cygwin, Tru64 Unix and OpenServer only the pre-authentication part
of privsep is supported.  Post-authentication privsep is disabled
automatically (so you won't see the additional process mentioned below).

Note that for a normal interactive login with a shell, enabling privsep
will require 1 additional process per login session.

Given the following process listing (from HP-UX):

     UID   PID  PPID  C    STIME TTY       TIME COMMAND
    root  1005     1  0 10:45:17 ?         0:08 /opt/openssh/sbin/sshd -u0
    root  6917  1005  0 15:19:16 ?         0:00 sshd: stevesk [priv]
 stevesk  6919  6917  0 15:19:17 ?         0:03 sshd: stevesk@2
 stevesk  6921  6919  0 15:19:17 pts/2     0:00 -bash

process 1005 is the sshd process listening for new connections.
process 6917 is the privileged monitor process, 6919 is the user owned
sshd process and 6921 is the shell process.

Name	Size	Permission
CREDITS	5493 bytes	0644
ChangeLog	331065 bytes	0644
INSTALL	9239 bytes	0644
OVERVIEW	6333 bytes	0644
PROTOCOL	19775 bytes	0644
PROTOCOL.agent	220 bytes	0644
PROTOCOL.certkeys	12231 bytes	0644
PROTOCOL.chacha20poly1305	4626 bytes	0644
PROTOCOL.cve-2023-48795	18433 bytes	0644
PROTOCOL.key	1539 bytes	0644
PROTOCOL.krl	5254 bytes	0644
PROTOCOL.mux	9079 bytes	0644
README	2451 bytes	0644
README.dns	1607 bytes	0644
README.platform	4046 bytes	0644
README.privsep	2307 bytes	0644
README.tun	4890 bytes	0644
TODO	2600 bytes	0644

File Content: README.privsep

File Content: `README.privsep`