xref: /freebsd/crypto/openssh/FREEBSD-upgrade (revision 438fd19dc327400e5fbcebfcb9fe9361b317e791)

	    FreeBSD maintainer's guide to OpenSSH-portable
	    ==============================================

    These instructions assume you have a clone of the FreeBSD git repo
    main branch in src/freebsd/main, and will store vendor trees under
    src/freebsd/vendor/.  In addition, this assumes there is a "freebsd"
    origin pointing to git(repo).freebsd.org/src.git.

00) Make sure your mail spool has plenty of free space.  It'll fill up
    pretty fast once you're done with this checklist.

01) Download the latest OpenSSH-portable tarball and signature from
    OpenBSD (https://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/).

02) Verify the signature:

    $ gpg --verify openssh-X.YpZ.tar.gz.asc

03) Unpack the tarball in a suitable directory:

    $ tar xf openssh-X.YpZ.tar.gz

04) Copy to a vendor branch:

    $ cd src/freebsd/main
    $ git worktree add ../vendor/openssh freebsd/vendor/openssh
    $ cd ../vendor/openssh
    $ rsync --archive --delete --exclude=.git /path/to/openssh-X.YpZ/ ./

05) Take care of added / deleted files:

    $ git add -A

06) Commit:

    $ git commit -m "Vendor import of OpenSSH X.YpZ"

07) Tag:

    $ git tag -a -m "Tag OpenSSH X.YpZ" vendor/openssh/X.YpZ

    At this point the vendor branch can be pushed to the FreeBSD repo via:

    $ git push freebsd vendor/openssh

    (It could also be pushed later on, along with the merge to main, but
    pushing now allows others to collaborate.)

08) Check out head and run the pre-merge script, which strips our RCS
    tags from files that have them:

    $ cd src/freebsd/main/crypto/openssh
    $ sh freebsd-pre-merge.sh

09) Merge from the vendor branch:

    $ git subtree merge -P crypto/openssh vendor/openssh

    A number of files have been deleted from FreeBSD's copy of ssh,
    including rendered man pages (which have a .0 extension).  When
    git prompts for these deleted files during the merge, choose 'd'
    (leaving them deleted).

0A) Resolve conflicts.  Remember to bump the version addendum in
    version.h, and update the default value in ssh{,d}_config and
    ssh{,d}_config.5.

0B) Diff against the vendor branch:

    $ git diff --diff-filter=M vendor/openssh/X.YpZ HEAD:crypto/openssh

    Files that have modifications relative to the vendor code, and
    only those files, must have the svn:keywords property set to
    FreeBSD=%H and be listed in the 'keywords' file created by the
    pre-merge script.

0C) Run the post-merge script, which re-adds RCS tags to files that
    need them:

    $ sh freebsd-post-merge.sh

    These tags are not used with git, but we will leave them in place as
    long as svn-based FreeBSD 11.x and 12.x are supported.

0D) Run the configure script:

    $ sh freebsd-configure.sh

0E) Review changes to config.h very carefully.

    Note that libwrap should not be defined in config.h; as of
    r311585 (233932cc2a60) it is conditional on MK_TCP_WRAPPERS.

0F) If source files have been added or removed, update the appropriate
    makefiles to reflect changes in the vendor's Makefile.in.

10) Update ssh_namespace.h:

    $ sh freebsd-namespace.sh

11) Build and install world, reboot, test.  Pay particular attention
    to pam_ssh(8), which gropes inside libssh and will break if
    something significant changes or if ssh_namespace.h is out of
    whack.

12) Update nanobsd's copies of the ssh config files:

    tools/tools/nanobsd/rescue/Files/etc/ssh/ssh_config
    tools/tools/nanobsd/rescue/Files/etc/ssh/sshd_config

13) Commit, and hunker down for the inevitable storm of complaints.



	  An overview of FreeBSD changes to OpenSSH-portable
	  ==================================================

0) VersionAddendum

   The SSH protocol allows for a human-readable version string of up
   to 40 characters to be appended to the protocol version string.
   FreeBSD takes advantage of this to include a date indicating the
   "patch level", so people can easily determine whether their system
   is vulnerable when an OpenSSH advisory goes out.  Some people,
   however, dislike advertising their patch level in the protocol
   handshake, so we've added a VersionAddendum configuration variable
   to allow them to change or disable it.  Upstream added support for
   VersionAddendum on the server side, but we also support it on the
   client side.

1) Modified server-side defaults

   We've modified some configuration defaults in sshd:

      - UsePAM defaults to "yes".
      - PermitRootLogin defaults to "no".
      - X11Forwarding defaults to "yes".
      - PasswordAuthentication defaults to "no".
      - VersionAddendum defaults to "FreeBSD-YYYYMMDD".
      - PrivilegeSeparation defaults to "sandbox".
      - UseDNS defaults to "yes".

2) Modified client-side defaults

   We've modified some configuration defaults in ssh:

      - CheckHostIP defaults to "no".
      - VerifyHostKeyDNS defaults to "yes" if built with LDNS.
      - VersionAddendum defaults to "FreeBSD-YYYYMMDD".

3) Canonic host names

   We've added code to ssh.c to canonicize the target host name after
   reading options but before trying to connect.  This eliminates the
   usual problem with duplicate known_hosts entries.

4) setusercontext() environment

   Our setusercontext(3) can set environment variables, which we must
   take care to transfer to the child's environment.

5) TCP wrappers

   Support for TCP wrappers was removed in upstream 6.7p1.  We've
   added it back by porting the 6.6p1 code forward.

   TCP wrappers support in sshd will be disabled in HEAD and will
   be removed from FreeBSD in the future.

6) Agent client reference counting

   We've added code to ssh-agent.c to implement client reference
   counting; the agent will automatically exit when the last client
   disconnects.

7) Class-based login restrictions (27ceebbc2402)

   We've added code to auth.c to enforce the host.allow, host.deny,
   times.allow and times.deny login class capabilities, based on an
   upstream submission from
   https://github.com/openssh/openssh-portable/pull/262.

8) HPN

   We no longer have the HPN patches (adaptive buffer size for
   increased throughput on high-BxD links), but we recognize and
   ignore HPN-related configuration options to avoid breaking existing
   configurations.



This port was brought to you by (in no particular order) DARPA, NAI
Labs, ThinkSec, Nescafé, the Aberlour Glenlivet Distillery Co.,
Suzanne Vega, and a Sanford's #69 Deluxe Marker.

					-- des@FreeBSD.org

$FreeBSD$