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. 01) Make sure your mail spool has plenty of free space. It'll fill up pretty fast once you're done with this checklist. 02) Download the latest OpenSSH-portable tarball and signature from OpenBSD (https://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/). 03) Verify the signature: $ gpg --verify openssh-X.YpZ.tar.gz.asc 04) Unpack the tarball in a suitable directory: $ tar xf openssh-X.YpZ.tar.gz 05) 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/ ./ 06) Take care of added / deleted files: $ git add -A 07) Commit: $ git commit -m "Vendor import of OpenSSH X.YpZ" 08) 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 $ git push freebsd vendor/openssh/X.YpZ Note the second "git push" command is used to push the tag, which is not pushed by default. It is also possible to push the branch and tag together, but use --dry-run first to ensure that no undesired tags will be pushed: $ git push --dry-run --follow-tags freebsd vendor/openssh $ git push --follow-tags freebsd vendor/openssh The update and tag could instead be pushed later, along with the merge to main, but pushing now allows others to collaborate. 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). 10) Resolve conflicts. Remember to bump the version addendum in version.h, and update the default value in sshd_config and sshd_config.5. 11) Diff against the vendor branch: $ git diff --diff-filter=M vendor/openssh/X.YpZ HEAD:crypto/openssh Review the diff for any unexpected changes. 12) Run the configure script: $ cd crypto/openssh $ sh freebsd-configure.sh 13) 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. 14) If source files have been added or removed, update the appropriate makefiles to reflect changes in the vendor's Makefile.in. 15) Update ssh_namespace.h: $ cd crypto/openssh $ sh freebsd-namespace.sh 16) 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. 17) Check for references to obsolete configuration options (e.g., ChallengeResponseAuthentication in sshd_config) which may exist in release/ scripts. 18) Commit, and hunker down for the inevitable storm of complaints. An overview of FreeBSD changes to OpenSSH-portable ================================================== 1) Modified server-side defaults We've modified some configuration defaults in sshd: - UsePAM defaults to "yes". - PermitRootLogin defaults to "no". - PasswordAuthentication defaults to "no". - VersionAddendum defaults to "FreeBSD-YYYYMMDD". - UseDNS defaults to "yes". 2) Modified client-side defaults We defaulted CheckHostIP to "no" in 2000 (a95c1225217b). Upstream has now made the same change, and we no longer have any modified client-side defaults. 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. We added this support in 2002 (r99054 / bf2e2524a2ce). In 2014 upstream introduced CanonicalDomains and related options to serve a similar purpose but they require environment-specific configuration. 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) Blocklist integration We include blocklist (https://github.com/zoulasc/blocklist) in FreeBSD, and ssh is patched to report login failures to it. 9) Paths A number of paths are changed to match FreeBSD's configuration (e.g., using /usr/local/ instead of /uxr/X11R6/). 10) Memory leaks Coverity reported a memory leak for which we proposed a fix in https://reviews.freebsd.org/D37253 and sent to the upstream mailing list at https://lists.mindrot.org/pipermail/openssh-unix-dev/2022-November/040497.html Upstream subsequently fixed only one of the related leaks, so we reverted the partial fix and applied our change. 11) Retired patches We no longer have HPN patches (adaptive buffer size for increased throughput on high-BxD links) or client-side VersionAddendum, but we recognize and ignore the 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