We introduced hostname canonicalization in 2002, while upstream OpenSSH added similar support in 2014. It would be good to review our handling of CNAMEs in hostname canonicalization. Sponsored by: The FreeBSD Foundation
187 lines
5.9 KiB
Plaintext
187 lines
5.9 KiB
Plaintext
FreeBSD maintainer's guide to OpenSSH-portable
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==============================================
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These instructions assume you have a clone of the FreeBSD git repo
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main branch in src/freebsd/main, and will store vendor trees under
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src/freebsd/vendor/. In addition, this assumes there is a "freebsd"
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origin pointing to git(repo).freebsd.org/src.git.
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01) Make sure your mail spool has plenty of free space. It'll fill up
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pretty fast once you're done with this checklist.
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02) Download the latest OpenSSH-portable tarball and signature from
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OpenBSD (https://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/).
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03) Verify the signature:
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$ gpg --verify openssh-X.YpZ.tar.gz.asc
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04) Unpack the tarball in a suitable directory:
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$ tar xf openssh-X.YpZ.tar.gz
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05) Copy to a vendor branch:
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$ cd src/freebsd/main
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$ git worktree add ../vendor/openssh freebsd/vendor/openssh
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$ cd ../vendor/openssh
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$ rsync --archive --delete --exclude=.git /path/to/openssh-X.YpZ/ ./
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06) Take care of added / deleted files:
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$ git add -A
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07) Commit:
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$ git commit -m "Vendor import of OpenSSH X.YpZ"
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08) Tag:
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$ git tag -a -m "Tag OpenSSH X.YpZ" vendor/openssh/X.YpZ
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At this point the vendor branch can be pushed to the FreeBSD repo via:
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$ git push freebsd vendor/openssh
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$ git push freebsd vendor/openssh/X.YpZ
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Note the second "git push" command is used to push the tag, which is
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not pushed by default.
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It is also possible to push the branch and tag together, but use
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--dry-run first to ensure that no undesired tags will be pushed:
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$ git push --dry-run --follow-tags freebsd vendor/openssh
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$ git push --follow-tags freebsd vendor/openssh
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The update and tag could instead be pushed later, along with the merge
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to main, but pushing now allows others to collaborate.
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09) Merge from the vendor branch:
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$ git subtree merge -P crypto/openssh vendor/openssh
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A number of files have been deleted from FreeBSD's copy of ssh,
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including rendered man pages (which have a .0 extension). When
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git prompts for these deleted files during the merge, choose 'd'
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(leaving them deleted).
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10) Resolve conflicts. Remember to bump the version addendum in
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version.h, and update the default value in sshd_config and
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sshd_config.5.
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11) Diff against the vendor branch:
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$ git diff --diff-filter=M vendor/openssh/X.YpZ HEAD:crypto/openssh
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Review the diff for any unexpected changes.
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12) Run the configure script:
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$ sh freebsd-configure.sh
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13) Review changes to config.h very carefully.
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Note that libwrap should not be defined in config.h; as of
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r311585 (233932cc2a60) it is conditional on MK_TCP_WRAPPERS.
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14) If source files have been added or removed, update the appropriate
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makefiles to reflect changes in the vendor's Makefile.in.
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15) Update ssh_namespace.h:
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$ sh freebsd-namespace.sh
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16) Build and install world, reboot, test. Pay particular attention
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to pam_ssh(8), which gropes inside libssh and will break if
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something significant changes or if ssh_namespace.h is out of
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whack.
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17) Check for references to obsolete configuration options
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(e.g., ChallengeResponseAuthentication in sshd_config) which
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may exist in release/ scripts.
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18) Commit, and hunker down for the inevitable storm of complaints.
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An overview of FreeBSD changes to OpenSSH-portable
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==================================================
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1) Modified server-side defaults
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We've modified some configuration defaults in sshd:
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- UsePAM defaults to "yes".
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- PermitRootLogin defaults to "no".
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- PasswordAuthentication defaults to "no".
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- VersionAddendum defaults to "FreeBSD-YYYYMMDD".
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- UseDNS defaults to "yes".
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2) Modified client-side defaults
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We've modified some configuration defaults in ssh:
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- CheckHostIP defaults to "no".
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- VerifyHostKeyDNS defaults to "yes" if built with LDNS.
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3) Canonic host names
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We've added code to ssh.c to canonicize the target host name after
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reading options but before trying to connect. This eliminates the
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usual problem with duplicate known_hosts entries.
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We added this support in 2002 (r99054 / bf2e2524a2ce). In 2014
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upstream introduced CanonicalDomains and related options to serve a
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similar purpose but they require environment-specific configuration.
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4) setusercontext() environment
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Our setusercontext(3) can set environment variables, which we must
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take care to transfer to the child's environment.
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5) TCP wrappers
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Support for TCP wrappers was removed in upstream 6.7p1. We've
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added it back by porting the 6.6p1 code forward.
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TCP wrappers support in sshd will be disabled in HEAD and will
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be removed from FreeBSD in the future.
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6) Agent client reference counting
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We've added code to ssh-agent.c to implement client reference
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counting; the agent will automatically exit when the last client
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disconnects.
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7) Class-based login restrictions (27ceebbc2402)
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We've added code to auth.c to enforce the host.allow, host.deny,
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times.allow and times.deny login class capabilities, based on an
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upstream submission from
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https://github.com/openssh/openssh-portable/pull/262.
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8) Blocklist integration
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We include blocklist (https://github.com/zoulasc/blocklist) in FreeBSD,
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and ssh is patched to report login failures to it.
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9) Paths
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A number of paths are changed to match FreeBSD's configuration (e.g.,
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using /usr/local/ instead of /uxr/X11R6/).
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10) Retired patches
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We no longer have HPN patches (adaptive buffer size for increased
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throughput on high-BxD links) or client-side VersionAddendum, but we
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recognize and ignore the configuration options to avoid breaking
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existing configurations.
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This port was brought to you by (in no particular order) DARPA, NAI
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Labs, ThinkSec, Nescafé, the Aberlour Glenlivet Distillery Co.,
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Suzanne Vega, and a Sanford's #69 Deluxe Marker.
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-- des@FreeBSD.org
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