Opened 2 months ago

Closed 5 weeks ago

#15617 closed enhancement (fixed)


Reported by: Bruce Dubbs Owned by: Douglas R. Reno
Priority: normal Milestone: 11.1
Component: BOOK Version: git
Severity: normal Keywords:


New minor version.

Change History (7)

comment:1 by Douglas R. Reno, 2 months ago

Owner: changed from blfs-book to Douglas R. Reno
Status: newassigned

Grab this set of tickets.

comment:2 by Douglas R. Reno, 5 weeks ago

OpenSSH 8.8 was released on 2021-09-26. It is available from the
mirrors listed at
OpenSSH is a 100% complete SSH protocol 2.0 implementation and
includes sftp client and server support.

Once again, we would like to thank the OpenSSH community for their
continued support of the project, especially those who contributed
code or patches, reported bugs, tested snapshots or donated to the
project. More information on donations may be found at:

Future deprecation notice

A near-future release of OpenSSH will switch scp(1) from using the
legacy scp/rcp protocol to using SFTP by default.

Legacy scp/rcp performs wildcard expansion of remote filenames (e.g.
"scp host:* .") through the remote shell. This has the side effect of
requiring double quoting of shell meta-characters in file names
included on scp(1) command-lines, otherwise they could be interpreted
as shell commands on the remote side.

This creates one area of potential incompatibility: scp(1) when using
the SFTP protocol no longer requires this finicky and brittle quoting,
and attempts to use it may cause transfers to fail. We consider the
removal of the need for double-quoting shell characters in file names
to be a benefit and do not intend to introduce bug- compatibility for
legacy scp/rcp in scp(1) when using the SFTP protocol.

Another area of potential incompatibility relates to the use of remote
paths relative to other user's home directories, for example -
"scp host:~user/file /tmp". The SFTP protocol has no native way to
expand a ~user path. However, sftp-server(8) in OpenSSH 8.7 and later
support a protocol extension "" to support


sshd(8) from OpenSSH 6.2 through 8.7 failed to correctly initialise
supplemental groups when executing an AuthorizedKeysCommand or
AuthorizedPrincipalsCommand, where a AuthorizedKeysCommandUser or
AuthorizedPrincipalsCommandUser directive has been set to run the
command as a different user. Instead these commands would inherit
the groups that sshd(8) was started with.

Depending on system configuration, inherited groups may allow
AuthorizedKeysCommand/AuthorizedPrincipalsCommand helper programs to
gain unintended privilege.

Neither AuthorizedKeysCommand nor AuthorizedPrincipalsCommand are
enabled by default in sshd_config(5).

Potentially-incompatible changes

This release disables RSA signatures using the SHA-1 hash algorithm
by default. This change has been made as the SHA-1 hash algorithm is
cryptographically broken, and it is possible to create chosen-prefix
hash collisions for <USD$50K [1]

For most users, this change should be invisible and there is
no need to replace ssh-rsa keys. OpenSSH has supported RFC8332
RSA/SHA-256/512 signatures since release 7.2 and existing ssh-rsa keys
will automatically use the stronger algorithm where possible.

Incompatibility is more likely when connecting to older SSH
implementations that have not been upgraded or have not closely tracked
improvements in the SSH protocol. For these cases, it may be necessary
to selectively re-enable RSA/SHA1 to allow connection and/or user
authentication via the HostkeyAlgorithms and PubkeyAcceptedAlgorithms
options. For example, the following stanza in ~/.ssh/config will enable
RSA/SHA1 for host and user authentication for a single destination host:

    Host old-host
        HostkeyAlgorithms +ssh-rsa
	PubkeyAcceptedAlgorithms +ssh-rsa

We recommend enabling RSA/SHA1 only as a stopgap measure until legacy
implementations can be upgraded or reconfigured with another key type
(such as ECDSA or Ed25519).

[1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
    Application to the PGP Web of Trust" Leurent, G and Peyrin, T

Changes since OpenSSH 8.7

This release is motivated primarily by the above deprecation and
security fix.

New features
 * ssh(1): allow the ssh_config(5) CanonicalizePermittedCNAMEs
   directive to accept a "none" argument to specify the default


 * scp(1): when using the SFTP protocol, continue transferring files
   after a transfer error occurs, better matching original scp/rcp
 * ssh(1): fixed a number of memory leaks in multiplexing,

 * ssh-keygen(1): avoid crash when using the -Y find-principals

 * A number of documentation and manual improvements, including
   bz#3340, PR139, PR215, PR241, PR257


 * ssh-agent(1): on FreeBSD, use procctl to disable ptrace(2)

 * ssh(1)/sshd(8): some fixes to the pselect(2) replacement
   compatibility code. bz#3345

comment:3 by Douglas R. Reno, 5 weeks ago

I'll also make sure to update the ssh-askpass page

comment:4 by Douglas R. Reno, 5 weeks ago

When running the test suite, the 'conch ciphers' tests fail. These appear to be specific to the PuTTY client and are not normally enabled by default (according to regress/Makefile). In other words, they're not supposed to be run on an LFS system. :)

I'm trying the tests again with "sed -i 's/conch-ciphers' regress/Makefile". We'll see how that goes!

comment:5 by Douglas R. Reno, 5 weeks ago

There are supposed to be to '/' there, but Trac took it as a formatting symbol.

comment:6 by Douglas R. Reno, 5 weeks ago

The tests worked fine with the sed.

comment:7 by Douglas R. Reno, 5 weeks ago

Resolution: fixed
Status: assignedclosed
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