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finotti
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Post subject: [SOLVED] SSH passwordless login stopped working
Posted: 03.12.2015, 14:38
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Joined: 2010-09-12
Posts: 493
Status: Offline
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I've just updated my system and now passworless login with SSH stopped working.
Code:
# apt-cache policy openssh-client
openssh-client:
Installed: 1:7.1p1-1
Candidate: 1:7.1p1-1
Version table:
*** 1:7.1p1-1 500
500 http://httpredir.debian.org/debian sid/main amd64 Packages
100 /var/lib/dpkg/status
1:6.9p1-3 500
500 http://http.debian.net/debian testing/main amd64 Packages
Version 1:6.9p1-3, running on my home desktop, works.
If anyone knows a fix (other than waiting for a new updated), I'd appreciate it. |
Last edited by finotti on 03.12.2015, 14:49; edited 1 time in total
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finotti
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Post subject: RE: SSH passwordless login stopped working
Posted: 03.12.2015, 14:49
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Joined: 2010-09-12
Posts: 493
Status: Offline
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OK more info.
Code:
$ ssh -v desk
[...]
debug1: Skipping ssh-dss key /home/finotti/.ssh/id_dsa for not in PubkeyAcceptedKeyTypes
[...]
So, maybe DSA keys are now considered insecure?
Adding
Code:
PubkeyAcceptedKeyTypes ssh-dss
to .ssh/config fixes it, but maybe it would be better to change the keys... (Can someone confirm this?)
EDIT: FYI, RSA keys work. |
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peekaboo
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Post subject: RE: SSH passwordless login stopped working
Posted: 05.12.2015, 20:22
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Joined: 2015-12-05
Posts: 1
Location: Germay
Status: Offline
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Hi,
According to bettercrypto.org, DSA should not be used anymore for SSH. See chapter 2.2 Applied Crypto Hardening Paper at » https://bettercrypto.org/ «.
So it's likely DSA has been removed completely now starting with OpenSSH 7.
Regards! |
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slh
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Post subject: RE: SSH passwordless login stopped working
Posted: 05.12.2015, 21:49
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Joined: 2010-08-25
Posts: 962
Status: Offline
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Just to end (part of-) the speculation, have a look at the package changelog (/usr/share/doc/openssh-server/changelog.Debian.gz):
Code:
openssh (1:7.1p1-1) unstable; urgency=medium
* New upstream release (http://www.openssh.com/txt/release-7.0, closes:
#785190):
- Support for the legacy SSH version 1 protocol is disabled by default
at compile time.
- Support for the 1024-bit diffie-hellman-group1-sha1 key exchange is
disabled by default at run-time. It may be re-enabled using the
instructions at http://www.openssh.com/legacy.html
- Support for ssh-dss, ssh-dss-cert-* host and user keys is disabled by
default at run-time. These may be re-enabled using the instructions
at http://www.openssh.com/legacy.html
- Support for the legacy v00 cert format has been removed.
- The default for the sshd_config(5) PermitRootLogin option has changed
from "yes" to "prohibit-password".
- PermitRootLogin=without-password/prohibit-password now bans all
interactive authentication methods, allowing only public-key,
hostbased and GSSAPI authentication (previously it permitted
keyboard-interactive and password-less authentication if those were
enabled).
- ssh_config(5): Add PubkeyAcceptedKeyTypes option to control which
public key types are available for user authentication.
- sshd_config(5): Add HostKeyAlgorithms option to control which public
key types are offered for host authentications.
- ssh(1), sshd(8): Extend Ciphers, MACs, KexAlgorithms,
HostKeyAlgorithms, PubkeyAcceptedKeyTypes and HostbasedKeyTypes
options to allow appending to the default set of algorithms instead of
replacing it. Options may now be prefixed with a '+' to append to the
default, e.g. "HostKeyAlgorithms=+ssh-dss".
- sshd_config(5): PermitRootLogin now accepts an argument of
'prohibit-password' as a less-ambiguous synonym of 'without-
password'.
- ssh(1), sshd(8): Add compatability workarounds for Cisco and more
PuTTY versions.
- Fix some omissions and errors in the PROTOCOL and PROTOCOL.mux
documentation relating to Unix domain socket forwarding.
- ssh(1): Improve the ssh(1) manual page to include a better description
of Unix domain socket forwarding (closes: #779068).
- ssh(1), ssh-agent(1): Skip uninitialised PKCS#11 slots, fixing
failures to load keys when they are present.
- ssh(1), ssh-agent(1): Do not ignore PKCS#11 hosted keys that wth empty
CKA_ID.
- sshd(8): Clarify documentation for UseDNS option.
- Check realpath(3) behaviour matches what sftp-server requires and use
a replacement if necessary.
* New upstream release (http://www.openssh.com/txt/release-7.1):
- sshd(8): OpenSSH 7.0 contained a logic error in PermitRootLogin=
prohibit-password/without-password that could, depending on
compile-time configuration, permit password authentication to root
while preventing other forms of authentication. This problem was
reported by Mantas Mikulenas.
- ssh(1), sshd(8): Add compatibility workarounds for FuTTY.
- ssh(1), sshd(8): Refine compatibility workarounds for WinSCP.
- Fix a number of memory faults (double-free, free of uninitialised
memory, etc) in ssh(1) and ssh-keygen(1). Reported by Mateusz
Kocielski.
* Change "PermitRootLogin without-password" to the new preferred spelling
of "PermitRootLogin prohibit-password" in sshd_config, and update
documentation to reflect the new upstream default.
* Enable conch interoperability tests under autopkgtest.
-- Colin Watson <xxx> Wed, 02 Dec 2015 20:18:35 +0000
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finotti
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Post subject: RE: SSH passwordless login stopped working
Posted: 06.12.2015, 13:43
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Joined: 2010-09-12
Posts: 493
Status: Offline
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Thanks for confirming it! I've changed my keys to RSA. |
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Lat
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Post subject: RE: SSH passwordless login stopped working
Posted: 06.12.2015, 15:55
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Joined: 2010-09-19
Posts: 205
Status: Offline
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How do I check if I have DSA, and how do I convert it RSA? |
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slh
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Post subject: RE: SSH passwordless login stopped working
Posted: 06.12.2015, 23:35
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Joined: 2010-08-25
Posts: 962
Status: Offline
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Look into the key-files under ~/.ssh/, you'll see "-----BEGIN RSA PRIVATE KEY-----" or "ssh-rsa" for the public key, compared to "-----BEGIN DSA PRIVATE KEY-----" or "ssh-dss" respectively; most of the time, the key naming will also tell you. |
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Lat
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Post subject: RE: SSH passwordless login stopped working
Posted: 12.12.2015, 11:41
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Joined: 2010-09-19
Posts: 205
Status: Offline
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