7

OS X System 10.8 if that matters.

I enabled password authentication for the built-in sshd, changing the setting for PasswordAuthentication thus:

# To disable tunneled clear text passwords both PasswordAuthentication and
# ChallengeResponseAuthentication must be set to "no"
PasswordAuthentication yes
PermitEmptyPasswords yes

# Change to no to disable s/key passwords
ChallengeResponseAuthentication yes

This did enable password authentication, but it also seems to have affected keyboard authentication for some reason.

If I try to ssh into the machine (with no options), it hangs forever. If I use ssh -vvv, I can see it's hanging after sending the keyboard-interactive packet:

debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug3: start over, passed a different list publickey,password,keyboard-interactive
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/ucc/coxy/.ssh/id_rsa
debug3: no such identity: /home/ucc/coxy/.ssh/id_rsa
debug1: Trying private key: /home/ucc/coxy/.ssh/id_dsa
debug3: no such identity: /home/ucc/coxy/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug2: we sent a keyboard-interactive packet, wait for reply

And of course if I ssh using ssh -o 'KbdInteractiveDevices no' then I can get in just fine. But I would really prefer to use keyboard-interactive auth where possible, or at least have it fall back more gracefully. What can I do? Is there a way to change the order of the preferred authentication types on my sshd?

Edit: full sshd_config, pretty standard.

#   $OpenBSD: sshd_config,v 1.81 2009/10/08 14:03:41 markus Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options change a
# default value.

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# The default requires explicit activation of protocol 1
#Protocol 2

# HostKey for protocol version 1
#HostKey /etc/ssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key

# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 1024

# Logging
# obsoletes QuietMode and FascistLogging
SyslogFacility AUTHPRIV
LogLevel DEBUG2

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#RSAAuthentication yes
#PubkeyAuthentication yes
#AuthorizedKeysFile .ssh/authorized_keys

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#RhostsRSAAuthentication no
# similar for protocol version 2
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords both PasswordAuthentication and
# ChallengeResponseAuthentication must be set to "no"
PasswordAuthentication yes
PermitEmptyPasswords yes

# Change to no to disable s/key passwords
ChallengeResponseAuthentication yes

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no

# Set this to 'yes' to enable PAM authentication, account processing, 
# and session processing. If this is enabled, PAM authentication will 
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
# Also, PAM will deny null passwords by default.  If you need to allow
# null passwords, add the " nullok" option to the end of the
# securityserver.so line in /etc/pam.d/sshd.
#UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10
#PermitTunnel no
#ChrootDirectory none

# pass locale information
AcceptEnv LANG LC_*

# no default banner path
#Banner none

# override default of no subsystems
Subsystem   sftp    /usr/libexec/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#   X11Forwarding no
#   AllowTcpForwarding no
#   ForceCommand cvs server
7
  • What do the server logs say?
    – mgorven
    Aug 14, 2012 at 0:57
  • nothing I'm afraid. I'll look into changing the verbosity of the sshd logs.
    – Coxy
    Aug 14, 2012 at 1:20
  • For order of authentication, see this post -- serverfault.com/questions/283722/authentication-order-with-ssh
    – Chida
    Aug 14, 2012 at 5:55
  • @Chida, I think you misunderstand slightly, I want to reorder the server not the client. The idea being that I will still be able to connect to the server without remembering the correct command line option to specify, or from cut-down clients like mobile devices.
    – Coxy
    Aug 14, 2012 at 6:19
  • 1
    I'm not sure if that is possible, however could you post your sshd_config?
    – Chida
    Aug 14, 2012 at 6:25

1 Answer 1

2

This appears to have been a bug in sshd that was fixed in System 10.9 Mavericks.

It's still not perfect, as you can see from the verbose logging. It will not use keyboard-interactive authentication for whatever reason. But at least now it falls through to password authentication without specifically being told to.

debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug3: start over, passed a different list publickey,password,keyboard-interactive
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/ucc/coxy/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug1: Trying private key: /home/ucc/coxy/.ssh/id_dsa
debug3: no such identity: /home/ucc/coxy/.ssh/id_dsa
debug1: Trying private key: /home/ucc/coxy/.ssh/id_ecdsa
debug3: no such identity: /home/ucc/coxy/.ssh/id_ecdsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug2: we sent a keyboard-interactive packet, wait for reply
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug3: userauth_kbdint: disable: no info_req_seen
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred:
debug3: authmethod_is_enabled password
debug1: Next authentication method: password

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