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wswartzendruber
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Joined: 23 Mar 2004
Posts: 1261
Location: Idaho, USA
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 Posted: Wed Jan 02, 2008 6:49 pm Post subject: Is This sshd_config Secure? |
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I want to secure my box against people logging in with passwords. I want it so that my private keyfile and that one alone are required to gain access.
/etc/ssh/sshd_config
| Code: | # $OpenBSD: sshd_config,v 1.75 2007/03/19 01:01:29 djm 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 ::
# Disable legacy (protocol version 1) support in the server for new
# installations. In future the default will change to require 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 768
# Logging
# obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#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, change to no here!
PasswordAuthentication no
#PermitEmptyPasswords no
# Change to no to disable s/key passwords
ChallengeResponseAuthentication no
# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
# 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'.
UsePAM 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
# no default banner path
#Banner /some/path
# override default of no subsystems
Subsystem sftp /usr/lib/misc/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
# X11Forwarding no
# AllowTcpForwarding no
# ForceCommand cvs server |
Now my username on my client is wswartzendruber. Does this keyfile work for any username I try to login as, or just root?
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gerdesj
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Joined: 29 Sep 2005
Posts: 622
Location: Yeovil, Somerset, UK
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| Posted: Wed Jan 02, 2008 10:59 pm Post subject: |
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Have you actually tried it?
Cheers
Jon |
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wswartzendruber
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Joined: 23 Mar 2004
Posts: 1261
Location: Idaho, USA
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| Posted: Thu Jan 03, 2008 5:09 am Post subject: |
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Yeah, but I'm not too knowledgable of SSHD. Also, I'm wondering what all accounts I can login to the server with using that keyfile.
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gerdesj
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Joined: 29 Sep 2005
Posts: 622
Location: Yeovil, Somerset, UK
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| Posted: Thu Jan 03, 2008 10:58 am Post subject: |
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| wswartzendruber wrote: | | Yeah, but I'm not too knowledgable of SSHD. Also, I'm wondering what all accounts I can login to the server with using that keyfile. |
Fair enough. I believe that the keyfile will only work for those user accounts that have the corresponding bit in their .ssh/authorized_keys file.
I've just had a look here:
http://www.openbsd.org/cgi-bin/man.cgi?query=sshd_config&sektion=5&arch=&apropos=0&manpath=OpenBSD+Current
It seems that RSAAuthentication is for version 1 only so I would set that to no, although you already have v1 disabled.
You have PubKey only enabled as far as I can see, so yes, I believe the config will work as you want it to. You might want to set IgnoreUserKnownHosts = yes. That will stop people creating known hosts and bypassing your keyfile.
Cheers
Jon |
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