On Jan 10, 2011, at 5:36 PM, Garance A Drosihn wrote:

> On 1/8/11 4:33 PM, Levan, Jerry wrote:
>> Grumble,
>> 
>> sshd_config lies...
>> 
>> Checking the security log shows that ssh is using PAM even
>> though sshd_config had
>> 
>> #UsePAM no
>> 
>> I had to uncomment the above line and reboot to get
>> password authentication killed.
>> 
>> ....Hold the phone...
>> I just checked another one of my macs and the sshd_config file
>> is *different* from the one on the server! They are running the
>> same OS version and level.
>> 
>> My other mac has
>> #UsePAM yes
>> and more discussion prior to the directive.
> 
> Note that the distributed sshd_config really is just a file
> of comments.  The comments are supposed to match what options
> are compiled into that version of sshd, but there's nothing
> to make sure that the comments match the binary.
> 
> Thus it isn't too surprising that some comments might not
> match the version of sshd which is running.

All true, but no reason why a sysadmin should complain of sshd "lying". It's a 
simple matter to just perform a `sshd -T` and see exactly what is and isn't 
configured. A sysadmin should be expected to read the man page at least, 
especially if it's not behaving as they expect. Blaming software for your own 
errors isn't helpful.

Running `sshd -T` on one of my OSXS systems (which may not match yours) reveals:

Could not load host key: /etc/ssh_host_rsa_key
Could not load host key: /etc/ssh_host_dsa_key
port 22
protocol 2
addressfamily any
listenaddress [::]:22
listenaddress 0.0.0.0:22
usepam 1
serverkeybits 1024
logingracetime 120
keyregenerationinterval 3600
x11displayoffset 10
maxauthtries 6
maxsessions 10
clientaliveinterval 0
clientalivecountmax 3
permitrootlogin yes
ignorerhosts yes
ignoreuserknownhosts no
rhostsrsaauthentication no
hostbasedauthentication no
hostbasedusesnamefrompacketonly no
rsaauthentication yes
pubkeyauthentication yes
kerberosauthentication yes
kerberosorlocalpasswd yes
kerberosticketcleanup yes
gssapiauthentication yes
gssapicleanupcredentials yes
passwordauthentication no
kbdinteractiveauthentication yes
challengeresponseauthentication yes
printmotd yes
printlastlog yes
x11forwarding no
x11uselocalhost yes
strictmodes yes
tcpkeepalive yes
permitemptypasswords no
permituserenvironment no
uselogin no
compression delayed
gatewayports no
usedns yes
allowtcpforwarding yes
useprivilegeseparation yes
pidfile /var/run/sshd.pid
xauthlocation /usr/X11R6/bin/xauth
authorizedkeysfile .ssh/authorized_keys
authorizedkeysfile2 .ssh/authorized_keys2
loglevel INFO
syslogfacility AUTHPRIV
hostkey /etc/ssh_host_rsa_key
hostkey /etc/ssh_host_dsa_key
subsystem sftp /usr/libexec/sftp-server
maxstartups 10:100:10
permittunnel no
permitopen any

Which would indicate there would be a lot of authentication types that would 
need disabled other than just PAM and passwordauthentication if you wanted to 
just have keys only enabled. 

And configuring this system wide may not be a good idea as it could lock out 
other functions (such as Open Directory master/slave operations). It would be 
better to configure for specific users accordingly. 

I'd strongly suggest the original poster review the sshd and ssh docs found in 
the man pages, online at openssh.com and, since it seems there's a lot being 
missed in expected behavior, I'd also highly suggest reading the "snail book" 
from O'Reilly. You can get a trial subscription to their excellent Safari 
Online Book Service and have the opportunity to read it in depth during the 
trial. Click the link on the page below. 

http://oreilly.com/catalog/9780596008956

-d

------------------------------------------------------------------------
Dan Shoop
[email protected]
GoogleVoice: 1-646-402-5293
aim: iWiring
twitter: @colonelmode



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