Re: Initial patch to implement partial auth with SSH2

Re: Initial patch to implement partial auth with SSH2

[Karl M]

Hi All...

I am currently running OpenSSH 2.5.2p2 with multiple (sequential) 
authentication modes in a WinNT/Win2k srvany sshd server environment. That 
is: to login, I first type a passphrase for my ssh2 rsa (or dsa) key, then I 
type the password on the local machine. It is working great and gives the 
security improvement I was looking for.

For now, the recipe is as follows:

1) Download and install the latest CygWin code (including source for both 
openssh and openssl).

2) Download Carson Gaspar's 3-28-01 patch from the OpenSSH Archives.

3) cd /openssh-2.5.2p2

4) ./configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/sbin

5) edit defines.h, line 439 and uncomment the `#define USE_PIPES 1'

6) apply the Partial Authentication Patch

7) edit auth2.c, comment out the call to check_nt_auth at the end of 
userauth_pubkey

8) make

9) copy sshd.exe to /usr/sbin (stopping the sshd service as needed)

10) edit /etc/sshd_config, change Protocol whatever line to 'Protocol 2', 
change StrictModes from yes to no, and add the following line near the 
bottom of the file 'AuthOrder2 publickey:password'

You can now run the service from LocalSystem and have rsa/dsa authentication 
from multiple users. The login sequence will now look like:

user@machine ~
$ ssh localhost
Enter passphrase for key '/home/user/.ssh/id_rsa':
Authenticated with partial success.
user@localhost's password:
Last login: Mon Apr 23 00:07:17 2001 from machine

user@machine ~
$

I hope this is helpful.

Thanks,

...Karl
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Re: Initial patch to implement partial auth with SSH2

[Karl M]

Hi Corinna...

I was thinking...for the CygWin environment (on WinNT and Win2k) we could 
avoid the problem of where to place a new call to check_nt_auth and 
auth_password by requiring that if the ssh and sshd user-ids are different, 
that password authentication is required (which was the reason I was 
interested in this in the first place). I can do that for now by using

Authorder2 publickey:password

and commenting out the check in userauth_publickey.

Thanks,

...Karl


>From: Corinna Vinschen <vinschen@redhat.com>
>To: cygwin@cygwin.com, openssh-unix-dev@mindrot.org
>Subject: Re: Initial patch to implement partial auth with SSH2
>Date: Fri, 20 Apr 2001 13:13:54 +0200
>
>On Fri, Apr 20, 2001 at 01:29:42AM -0700, Karl M wrote:
> > Hi All...
> >
> > I've been experimenting with the partial authorization patch for
> > OpenSSH-2.5.2. I'm using CygWin on a Windows 2000 (SP1) box.
> >
> > I noticed a bug in the patch that shows up for CygWin users. The problem 
>is
> > that publickey authentication only works if sshd is running with the 
>same
> > user-id as the ssh client. When I run sshd as a service with a user-id 
>of
> > LocalSystem publickey authentication fails.
> >
> > This is because the check_nt_auth call in userauth-pubkey fails if the 
>ssh
> > user-id is different from the sshd user-id.
> >
> > It looks to me like userauth_pubkey needs to "suspend disbelief" (and 
>not
> > call check_nt_auth and auth_password) for partial authentication, in the
> > hope that a password may come later. Then somewhere check_nt_auth
> > auth_password need to be called to make sure that we don't forget to set 
>the
> > sshd user-id to the ssh user-id.
>
>Since the original partial authorization patch isn't applied yet,
>you're somwhat on your own. Why don't you simply override the
>check in `check_ntsec' for now?
>
>Corinna
>
>--
>Corinna Vinschen
>Cygwin Developer
>Red Hat, Inc.
> mailto:vinschen@redhat.com
>
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>Want to unsubscribe from this list?
>Check out: http://cygwin.com/ml/#unsubscribe-simple
>

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Re: Initial patch to implement partial auth with SSH2

[Corinna Vinschen]

On Fri, Apr 20, 2001 at 01:29:42AM -0700, Karl M wrote:
> Hi All...
> 
> I've been experimenting with the partial authorization patch for 
> OpenSSH-2.5.2. I'm using CygWin on a Windows 2000 (SP1) box.
> 
> I noticed a bug in the patch that shows up for CygWin users. The problem is 
> that publickey authentication only works if sshd is running with the same 
> user-id as the ssh client. When I run sshd as a service with a user-id of 
> LocalSystem publickey authentication fails.
> 
> This is because the check_nt_auth call in userauth-pubkey fails if the ssh 
> user-id is different from the sshd user-id.
> 
> It looks to me like userauth_pubkey needs to "suspend disbelief" (and not 
> call check_nt_auth and auth_password) for partial authentication, in the 
> hope that a password may come later. Then somewhere check_nt_auth 
> auth_password need to be called to make sure that we don't forget to set the 
> sshd user-id to the ssh user-id.

Since the original partial authorization patch isn't applied yet,
you're somwhat on your own. Why don't you simply override the
check in `check_ntsec' for now?

Corinna

-- 
Corinna Vinschen
Cygwin Developer
Red Hat, Inc.
mailto:vinschen@redhat.com

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Re: Initial patch to implement partial auth with SSH2

[Karl M]

Hi All...

I've been experimenting with the partial authorization patch for 
OpenSSH-2.5.2. I'm using CygWin on a Windows 2000 (SP1) box.

I noticed a bug in the patch that shows up for CygWin users. The problem is 
that publickey authentication only works if sshd is running with the same 
user-id as the ssh client. When I run sshd as a service with a user-id of 
LocalSystem publickey authentication fails.

This is because the check_nt_auth call in userauth-pubkey fails if the ssh 
user-id is different from the sshd user-id.

It looks to me like userauth_pubkey needs to "suspend disbelief" (and not 
call check_nt_auth and auth_password) for partial authentication, in the 
hope that a password may come later. Then somewhere check_nt_auth 
auth_password need to be called to make sure that we don't forget to set the 
sshd user-id to the ssh user-id.

Thanks,

...Karl
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