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Category:   Application (Security)  >   OpenSSH Vendors:
(Red Hat Issues Additional Fix) OpenSSH May Fail to Properly Restrict IP Addresses in Certain Configurations
SecurityTracker Alert ID:  1002609
SecurityTracker URL:
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Oct 22 2001
Impact:   Host/resource access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): Versions of OpenSSH between 2.5 and 2.9.9
Description:   OpenSSH reported a weakness in OpenSSH's IP-based access control functions when configured for SSH v2 public key authentication. Remote users connecting from IP addresses that are to be restricted may be able to connect.

The vulnerability is due to a weakness in the source IP address access control features in the key file option handling. When source IP based access control is used for SSH protocol v2 public key authentication, the access controls may fail if the 'from=' key file option is enabled in combination with both RSA and DSA keys in the '~/.ssh/authorized_keys2' file.

Whether the vulnerability can be triggered or not reportedly depends on the order of the user keys in the file. If a source IP restricted key (e.g., DSA key) is immediately followed by a different type of key (e.g., RSA key), then the key options for the second key will be applied to both keys. These options include the 'from=' restriction.

OpenSSH reports that the fixed version (2.9.9) contains some changes that may affect users upgrading from previous versions. See the Source Message for details.

Impact:   Remote users with valid authentication credentials can circumvent the system policy and login from disallowed source IP addresses.
Solution:   The vendor has released a fix. See the Source Message for the file locations and upgrade instructions.
Vendor URL: (Links to External Site)
Cause:   Access control error
Underlying OS:  Linux (Red Hat Linux)

Message History:   This archive entry is a follow-up to the message listed below.
Sep 26 2001 OpenSSH May Fail to Properly Restrict IP Addresses in Certain Configurations

 Source Message Contents

Subject:  [RHSA-2001:114-05] Updated openssh packages available

                   Red Hat, Inc. Red Hat Security Advisory

Synopsis:          Updated openssh packages available
Advisory ID:       RHSA-2001:114-05
Issue date:        2001-09-27
Updated on:        2001-10-19
Product:           Red Hat Linux
Keywords:          openssh source IP
Cross references:  

1. Topic:

Updated openssh packages are now available for Red Hat Linux 7 and 7.1.
These packages fix a vulnerability which may allow unauthorized users to
log in from hosts that have been denied access.

2001-10-22: Pacakges are now available for Red Hat Linux 7.2.

2. Relevant releases/architectures:

Red Hat Linux 7.0 - alpha, i386

Red Hat Linux 7.1 - alpha, i386, ia64

Red Hat Linux 7.2 - i386

3. Problem description:

If a user lists multiple keys in her .ssh/authorized_keys2 file, sshd may
in some circumstances not honor the "from" option which can be associated
with a key, thereby allowing key-based logins from hosts which should not
be allowed access.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade.  Only those
RPMs which are currently installed will be updated.  Those RPMs which are
not installed but included in the list will not be updated.  Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network.  Many
people find this an easier way to apply updates.  To use Red Hat Network,
launch the Red Hat Update Agent with the following command:


This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

5. Bug IDs fixed ( for more info):

6. RPMs required:

Red Hat Linux 7.0:




Red Hat Linux 7.1:





Red Hat Linux 7.2:



7. Verification:

MD5 sum                           Package Name
2cb978dd97527b75dd765cc7866747be 7.0/en/os/SRPMS/openssh-2.9p2-8.7.src.rpm
3f25b21ea52cf287b3f92dde9ebeb6e5 7.0/en/os/alpha/openssh-2.9p2-8.7.alpha.rpm
0aa7e84cf7051625c266fd06097f5421 7.0/en/os/alpha/openssh-askpass-2.9p2-8.7.alpha.rpm
b0bc920fb83c38f91696283ae9a35c70 7.0/en/os/alpha/openssh-askpass-gnome-2.9p2-8.7.alpha.rpm
3ba198d73c0c2b98b1d28b1209529704 7.0/en/os/alpha/openssh-clients-2.9p2-8.7.alpha.rpm
b6190a028673032994ccc21cf2a1d620 7.0/en/os/alpha/openssh-server-2.9p2-8.7.alpha.rpm
968125b43cb68330aa58a85e082573c6 7.0/en/os/i386/openssh-2.9p2-8.7.i386.rpm
913350e14f7e40c1cbaaf01a68ff2af6 7.0/en/os/i386/openssh-askpass-2.9p2-8.7.i386.rpm
62aac745851160f5805eaee52cdb6eb9 7.0/en/os/i386/openssh-askpass-gnome-2.9p2-8.7.i386.rpm
d2831ff8f3032462b511ec9bd8e486f2 7.0/en/os/i386/openssh-clients-2.9p2-8.7.i386.rpm
3a995bf67827eaa272976df85939d778 7.0/en/os/i386/openssh-server-2.9p2-8.7.i386.rpm
2cb978dd97527b75dd765cc7866747be 7.1/en/os/SRPMS/openssh-2.9p2-8.7.src.rpm
917606bec87a2598db083075248d63f3 7.1/en/os/alpha/openssh-2.9p2-8.7.alpha.rpm
59e697845982082983be668c1491f478 7.1/en/os/alpha/openssh-askpass-2.9p2-8.7.alpha.rpm
b1a4c72deb5086d80b0065cd1ddf6ce4 7.1/en/os/alpha/openssh-askpass-gnome-2.9p2-8.7.alpha.rpm
16523f9c4e76c077dc10505fa1c46f2f 7.1/en/os/alpha/openssh-clients-2.9p2-8.7.alpha.rpm
4844484c7174ee970617579a4355639d 7.1/en/os/alpha/openssh-server-2.9p2-8.7.alpha.rpm
968125b43cb68330aa58a85e082573c6 7.1/en/os/i386/openssh-2.9p2-8.7.i386.rpm
913350e14f7e40c1cbaaf01a68ff2af6 7.1/en/os/i386/openssh-askpass-2.9p2-8.7.i386.rpm
62aac745851160f5805eaee52cdb6eb9 7.1/en/os/i386/openssh-askpass-gnome-2.9p2-8.7.i386.rpm
d2831ff8f3032462b511ec9bd8e486f2 7.1/en/os/i386/openssh-clients-2.9p2-8.7.i386.rpm
3a995bf67827eaa272976df85939d778 7.1/en/os/i386/openssh-server-2.9p2-8.7.i386.rpm
d2cfbc8f711499f14e850e3a39216b72 7.1/en/os/ia64/openssh-2.9p2-8.7.ia64.rpm
676181a27221581a0144d5987d42e5d8 7.1/en/os/ia64/openssh-askpass-2.9p2-8.7.ia64.rpm
48455412e34bd704d6c7516f5ed8208c 7.1/en/os/ia64/openssh-askpass-gnome-2.9p2-8.7.ia64.rpm
225d83ddfebb3eba7fe290c33c5c41cf 7.1/en/os/ia64/openssh-clients-2.9p2-8.7.ia64.rpm
b6cfceece2ac8f5060ab63d6f7254770 7.1/en/os/ia64/openssh-server-2.9p2-8.7.ia64.rpm
b8962a6f832e333d8fcf8782228f78e3 7.2/en/os/SRPMS/openssh-2.9p2-9.src.rpm
c553416074a5fc54d309c6e7653f684a 7.2/en/os/i386/openssh-2.9p2-9.i386.rpm
557a7615d1abf68e4b2bb998c0091638 7.2/en/os/i386/openssh-askpass-2.9p2-9.i386.rpm
4b1df978407683e2c160f496f24e26e5 7.2/en/os/i386/openssh-askpass-gnome-2.9p2-9.i386.rpm
f35d0f0b45fd5fd3ceb06589ca18aab3 7.2/en/os/i386/openssh-clients-2.9p2-9.i386.rpm
d9fcc0d6d03c59b04681d6e755e3cb92 7.2/en/os/i386/openssh-server-2.9p2-9.i386.rpm

These packages are GPG signed by Red Hat, Inc. for security.  Our key
is available at:

You can verify each package with the following command:
    rpm --checksig  <filename>

If you only wish to verify that each package has not been corrupted or
tampered with, examine only the md5sum with the following command:
    rpm --checksig --nogpg <filename>

8. References:

Copyright(c) 2000, 2001 Red Hat, Inc.

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