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Bug 799928 - [RFE] Hash the hostname/port information in the known_hosts file.
Summary: [RFE] Hash the hostname/port information in the known_hosts file.
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: sssd
Version: 6.3
Hardware: Unspecified
OS: Unspecified
high
unspecified
Target Milestone: rc
: ---
Assignee: Jakub Hrozek
QA Contact: Kaushik Banerjee
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2012-03-05 12:48 UTC by Stephen Gallagher
Modified: 2020-05-02 16:45 UTC (History)
4 users (show)

Fixed In Version: sssd-1.9.1-1.el6
Doc Type: Enhancement
Doc Text:
Do not document
Clone Of:
Environment:
Last Closed: 2013-02-21 09:20:13 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github SSSD sssd issues 2245 0 None closed Hash the hostname/port information in the known_hosts file. 2020-12-07 14:19:30 UTC
Red Hat Product Errata RHSA-2013:0508 0 normal SHIPPED_LIVE Low: sssd security, bug fix and enhancement update 2013-02-20 21:30:10 UTC

Description Stephen Gallagher 2012-03-05 12:48:45 UTC 
This bug is created as a clone of upstream ticket:
https://fedorahosted.org/sssd/ticket/1203

Last week I discussed the SSH known_hosts work with Honza. I thought about the stuff on the weekend. The plan is to have a global known_hosts file which gets written by sssd. This means that all users on this system have access which means reveal information to a lot of people who might not have this detailed information. So the hostnames should be stored hashed in the known_hosts file.

This way they do not reveal identifying information should the file's contents be disclosed. OpenSSH supports hashing since quite some time now.

Normally it looks like this:
{{{
|1|dTVaYG/giqH3nvoLfGECyOsiMDs=|RzAc9qu1lG+3ZtajFbaVuL02SZA= ssh-rsa ...
|1|base64(salt)|base64(hash)|
}}}
Here is some pseudo code for comparing it:

{{{
match_hashed_host(hostname, sourcehash) {

salt = base64_decode(sourcehash + 3)
hash = base64_decode(sourehash + strlen(salthash))

mac = sha1_hmac(hostname, salt)

if (mac == hash)
  woohoo
else
  cry
}
}}}
Comment 1 RHEL Program Management 2012-07-10 07:06:42 UTC 
This request was not resolved in time for the current release.
Red Hat invites you to ask your support representative to
propose this request, if still desired, for consideration in
the next release of Red Hat Enterprise Linux.
Comment 2 RHEL Program Management 2012-07-11 02:04:46 UTC 
This request was erroneously removed from consideration in Red Hat Enterprise Linux 6.4, which is currently under development.  This request will be evaluated for inclusion in Red Hat Enterprise Linux 6.4.
Comment 5 Scott Poore 2012-11-28 16:12:56 UTC 
Verified.

Version ::

sssd-1.9.2-21.el6.x86_64

Manual Test Results ::

[root@rhel6-1 log]# ssh rhel6-1.testrelm.com
root.com's password: 
Last login: Wed Nov 28 08:45:45 2012 from 192.168.122.1

[root@rhel6-1 ~]# exit
logout
Connection to rhel6-1.testrelm.com closed.

[root@rhel6-1 log]# ssh-keygen -H -F rhel6-1.testrelm.com -f /var/lib/sss/pubconf/known_hosts 
# Host rhel6-1.testrelm.com found: line 3 type RSA
|1|jzhcKuywO/syrzxU7BjbXAIa/kM=|RznFNMi4cWBK8/LXEdx2CqlCbSw= ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAxes4L818CAuJFLTL0MOwKaL6IbG92Mx3orn0ceOvz8OlWZ3VJADiBIXC9GdDTFEzJIqP5EW/WWb7hgbjBJ0h9zmD7onxgXZj+J9m28REl1ut03KldBYcBZPGyhYs+sKRCLSp1R5BT6laoq5rYxnQuDwCa8oljhnaCpBnWu9t7le3cfXmJfWfbnCFNB5FCPc/UDL/QwuLBiq0QNoRrjOgJqygtZ7EMP3csrYB/UxkNCvycGbZ6xg49HAcci064Ek6wz5GYD7/yFQB5bqvK1cAUkLjlL5m8Osw+McU+Z/aFz/5QfDHaEJ/krlCM8HPjEYv35CG0cYt1fHQKgYARxGMqw==
# Host rhel6-1.testrelm.com found: line 4 type DSA
|1|+/qqOvsp0eYFPHyUddi+YYn5XLs=|6nvBL7cSakbCOuXZXq5smAZ70qg= ssh-dss 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

[root@rhel6-1 log]# knownhost="$(ssh-keygen -H -F rhel6-1.testrelm.com -f /var/lib/sss/pubconf/known_hosts |grep ssh-rsa)"

[root@rhel6-1 log]# hostname=$(hostname)

[root@rhel6-1 log]# key=$(echo ${knownhost:3:28} | base64 -d | xxd -ps)

[root@rhel6-1 log]# mac1=$(echo ${knownhost:32:28} | base64 -d | xxd -ps)

[root@rhel6-1 log]# mac2=$(echo -n $hostname | openssl dgst -sha1 -mac HMAC -macopt hexkey:$key | awk '{ print $2 }')

[root@rhel6-1 log]# [ $mac1 = $mac2 ] && echo 'Keys match'
Keys match
Comment 6 errata-xmlrpc 2013-02-21 09:20:13 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2013-0508.html
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