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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 } }}}
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.
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.
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
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