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Full Discussion: Change from weak ssh host key to strong one
Operating Systems Solaris Change from weak ssh host key to strong one Post 303036682 by rbatte1 on Monday 8th of July 2019 05:35:10 AM
Old 07-08-2019
Just came across this. One thing to be aware of is that all clients will object when you next try to connect them. They will alert on there being a possible man-in-the-middle attack or a DNS attack that is trying to send you to a different host (as determined by the keys) so you would need to get each client to forget the server keys for the machine(s) you are replacing the keys on and re-validate them all, or manually replace the old key with the new on all the clients.

You need to consider all the names that the clients could refer to the server as, be that IP, local hosts, DNS short name, fully qualified DNS name, DNS alias etc. and look for those in ~/.ssh/known_hosts

You will need to do this for every account on every client, so it is not a thing to be done lightly, especially if there are multiple automated jobs that connect with SSH, SCP, SFTP etc. that you need to ensure are not disrupted.


Sorry if I've made you panic, but better that than a massive failure.



I hope that this helps,
Robin
 

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LEARN ABOUT CENTOS

ipa-replica-install

ipa-replica-install(1)						 IPA Manual Pages					    ipa-replica-install(1)

NAME

       ipa-replica-install - Create an IPA replica

SYNOPSIS

       ipa-replica-install [OPTION]... replica_file

DESCRIPTION

       Configures a new IPA server that is a replica of the server that generated it. Once it has been created it is an exact copy of the original
       IPA server and is an equal master. Changes made to any master are automatically replicated to other masters.

       The replica_file is created using the ipa-replica-prepare utility.

       If the installation fails you may need to run ipa-server-install --uninstall before running ipa-replica-install again.

       The installation will fail if the host you are installing the replica on exists as a host in  IPA  or  an  existing  replication  agreement
       exists (for example, from a previously failed installation).

       A replica should only be installed on the same or higher version of IPA on the remote system.

OPTIONS

   BASIC OPTIONS
       --setup-ca
	      Install and configure a CA on this replica. If a CA is not configured then certificate operations will be forwarded to a master with
	      a CA installed.

       --ip-address=IP_ADDRESS
	      The IP address of this server. If this address does not match the address the host resolves to and --setup-dns is not  selected  the
	      installation will fail. If the server hostname is not resolvable, a record for the hostname and IP_ADDRESS is added to /etc/hosts.

       -p DM_PASSWORD, --password=DM_PASSWORD
	      Directory Manager (existing master) password

       -w ADMIN_PASSWORD, --admin-password=ADMIN_PASSWORD
	      Admin user Kerberos password used for connection check

       --mkhomedir
	      Create home directories for users on their first login

       -N, --no-ntp
	      Do not configure NTP

       --no-ui-redirect
	      Do not automatically redirect to the Web UI.

       --ssh-trust-dns
	      Configure OpenSSH client to trust DNS SSHFP records.

       --no-ssh
	      Do not configure OpenSSH client.

       --no-sshd
	      Do not configure OpenSSH server.

       --skip-conncheck
	      Skip connection check to remote master

       -d, --debug
	      Enable debug logging when more verbose output is needed

       -U, --unattended
	      An unattended installation that will never prompt for user input

   CERTIFICATE SYSTEM OPTIONS
       --skip-schema-check
	      Skip check for updated CA DS schema on the remote master

   DNS OPTIONS
       --setup-dns
	      Generate	a  DNS	zone  if  it does not exist already and configure the DNS server.  This option requires that you either specify at
	      least one DNS forwarder through the --forwarder option or use the --no-forwarders option.

       --forwarder=IP_ADDRESS
	      Add a DNS forwarder to the DNS configuration. You can use this option multiple times to specify more forwarders, but  at	least  one
	      must be provided, unless the --no-forwarders option is specified.

       --no-forwarders
	      Do not add any DNS forwarders. Root DNS servers will be used instead.

       --reverse-zone=REVERSE_ZONE
	      The reverse DNS zone to use

       --no-reverse
	      Do not create new reverse DNS zone. If a reverse DNS zone already exists for the subnet, it will be used.

       --no-host-dns
	      Do not use DNS for hostname lookup during installation

       --no-dns-sshfp
	      Do not automatically create DNS SSHFP records.

EXIT STATUS

       0 if the command was successful

       1 if an error occurred

       3 if the host exists in the IPA server or a replication agreement to the remote master already exists

IPA
								    May 16 2012 					    ipa-replica-install(1)
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