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Host-key rotation in OpenSSH 6.8
- peterwwillis 12y agoI'm not sure I understand why this feature was added. Providing new keys - and revoking them - already works using SSH's CA support: https://www.digitalocean.com/community/tutorials/how-to-create-an-ssh-ca-to-validate-hosts-and-clients-with-ubuntu https://www.digitalocean.com/community/tutorials/how-to-crea... A client can verify new Host keys, and a server can verify new user keys, all by checking if it's signed or revoked by the CA. This prevents a client from receiving a host key generated by an attacker on a compromised host, and it allows a server to authenticate clients even if they've never received the client user's key. If this functionality is used properly, it should be more secure than the new feature mentioned above. The only advantage the new feature has is it'll work with clients that support the new feature without having to modify their configuration (but it still doesn't provide all the features or security the CA provides).
- petrosagg 12y agoI think the main problem is that there are a lot of SSH servers already deployed without using the CA approach and migrating HostKeys is a pain without causing horrible warnings to the clients. Take GitHub for example. If this feature was mainstream they would be able to phase out their DSA key without people noticing.