ssh-host-key-invalid.md

試著用 ssh_setup 設定多台 Server 間的 ssh key，有個錯誤是這樣的：

[server@www ~]# ssh-keygen -R aaa.bbb.ccc.ddd
line 63 invalid key: aaa.bbb.ccc.ddd...
/server/.ssh/known_hosts is not a valid known_host file.
Not replacing existing known_hosts file because of errors
You have new mail in /var/spool/mail/server

它認為第 63 行是不合法的：

aaa.bbb.ccc.ddd ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTIt....
aaa.bbb.ccc.ddd ssh-rsa AAAAB3Nza....

其中含 ecdsa-sha2-nistp256 是 script 寫進來的，它來自一台比較新的 ec2 server，而出問題的電腦裝的是 Fedora Core 8。分別查詢 man ssh_config 可以知兩者支援的 HostKeyAlgorithms 有何不同：

     HostKeyAlgorithms
             Specifies the protocol version 2 host key algorithms that the client wants to use in order of preference.  The default for this option is:

                [email protected],
                [email protected],
                [email protected],
                [email protected],[email protected],
                [email protected],[email protected],
                ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
                ssh-rsa,ssh-dss

     HostKeyAlgorithms
             Specifies the protocol version 2 host key algorithms that the client wants to use in order of preference.  The default for this option is: “ssh-rsa,ssh-dss”.

看來要符合 2 台都支援，只能選用 ssh-rsa 或 ssh-dss 的格式。

qrtt1/ssh-host-key-invalid.md