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Just wanted a quick summary of the differences between them and why there are two? Cheers

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5  
Gotta love those sequential-numbered files where the numbers bear no relation to their function, version or description. –  Mark Henderson May 16 '11 at 0:04
    
@Mark Henderson: yes, what are other examples? –  smci Nov 26 '12 at 22:19

3 Answers 3

up vote 63 down vote accepted

In OpenSSH prior to version 3, the sshd man page used to say:

The $HOME/.ssh/authorized_keys file lists the RSA keys that are permitted for RSA authentication in SSH protocols 1.3 and 1.5 Similarly, the $HOME/.ssh/authorized_keys2 file lists the DSA and RSA keys that are permitted for public key authentication (PubkeyAuthentication) in SSH protocol 2.0.

The release announcement for version 3 states that authorized_keys2 is deprecated and all keys should be put in the authorized_keys file.

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The use of authorized_keys2 for protocol 2 has been deprecated since 2001.

[via]

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3  
If only someone would tell redhat that... authorized_keys fails, authorized_keys2 works fine. –  El Yobo Sep 20 '11 at 2:33
    
redhat stuff was last built in 2001 ;-) –  ring0 Aug 24 '12 at 2:13
    
So .. what IS the answer here - I am on CentOS 6.2? –  javadba Jul 7 at 15:21
    
@javadba: CentOS is in the same boat as Red Hat. –  Dennis Williamson Jul 7 at 15:36
    
@DennisWilliamson Right.. so is RH (/CentOS) requiring authorized_keys2 or not? My test just now indicates authorized_keys is sufficient.. but would be nice for more insight –  javadba Jul 7 at 16:02

version differentiation.

don't bother anymore, as now '2' can be ignored.

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protected by Khaled Jun 11 '12 at 8:24

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