Recipe 17.13. Setting File Permissions on ssh Files

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17.13.1 Problem

You want to be sure that your SSH files and keys have the correct, most secure permissions.

17.13.2 Solution

For user accounts in ~/.ssh, use the following permissions:

~/.ssh	mode 700
~/.ssh/id_dsa and other private keys	mode 400
~/.ssh/id_dsa.pub and other public keys	mode 644
~/.ssh/ssh_config	mode 644
~/.ssh/known_hosts	mode 644
~/.ssh/authorized_keys	mode 644

Files in /etc/ssh should have these permissions:

/etc/ssh	mode 755
/etc/ssh/sshd_config	mode 644
/etc/ssh/ssh_config	mode 644
/etc/ssh/ssh_host_dsa_key and other private keys	mode 400
/etc/ssh/ssh_host_dsa_key.pub and other public keys	mode 644
/etc/ssh/moduli	mode 644

17.13.3 Discussion

File permissions and ownership are fundamental security tools in Linux, so it's important to be careful and make sure to get them right. Again, beware of text editors that create automatic backup copies, and be careful when you delete files. If they sit in the Trash, they can easily be retrieved.

17.13.4 See Also

ssh(1), sshd(8)
SSH, The Secure Shell: The Definitive Guide

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