sshd configuration (DSA authentication)

Posted by: admin at 11 Monday 8th, 2008

FreeBSD sshd is by default to boot. 
 # which sshd
/usr/sbin/sshd
So, after the /etc/ssh/sshd_config to AllowUsers USERNAME only that, BURUTOFOSUATAKKU (brute force attacks) against the DSA should be authenticated.
If you look you see the access log, or the humble country crackers or分RIMASEN bots, you should find that traces of the attack.

Rewrite of the configuration file

/etc/ssh/sshd_config 
 Protocol 2
SSH2 protocol used 
 PermitRootLogin no
disable root login in 
 PubkeyAuthentication yes
Authentication Using DSA 
 PasswordAuthentication no
PermitEmptyPasswords no
No and no and no password authentication and password 
 ChallengeResponseAuthentication no
So no to no the password on it.

After rewriting sshd restart. 
 # /etc/rc.d/sshd restart
Or, in earlier versions may also be an error because, if it is in the following way. 
 # ps aux | grep sshd
# kill -HUP  PID

Private key id_dsa and public key id_dsa.pub to generate

Log in with ssh to enable users to access. root other)
Enter the following command. 
 $ ssh-keygen -d 
 Generating public/private dsa key pair.
Enter file in which to save the key (/home/ USERNAME /.ssh/id_dsa):    [Enter] 
Created directory '/home/ USERNAME /.ssh'.
Enter passphrase (empty for no passphrase):                      [PASSWORD] [Enter] 
Enter same passphrase again:                                     [Re PASSWORD] [Enter] 
Your identification has been saved in /home/ USERNAME /.ssh/id_dsa.
Your public key has been saved in /home/ USERNAME /.ssh/id_dsa.pub.
The key fingerprint is:
xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx  USERNAME @ HOST . DOMAIN . NAME

Public key id_dsa.pub to rename the 

 $ cd /home/ USERNAME /.ssh
$ mv id_dsa.pub authorized_keys
$ chmod 0600 authorized_keys

Private key id_dsa to move to a client machine

ssh client to connect to the /home/ USERNAME /.ssh/id_dsa move. If you are concerned about security, FTP, etc. There is no USB floppy disk is a good memory and do in the process of using the media attention.
id_dsa to save the file, it will depend on the client terminal, please refer to your manual.
Personally open source Tera Term is a good idea.

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