Macos – SSH remote login without password is very slow

debianmacosopenssh

SSH Client – Mac OS X Lion
SSH Server – Debian

/etc/hosts on Mac -> [IP of Debian] mydebian
Public key of Mac has already been put to authorized_key in root@mydebian:/root/.ssh
'UseDNS no' has been put to root@mydebian:/etc/ssh/sshd_config and then SSH server restarted

ssh root@mydebian -> wait for a long time to login
ssh -v root@mydebian -> no delay at all

Any ideas?

Best Answer

Set the following value in /etc/ssh_config:

AddressFamily inet

(You can set it in ~/.ssh/config as well.)

The reason is that ssh is trying to do IPv6 negotiation, which apparently fails after a timeout, which happened to me after migration to a new Lion (10.7.4) MacBook Pro.

Related Solutions

Macos – How to ssh-login into the Mac as root

Migrated to an answer:

Per Apple:

  By default, the root user is not enabled [in Mountain Lion].

Which means, unless you have enabled the account and set the password - you probably do not have the root user even enabled. Per the link above:

Enable the root user
   1. Choose Apple menu > System Preferences, and then click Users & Groups.
   2. Click the lock icon to unlock it, and then type an administrator name and password.
   3. In the Network Account Server section, click Join or Edit.
   4. Click Open Directory Utility.
   5. Click the lock icon to unlock it, and then enter your administrator name and password.
   6. Choose Edit > Enable Root User, and then enter a root user password in the Password and Verify fields.
 Be sure to specify a secure password.

Then you can test that it works via SSH and WinSCP.

Shorter Unix way

Open Terminal and run

sudo passwd

enter your sudoing password if needed, and then provide the password for the root account when asked.

And don't forget to add "Administrators" to the list of users allowed for remote login.

Ubuntu – Secure remote editing of root-accessible files over SSH

If the remote editing is really wanted, one simple solution could be to keep a copy of /etc (or parts of it) on another local user and setup the system to copy changes from there to the real /etc. Even better would be to use a git -- or svn, or any other version control system of your choice -- and you would have additional log of changes, too.

It's also possible to setup chroot on SFTP and disable normal login for a specific account -- or limiting the login to that user only from specified IP addresses -- with the same feature of OpenSSH (Match Group etc). About that, check http://www.thegeekstuff.com/2012/03/chroot-sftp-setup/

However please remember that most configuration files on /etc make it possible to get root access just by editing them. I've seen systems configured with svn/git to check the validation of configuration files before accepting changes of the files -- that could be used for accepting only secure configuration formats.

Anyway, there's a lot of different solutions for the problem. This was only one approach.

Best Answer

Related Solutions

Macos – How to ssh-login into the Mac as root

Ubuntu – Secure remote editing of root-accessible files over SSH

Related Question