problems with passwordless log in as root with SSH

Mountain · 05-05-2009, 01:16 PM

In /etc/ssh/sshd_config if I use this line, passwordless login works as intended:

Code:

# Authentication:
PermitRootLogin yes
AllowUsers root@*

But if I change it to this (which is what I want for better security), the login is not permitted. (It asks for a password, and no root password exists.)

Code:

# Authentication:
PermitRootLogin yes
AllowUsers root@192.168.100.101

The client has this IP address:

Code:

$ ifconfig
eth1      Link encap:Ethernet  HWaddr xxxxxxxxxxxxxx  
          inet addr:192.168.100.101

and eth1 is the active interface.

So why does the login not work when I specify the IP address that is allowed, but it does work when I open it up to any IP addresses?

How would you trouble shoot this? Which log should I look in to find the IP address that is attempting to log in?

Mountain · 05-05-2009, 01:28 PM

I discovered auth.log. It showed me the clues I needed.

The hosts file on the ssh server has an entry like this:

Code:

192.168.100.101 	myclient.asdf.xx.my_isp.org	myclient

I had tried both the IP address and the short host name. But I saw in auth.log that the access denial was listing my fully qualified host name.

So I changed /etc/ssh/sshd_config to this:

Code:

AllowUsers root@myclient.asdf.xx.my_isp.org

Now it works.