Debian 與 DRBL 安裝筆記

Enable SSH root login on Debian Linux Server

After fresh system installation the root login on the Debian Linux is disabled by default. When you attempt to login as root user to your Debian Jessie Linux server the access will be denied eg.:

$ ssh root@10.1.1.12
root@10.1.1.12's password: 
Permission denied, please try again.
root@10.1.1.12's password: 
Permission denied, please try again.
root@10.1.1.12's password: 
Permission denied (publickey,password).

To enable SSH login for a root user on Debian Linux system you need to first configure SSH server. Open /etc/ssh/sshd_config and change the following line:

FROM:
PermitRootLogin without-password
TO:
PermitRootLogin yes

Once you made the above change restart your SSH server:

# /etc/init.d/ssh restart
[ ok ] Restarting ssh (via systemctl): ssh.service.

From now on you will be able to ssh login as a root:

$ ssh root@10.1.1.12
root@10.1.1.12's password: 

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.

5.5.3. The loopback network interface

The following configuration entry in the "/etc/network/interfaces" file brings up the loopback network interface lo upon booting the system (via autostanza).

auto lo
iface lo inet loopback

This one always exists in the "/etc/network/interfaces" file.

5.5.4. The network interface served by the DHCP

After preparing the system by Section 5.4.1, “The DHCP connection with the Ethernet”, the network interface served by the DHCP is configured by creating the configuration entry in the "/etc/network/interfaces" file as the following.

allow-hotplug eth0
iface eth0 inet dhcp

When the Linux kernel detects the physical interface eth0, the allow-hotplug stanza causes ifup to bring up the interface and the iface stanza causesifup to use DHCP to configure the interface.

5.5.5. The network interface with the static IP

The network interface served by the static IP is configured by creating the configuration entry in the "/etc/network/interfaces" file as the following.

allow-hotplug eth0
iface eth0 inet static
 address 192.168.11.100
 netmask 255.255.255.0
 gateway 192.168.11.1
 dns-domain example.com
 dns-nameservers 192.168.11.1

When the Linux kernel detects the physical interface eth0, the allow-hotplug stanza causes ifup to bring up the interface and the iface stanza causesifup to use the static IP to configure the interface.
Here, I assumed the following.

• IP address range of the LAN network: 192.168.11.0 - 192.168.11.255
• IP address of the gateway: 192.168.11.1
• IP address of the PC: 192.168.11.100
• The resolvconf package: installed
• The domain name: "example.com"
• IP address of the DNS server: 192.168.11.1

When the resolvconf package is not installed, DNS related configuration needs to be done manually by editing the "/etc/resolv.conf" as the following.

nameserver 192.168.11.1
domain example.com

	Caution
	The IP addresses used in the above example are not meant to be copied literally. You have to adjust IP numbers to your actual network configuration.

參考網址：
https://www.debian.org/doc/manuals/debian-reference/ch05.en.html#_the_network_interface_with_the_static_ip


https://linuxconfig.org/enable-ssh-root-login-on-debian-linux-server