How to enable SSH access and configure network in rescue mode

In this quick tutorial we will show you how to enable SSH Access and configure network in rescue mode. Before you start boot into rescue mode using the DVD.

01/ Enable and Configure network in rescue mode

01- Show available network devices:

sh-4.2# ip link

1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eno16777984:  mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT qlen 1000
    link/ether 00:50:56:a3:5d:a3 brd ff:ff:ff:ff:ff:ff

02- Set the required network device UP:

sh-4.2# ip link set dev eno16777984 up

– Now use the below command to check the state of the device:

sh-4.2# ip link
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eno16777984:  mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether 00:50:56:a3:5d:a3 brd ff:ff:ff:ff:ff:ff

03- Now let’s assign an IP Address/netmask to the specific interface device:

sh-4.2# ip addr add 10.11.44.20/24 dev eno16777984

– After that, use the follow command to verify the assigned IP:

sh-4.2# ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eno16777984:  mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:50:56:a3:5d:a3 brd ff:ff:ff:ff:ff:ff
    inet 10.11.44.20/24 scope global eno16777984
       valid_lft forever preferred_lft forever
    inet6 fe80::250:56ff:fea3:5da3/64 scope link
       valid_lft forever preferred_lft forever

04- If needed, add the a static route to the network as below:

sh-4.2# ip route add default via 10.72.44.1

– Finally, verify the static route by running the below command:

sh-4.2# ip route
default via 10.11.44.1 dev eno16777984
10.11.44.0/24 dev eno16777984  proto kernel  scope link  src 10.11.44.20

02/ Enable SSH access in rescue mode

Everything is ready from a network point of view. Now we have to start SSH daemon so we can connect to the server.

01- First, we need to locate the ssh_config file:

sh-4.2# find / -name "*sshd_config*"
/etc/ssh/sshd_config.anaconda

02- Now, we need to create the sshd_config without it the SSH daemon won’t be able to start

sh-4.2# cp /etc/ssh/sshd_config.anaconda /etc/ssh/sshd_config

03- Finally, Start SSH daemon:

sh-4.2# systemctl start sshd

Conclusion

You have successfully learned how to enable and configure Network and SSH in rescue mode on your CentOS server. You might want to check the following guides:

• How to Reduce / Shrink the Size of a LVM Partition Formatted with XFS Filesystem?
• How To Reduce An LVM Swap Partition On CentOS 7 /RHEL 7

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