What are common mistakes admin makes his Linux remote server inaccessible via SSH?

postcd

Hello,

which common mistakes leads into state where admin of the remote linux (Ubuntu, CentOS) server cant access it via SSH? I mean even reboot do not help to gain access.

So we made some checklist and maybe write a script that would fix the things if they are broken.

Thank You

hostnoob

wat

how would a script/checklist help if you can't gain SSH access?

exception0x876

ok here is the script, assuming you stored backups of the necessary files in the /backup directory. since you can't run the script (remember, you have no SSH access!), you need to create some way to execute it remotely.

WARNING, it is made mostly for fun, not for the real world usage. Use it at your own risk!

#!/bin/bash

yum install openssh #replace with package manager command for your OS, this is in case you deleted SSH server
cp /backup/sshd_config /etc/ssh/sshd_config #in case you messed up the config file
setenforce 0 #in case you messed the SELinux policy
cp /backup/authorized_keys /root/.ssh/authorized_keys #you could also delete your public key
iptables -F
service sshd restart #replace with the command for your OS

I guess that covers the basics.

budi1413

Block port 22 lel.

khuongcomputer

Block port 22, open port xyz, changed sshd config but forgot to restart it lol.

robohost

Set no root login and not set ssh key, block port 22

Mad

Kick off himself due to wrong firewall rules.

lukesUbuntu

maybe they did a rm -rf /

its possible someone on serverfault posted an admin mistake http://serverfault.com/questions/769357/recovering-from-a-rm-rf

grimsdottir

Turn off password authentication but forget to add RSA key...then restart sshd

AshleyUk

@grimsdottir said:
Turn off password authentication but forget to add RSA key...then restart sshd

Never close your current session down till you know you have a working setup

grimsdottir

@AshleyUk said:
Never close your current session down till you know you have a working setup

You only do it once...

elwebmaster

Change the permissions on your home folder to 777.