Summary We recently encountered with ‘sshd error: could not load host key’. The fixing is quite easy in Ubuntu Linux system yet you should be careful while solving the issue. This time we found this problem in Ubuntu 18.04 LTS Server Edition whereas the method is applicable to other Ubuntu and Debian based Linux Operating […]
ssh
Centralize authorized_keys file on Linux / Unix system
Authorized_keys are important files which has the information of public keys for public key authentication. By default location is ~/.ssh/authorized_keys. Here, ~ is users default home directory in system. While working on SSH, we got requirement to centralize the authorized_keys of all users existing in system. In most of the system for SSH we use […]
Protect ssh with Google Authenticator on Ubuntu 14.04 LTS
The tutorial is about how we can protect ssh with Google Authenticator on Ubuntu 14.04 LTS server . Google authenticator is a security application which implements time based one time password (TOTP) security tokens. It is often also called as “Two steps verification” . The server in which Google Authenticator has been setup , to […]
How to create OpenSSH rpm package and its upgrade
In this tutorial we will create rpm package of OpenSSH version 6.7 stable version and will do OpenSSH upgrade. You may be wondering why it is required to create rpm package of OpenSSH version. The answer is because of CVE-2014-2532 . We recently notified with the CVE-2014-2532 , which is a openssh AcceptEnv environment restriction […]
error: Could not load host key
Recently while upgrading the OpenSSH server, we faced some issue. This time, the issue was related to ssh key and we got number of lines in message log file with information – “error: Could not load host key” . Here are some brief detail taken from our system. Jan 17 11:14:10 localhost sshd[6294]: error: Could […]
error: Could not get shadow information for root
Recently created rpm package from OpenSSH 6.7 tar ball package. After successfully creating rpm and upgrading the OpenSSH server, met with issue – error: Could not get shadow information for root .Given below is some section of the error found in messages log (/var/log/messages)Jan 17 11:21:17 localhost systemd: Started SYSV: OpenSSH server daemon.Jan 17 11:21:26 […]
Install Openssh server on Ubuntu Desktop / Server
FAQ : How to connect to Ubuntu Desktop / Server by using ssh. I just installed Ubuntu 14.04 LTS Desktop edition and have not found ssh service running in system. Answer : OpenSSH is a FREE version of the SSH connectivity tools. It provides the encrypted communication between computers by using ssh protocol. History of […]
CentOS 7 / RHEL 7 : change OpenSSH port number ( SELINUX enabled )
The tutorial will explain about how to change default ssh port number in OpenSSH Server on CentOS 7 and RHEL 7 . We will change the SSH default port no. 22 to our desired number and we will keep SELINUX enabled. We will also add new firewalld rule with respect to new ssh port number. […]
How to install ssh server on Ubuntu
SSH, the abbreviation is Secure Shell. It is a software program use the secure shell protocol to accept connection from remote computers.SSH is TCP based protocol. By default the ssh protocol listen at port no. 22 . You can also customize the port number but always remember while changing the ssh port no. it should […]
SCP file and directory in linux and Unix like operating system
SCP stands for secure copy.It is based upon SSH (Secure Shell) protocol.SCP is used for securely transferring the files between local and remote system. Note: If SSH service is not running or deny by firewall or IPTABLES of system then SCP will also not work. Syntax: scp SOURCE-FILE-LOCATION TARGET-LOCATION (1) SCP file from local to […]
run command in remote linux / unix system by using ssh
How to run command in remote linux / unix system by using ssh If you are working as a linux system admin, it is important to know how you can execute the command in remote linux or unix based operating system by using ssh.The method is very useful and you can also use it in […]
how to deny root ssh access in linux server
how to deny root ssh access in linux server For security point of view we generally restrict root direct ssh access in server.But keep in mind you also must have user who can access the server other than root. So before doing this practical ,check if you have access to server with other user or […]
Change the default port number of ssh server
Change the default port number of ssh server SSH Default Port no. = 22 To change the default port number of ssh server hardly takes a few steps but with the point of security it is important to change the default port no. 22 After this you can also use the anti port scan script […]
SSH WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED
When you try to ssh the another remote Linux/Unix machine , you might have encountered with the WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! . This message we have often seen when we work in Linux machines. In this post we have provided the Reason and Solution on this Warning. root@tuxworld:/tmp# ssh 10.10.0.16 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: […]
How To Get SSH Public Key Fingerprint Information
Long time ago one of my U.S system admin was very security conscious. He asked me to create id_rsa.pub key in server. I created the key with ssh-keygen -t rsa command. And send it him through encrypted email. Next day he wrote me ,what is the ssh key fingerprint ? First let’s have some introduction. […]