Creating a Local YUM Repository with ISO

In Order to install or Update software in RHEL we need to connect to RHN (RedHat Network). By creating Local Repository we can install software from our own device. It saves things like bandwidth and time. All we need is an iso image (CD/DVD image).

Download the iso file from redhat.com and place it in /iso directory

To Create a local repository; create a configuration file in /etc/yum.repos.d/ as *.repo

vim /etc/yum.repos.d/trs-local.repo
[trstech]
name=This is Local Repository
baseurl=file:///localrepo
gpgcheck=0
enabled=1

In this configuration file we have defined the repo url as a file and it is in /localrepo.
But in order to access that, we have to mount the iso file to that directory.
mkdir /localrepo
mount -o loop,ro /iso/rhel7.iso /localrepo
But this mount is not persistent, for persistent mount we have to edit the /etc/fstab file

vim /etc/fstab
/iso/rhel7.iso /localrepo iso9660 loop,ro 0 0
mount -a

then verify whether you have access to the local repository by giving a command
yum repolist
Now install package and play with the services

How to install and configure SSH server on RHEL 7

Install SSH server

To commence you must install the SSH server (and client). There are many servers that you can choose from, but today we’re going to install OpenSSH, probably the most popular one.

1	# yum install -y openssh-server openssh-clients

If everything goes well, you will have a SSH server installed and a key for the host configured. Next thing is to enable and start the service using systemd. And next is opening the appropriate firewall port. I assume you’re using firewalld instead of iptables.

1 2 3 4

# systemctl start sshd # systemctl enable sshd # firewall-cmd --permanent --add-service ssh # firewall-cmd --reload

This ensures the SSH server is loaded and started at boot time, and start it right now. Ok, end of the story. It can indeed work like this, but you should also take a few minutes to configure your new SSH server. First you should familiarize with the configuration folder: /etc/ssh . You will find a few files inside this folder, the configuration of the server resides however in the sshd_config file.

Configuring SSH server

There are many many configuration options, we’ll cover the most important ones.

1 2 3 4 5 6 7 8

Port 22                    # Tells sshd to listen on the port AddressFamily any          # Listen on IPv4 or IPv6 only or both ListenAddress 0.0.0.0      # Listen on the address specified, can use both IPv4 and IPv6 PermitRootLogin no         # Allow root to use ssh, it should always be set to no MaxAuthTries 6             # Defines the number of tries allowed during login MaxSessions 10             # Defines the maximum number of simultaneous connections PubkeyAuthentication yes   # If set to yes enables the use of public key authentication PasswordAuthentication yes # This will enforce key-based if set to no and ask passwords if set to yes

This is by no mean a complete list, but shows you the most used (and important) options. If you’re willing here’s the complete list. Be sure to reload sshd for the changes to take effect

1	# systemctl reload sshd

Also, changing the port or the address will require a restart of the SSH server.