How to activate your no-cost RHEL subscription

This article is taken from RedHat Developer How to activate your no-cost Red Hat Enterprise Linux subscription. 3 Simple Steps were described in the article.

  • Step 1: Make sure you have a Red Hat account
  • Step 2: Download no-cost RHEL
  • Step 3: Register your RHEL subscription

As Developer, you have up to 16 subscription free-of-charge

Session Trunking for NFS available in RHEL-8

This Article is taken from Is NFS session trunking available in RHEL?

Session trunking, whereby one can have multiple TCP connections to the same NFS server with the same IP address is provided by nconnect. This feature is available in RHEL 8

RHSA-2020:4431 for the package(s) kernel-4.18.0-240.el8 or later.
RHBA-2020:4530 for the package(s) nfs-utils-2.3.3-35.el8 libnfsidmap-2.3.3-35.el8 or later.

You can configure on the client side up to 16 connection

[root@nfs-client ~]# mount -t nfs /nfs-share -o nosharecache,nconnect=16

You can see by using the command

[root@nfs-client ~]# cat /proc/self/mountstats
RPC iostats version: 1.1  p/v: 100003/4 (nfs)
    xprt:   tcp 991 0 2 0 39 13 13 0 13 0 2 0 0
    xprt:   tcp 798 0 2 0 39 6 6 0 6 0 2 0 0
    xprt:   tcp 768 0 2 0 39 6 6 0 6 0 2 0 0
    xprt:   tcp 1013 0 2 0 39 4 4 0 4 0 2 0 0
    xprt:   tcp 828 0 2 0 39 4 4 0 4 0 2 0 0
    xprt:   tcp 702 0 2 0 39 2 2 0 2 0 2 0 0
    xprt:   tcp 783 0 2 0 39 2 2 0 2 0 2 0 0
    xprt:   tcp 858 0 2 0 39 2 2 0 2 0 2 0 0

Someone recorded multiple performance increase when used on Pure Storage acting as a NFS Server. at Use nconnect to effortlessly increase NFS performance

Pix Taken from Use nconnect to effortlessly increase NFS performance


  1. Is NFS session trunking available in RHEL?
  2. Use nconnect to effortlessly increase NFS performance
  3. Explanation of NFS mount options: nconnect=, nosharetransport, sharetransport=

Creating a Self-Signed Certificate on RHEL

You can create your own self-signed certificate. Note that a self-signed certificate does not provide the security guarantees of a CA-signed certificate.

Generating a Key

Taken from RHEL Administration Guide 25.6. GENERATING A KEY and Creating a Self-Signed Certificate

Step 1: Clean up fake key and certificate

Go to /etc/httpd/conf/ directory. Remove the fake key and certificate that were generated during the installation

# cd /etc/httpd/conf/
# rm ssl.key/server.keyrm ssl.crt/server.crt

Step 2: Create your own Random Key

Go to usr/share/ssl/certs/ and generate key

# cd /usr/share/ssl/certs/
# make genkey

Your system displays a message similar to the following:

mask 77 ; \
/usr/bin/openssl genrsa -des3 1024 > /etc/httpd/conf/ssl.key/server.key
Generating RSA private key, 1024 bit long modulus
e is 65537 (0x10001)
Enter pass phrase:

You now must enter in a passphrase. For security reason, it should contain at least eight characters, include numbers and/or punctuation, and it should not be a word in a dictionary.

Re-type the passphrase to verify that it is correct. Once you have typed it in correctly, /etc/httpd/conf/ssl.key/server.key, the file containing your key, is created.

Note that if you do not want to type in a passphrase every time you start your secure server, you must use the following two commands instead of make genkey to create the key.

# /usr/bin/openssl genrsa 1024 > /etc/httpd/conf/ssl.key/server.key

Then, use the following command to make sure the permissions are set correctly for the file:

# chmod go-rwx /etc/httpd/conf/ssl.key/server.key

After you use the above commands to create your key, you do not need to use a passphrase to start your secure server.

* The server.key file should be owned by the root user on your system and should not be accessible to any other user. Make a backup copy of this file and keep the backup copy in a safe, secure place. You need the backup copy because if you ever lose the server.key file after using it to create your certificate request, your certificate no longer works and the CA is not able to help you. Your only option is to request (and pay for) a new certificate.

Creating a Self-Signed Certificate

Once you have a key, make sure you are in the /usr/share/ssl/certs/ directory, and type the following command:

# /usr/share/ssl/certs/make testcert

The following output is shown and you are prompted for your passphrase (unless you generated a key without a passphrase):

umask 77 ; \
/usr/bin/openssl req -new -key -set_serial num /etc/httpd/conf/ssl.key/server.key  
-x509 -days 365 -out /etc/httpd/conf/ssl.crt/server.crt
Using configuration from /usr/share/ssl/openssl.cnf
Enter pass phrase:

Next, you are asked for more information. The computer’s output and a set of inputs looks like the following (provide the correct information for your organization and host):

You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [GB]:SG

After you provide the correct information, a self-signed certificate is created in /etc/httpd/conf/ssl.crt/server.crt. Restart the secure server after generating the certificate with following the command:

# /sbin/service httpd restart

Install and Enable EPEL Repository for CentOS 7.x

The EPEL is an acronym for Extra Packages for Enterprise Linux. The EPEL repository used by the following Linux Distributions:

  • Red Hat Enterprise Linux (RHEL)
  • CentOS
  • Oracle Linux

On the Terminal,

Install EPEL Repository

# yum -y install epel-release

Refresh EPEL Repository

# yum repolist

Install Packages from EPEL Repository

# yum install -y htop

Search and install Package (E.g. htop)

# yum --disablerepo="*" --enablerepo="epel" list available | grep 'htop'

Basic CURL Commands

curl is a command line tool to transfer data to or from a server. It is able to use any of the supported protocols like HTTP, FTP, IMAP, POP3, SCP, SFTP, SMTP, TFTP, TELNET, LDAP or FILE. This tool is very useful for automation, since it is designed to work without user interaction. Furthermore, curl can transfer multiple file at once.

Basic Single URL Usage

% curl

2a. Save the Download File with a preferred file name

Save the Download File on the local machine with the name provided with the parameter.

% curl -o test.o

2b. Save the Download File

% curl -O

2c. Download Multiple Files. Just Multiple -O

% curl -O -O -O

3a. Display a Progress Meter

% curl --progress-bar -o test.o 

3b. Do not display a Progressive Bar

% curl --silent -o test.o

4 Limit Rate of Data Transfer

% curl --limit-rate 1000K -o test.o

5a Uploading a File to the FTP Server

% curl -u username:userpassword -T myfile

5b. Appending the File to the FTP Server

% curl -u username:userpassword -a -T myfile

5c Downloading the File to the File Server

% curl ftp:/ --user username:userpassword -o myCentOS79.iso

6a. Verifying SSL Certificate

% curl --cacert server.crt

6b. Ignoring SSL Certificate

% curl -k

7a Proxy Server

% curl -x proxy_name:proxy_port

7b Proxy Server which requires authentication

% curl --user username:userpassword -x proxy_name:proxy_port 

8 Sending Email

% curl --url "smtps"// --ssl-reqd --mail-from "" --mail-rcpt "" --upload-file maincontent.txt --user "" --insecure


  1. Learn to use CURL command with examples
  2. Curl command in Linux with Examples

No-Cost, Self-Supported RHEL up to 16 systems under Individual Developer Subscription for RHEL

From RHEL, “No-cost RHEL for small production workloads and customer development teams

We’re addressing this by expanding the terms of the Red Hat Developer program so that the Individual Developer subscription for RHEL can be
used in production for up to 16 systems. That’s exactly what it sounds like: for small production use cases, this is no-cost, self-supported RHEL.
You need only to sign in with a free Red Hat account (or via single sign-on through GitHub, Twitter, Facebook, and other accounts) to download
RHEL and receive updates. Nothing else is required. This isn’t a sales program and no sales representative will follow up. An option will exist within
the subscription to easily upgrade to full support, but that’s up to you.


The updated Individual Developer subscription for RHEL will be available no later than February 1, 2021.