Running to the end of CentOS ?

CentOS it's use by most IT production, because it's a derivative of RHEL, a tested, stable and reliable GNU/Linux OS.

Today 2020/12/08, they announce us that #CentOS becomes a derivative of Fedora and will be an upstream for future #RHEL, a "beta" version of #RHEL (who want to use it in production?). https://blog.centos.org/2020/12/future-is-centos-stream/ (IBM effect ?)

This decision will have serious impact on IT's OPEX, since 2022.

Logically for the same OS reliability and compatibility, you have to move from CentOS to RHEL. And this for the end of 2021 (if you use CentOS8 in production). That means buy more subscriptions, because of the "all or nothing" principle of Red Hat subscription, that say: "if a customer has active Red Hat subscriptions, they are still required to maintain a subscription for each instance of Red Hat Enterprise product in the environment."

At another side, we have to add the cost of migrating from CentOS to another distro, even if it's RHEL or a rebuild like Oracle Linux (this last have already surf on this announcement, by proposing a fast switching https://linux.oracle.com/switch/centos/). For sure, there will be opportunities for SysAdmin between 2021 from 2022.

Thank you to the CentOS teams, for the work over the years.
Hey #debian are you there?

PS: For the most reckless, you can sign a petition there https://www.change.org/p/centos-governing-board-do-not-destroy-centos-by-using-it-as-a-rhel-upstream

MSSQL Server on Linux (CentOS/RHEL)

Quick mssql-server installation on RHEL/CentOS.
You need at least 3.5Gb of RAM.

wget https://packages.microsoft.com/config/rhel/7/mssql-server.repo -O /etc/yum.repos.d/mssql-server.repo &&
yum install mssql-server -y && export SA_PASSWORD="Y0urP@ssw0rd" && /opt/mssql/bin/mssql-conf setup accept-eula && firewall-cmd --zone=public --add-port=1433/tcp --permanent && firewall-cmd --reload && wget https://packages.microsoft.com/config/rhel/7/prod.repo -O /etc/yum.repos.d/mssql-tools.repo && yum install mssql-tools unixODBC-devel

This will download the repository, install mssql-server, set the default password for SA account, setup mssql-server, open the accessing default port for mssql-server tcp/1433 and install mssql-tools.

You can use a remote management client like DBeaver (Linux & Windows) or SqlDbx.

http://dbeaver.jkiss.org/download/
http://www.sqldbx.com/personal_edition.html

Redirect SQUID request to another proxy

To allow acces to a corporate or public proxy's ressources via a local squid proxy, we just have activate the "cache_peer" option of Squid (a libre proxy caching server).

#Install Squid package: 
yum install -y squid
systemctl enable squid.service
systemctl start squid.service

echo "cache_peer proxy.enterprise.local 8080 0 no-digest" >> /etc/squid/squid.conf
systemctl restart squid.service

See Squid documentation in "/usr/share/doc/squid/squid.conf.documented".

Mount a NFS share on Windows 7

Server: Linux server, nfs01.corp.local
          NFS share directory : /provisoire

Client : Windows 7

Open the command line interface (cmd) with admin privileges and type:

Start nfs client service:
nfsadmin client start

Mount the NFS share directory to a drive letter:
mount nfs01.corp.local:/provisoire G:

Mount options here : https://technet.microsoft.com/en-us/library/cc754350.aspx

Davmail - Use your favorite client mail with MS Exchange

Many companies are using MS Exchange as mail server, with it's client MS Outlook. And when you are in heterogeneous operating system environment or when you're not fan of Outlook, it become difficult to connect another mail client like Thunderbird on MS Exchange's proprietary protocols like Webdav and OWA.
Fortunately, it exist a Libre Software called DavMail, that I use since 2 years with Thunderbird at work.

The main features can be seen on the picture below (source: DavMail website):

Davmail can be run as server or local mode; we will use the local mode configuration, with the latest version 4.7.0 and the email client Thunderbird.

Installation
Prerequisite: Java (jre)
-Download davmail package for Linux installation:
$ wget -O /tmp/davmail.tar.gz http://downloads.sourceforge.net/project/davmail/davmail/4.7.0/davmail-linux-x86_64-4.7.0-2408.tgz?r=http%3A%2F%2Fsourceforge.net%2Fprojects%2Fdavmail%2Ffiles%2Fdavmail%2F4.7.0%2F&ts=1447659863&use_mirror=liquidtelecom

-Extract the package:
$ tar xzvpf /tmp/davmail.tar.gz -C /opt

-Create a link, to facilitate upgrade:
$ ln -sf /opt/davmail-linux-x86_64-4.7.0-2408 /opt/davmail

-Launch davmail:
$ nohup /opt/davmail/davmail.sh &  #You can automate this

- Configure davmail to act as gateway for your Exchange server:

-Configure Thunderbird:
File > New > Existing email account

Click on "Manual config" button

 -Accept to not use encryption, for local configuration It's not an issue because of the local communication between Thunderbird and DavMail

Configure automatic launching

$gnome-session-properties

It's all folk!!!

You can also configure calendar, directory (address book) and more; go the davmail's documentations  website: http://davmail.sourceforge.net/

Get HBA WWN on CentOS Linux

New server with FC-HBAs, witch have to be connect to a SAN-Fabric ?

Get WWPN (Word Wide Port Name)
2 HBA, with 2 ports represent by a host number.

# lspci | grep HBA
05:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
05:00.1 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
08:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
08:00.1 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)

#cat /sys/class/fc_host/host*/port_name

0x500143802421ff25
0x500143802421ff27
0x500143802422010d
0x500143802422010f

$grep '0x' /sys/class/fc_host/host*/port_name 

/sys/class/fc_host/host3/port_name:0x500143802421ff25

/sys/class/fc_host/host4/port_name:0x500143802421ff27

/sys/class/fc_host/host5/port_name:0x500143802422010d

/sys/class/fc_host/host6/port_name:0x500143802422010f

Get  Fabric WWNN (Node Name)

# grep '0x' /sys/class/fc_host/host*/fabric_name 
/sys/class/fc_host/host3/fabric_name:0x100000051ec624f6
/sys/class/fc_host/host4/fabric_name:0x100000051ecc4c2a
/sys/class/fc_host/host5/fabric_name:0x100000051ecc4c2a
/sys/class/fc_host/host6/fabric_name:0x100000051ec624f6

After the zoning, we can get the remote node/port name of equipment with who we can communicate:

#cat /sys/class/fc_remote_ports/rport-*/node_name

Parallelize Rsync


1- Sync the directory tree
rsync -a -f"+ */" -f"- *" source/ destination/
2- Parallise rsync (Multiple thread)
cd $SOURCEDIR; find . -type f | xargs -n1 -P$THREADS -I% rsync -az % /$DESTDIR/%