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How to install OpenSSL and mod ssl First need to install the openssl and mod ssl and then will generating the certificate to be used. Open a terminal prompt and issue the following command  [root@Centos7 conf.d]# yum install mod_ssl Loaded plugins: fastestmirror, langpacks Loading mirror speeds from cached hostfile  * base: mirror.nbrc.ac.in  * epel: kartolo.sby.datautama.net.id  * extras: mirror.nbrc.ac.in Resolving Dependencies --> Running transaction check ---> Package mod_ssl.x86_64 1:2.4.6-67.el7.centos.5 will be installed --> Finished Dependency Resolution Dependencies Resolved ========================================================================  Package                     Arch                       Version                                     Repository                   Size ======================================================================== Installing:  mod_ssl                     x86_

How to install xrdp on CentOS 7 / RHEL 7 1. First Install Gnome on CentOS 7 2. Install and configure EPEL repository. [root@Centos7 system]# yum install epel-release Loaded plugins: fastestmirror, langpacks base                                                                                                           | 3.6 kB  00:00:00 extras                                                                                                         | 3.4 kB  00:00:00 updates                                                                                                        | 3.4 kB  00:00:00 updates/7/x86_64/primary_db                                                                                    | 2.7 MB  00:00:07 Loading mirror speeds from cached hostfile  * base: ftp.iitm.ac.in  * extras: ftp.iitm.ac.in  * updates: ftp.iitm.ac.in Resolving Dependencies --> Running transaction check ---> Package epel-release.noarch 0:7-9 will be installed --> Finished D

While configuration postfix authentication getting the error status=deferred (delivery temporarily suspended: connect to smtp.office365.com[2603:1026:3:ca::2]:587: Network is unreachable) its because of you were not using IPv6/ wrong settings for ipv6. You can either use IPv4, or correct your IPv6 settings. [root@mailserver postfix]# netstat -nutlap | grep 25 tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      3956/master tcp        0      0 127.0.0.1:38442         127.0.0.1:3306          ESTABLISHED 2596/httpd [root@mailserver postfix]# vi /etc/postfix/main.cf [root@mailserver postfix]# systemctl restart postfix [root@mailserver postfix]# netstat -nutlap | grep 25 tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      4079/master tcp        0      0 127.0.0.1:38442         127.0.0.1:3306          ESTABLISHED 2596/httpd tcp6       0      0 :::25                   :::*                    LISTEN      407

Getting the error while running the sudo -s to become root sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set 1.Login the server using root and change the permission of /usr/bin/sudo chmod 4755 /usr/bin/sudo 2. if you do not have root password then reboot the server on single usermode and run these commands. mount -o remount,rw /dev/mapper/lv_root / chown root:root /usr/bin/sudo chmod 4755 /usr/bin/sudo restart