yum-security is a plugin to the Red Hat Entreprise Linux package manager yum. It helps installing only security updates (RHSA) (as opposed to bug fixes (RHBA) or enhancements (RHEA)).
Explanation of RHSA, RHBA and RHEA advisories
RHEL 7 : yum-security is part of yum
RHEL 6 :
yum install yum-plugin-security
List all available erratas without installing them :
yum updateinfo list available
List all available security updates without installing them :
yum updateinfo list security all
yum updateinfo list sec
List of the currently installed security updates :
yum updateinfo list security installed
More examples are available in this Red Hat KB article
Quick round up of the Spacewalk client configuration files :
The main configuration file is : /etc/sysconfig/rhn/rhncfg-client.conf
This file makes use of variables whose values are located in /etc/sysconfig/rhn/up2date
The server identity in Spacewalk is located in the XML file /etc/sysconfig/rhn/systemid
Two links for an in-depth explanation regarding Red Hat backporting security fixes process as well as compatibility between Red Hat security advisories and Mitre CVEs.
Backporting Security Fixes
Red Hat and CVE compatibility
Red Hat provides free access to two databases for errata and for CVE referenced in Red Hat products :
Red Hat Product Errata database
Red Hat CVE Database
Per Fail2ban main page, Fail2ban is the de facto tool to have to monitor malicious access attempts on your server and ban source IPs if need be.
The 2 presentations presents Fail2Ban’s history and features in a very-well manner :
Fail2Ban – Keep your boxes skiddie-free
Fail2ban : from personal to community-driven
Github’s project page
Upgrade a rpm package on a couple of servers with a quick one-liner in Ansible :
ansible all -b --ask-become-pass -m yum "name=bash state=latest"
servers_list is the text file listing your servers.
Using the ANSIBLE_INVENTORY variable overrides the use of a generate inventory.
This one-liner makes use of the yum Ansible module.
Running sudo commands is possible with these options -b and –ask-become-pass
gpasswd is the right tool for it.
For instance, let’s remove user user_name from secondary group group_name :
gpasswd -d user_name group_name
To disable TLS/SSL Birthday attacks on 64-bit block ciphers (SWEET32) in Apache in CentOS 7.2.15111, remove any DES-based ciphers in your Apache ssl configuration file :
[root@localhost:~]# cat /etc/httpd/conf.d/ssl.conf
Make sure that your httpd config file syntax is OK :
[root@localhost:~]# apachectl configtest
Restart your web server :
[root@localhost:~]# systemctl restart httpd.service
Run a nmap scan with ssl-enum-ciphers script enabled :
[root@localhost:~]# nmap --script ssl-enum-ciphers -p 443 server_fqdn |grep 3DES
No DES-based ciphers should be displayed.