Hello Everyone,

I just finished running a yum update on a CentOS 6.7 server and after the update was completed successfully, there are four new groups created in the /etc/group file:

video:x:39:
cdrom:x:11:
tape:x:33:
dialout:x:18:

Here's a list of the packages that were updated and installed with yum:

Feb 25 14:34:50 Updated: tzdata-2016a-2.el6.noarch
Feb 25 14:34:58 Updated: glibc-2.12-1.166.el6_7.7.x86_64
Feb 25 14:35:06 Updated: glibc-common-2.12-1.166.el6_7.7.x86_64
Feb 25 14:35:08 Updated: openssl-1.0.1e-42.el6_7.2.x86_64
Feb 25 14:35:09 Updated: chkconfig-1.3.49.3-5.el6_7.2.x86_64
Feb 25 14:35:10 Updated: libudev-147-2.63.el6_7.1.x86_64
Feb 25 14:35:10 Updated: nss-sysinit-3.19.1-8.el6_7.x86_64
Feb 25 14:35:11 Updated: nss-3.19.1-8.el6_7.x86_64
Feb 25 14:35:12 Updated: php-common-5.3.3-46.el6_7.1.x86_64
Feb 25 14:35:13 Updated: libxml2-2.7.6-20.el6_7.1.x86_64
Feb 25 14:35:14 Updated: php-cli-5.3.3-46.el6_7.1.x86_64
Feb 25 14:35:15 Updated: httpd-tools-2.2.15-47.el6.centos.3.x86_64
Feb 25 14:35:16 Updated: procps-3.2.8-35.el6_7.x86_64
Feb 25 14:35:18 Updated: initscripts-9.03.49-1.el6.centos.4.x86_64
Feb 25 14:35:21 Updated: udev-147-2.63.el6_7.1.x86_64
Feb 25 14:35:22 Updated: device-mapper-libs-1.02.95-3.el6_7.4.x86_64
Feb 25 14:35:22 Updated: device-mapper-1.02.95-3.el6_7.4.x86_64
Feb 25 14:35:23 Updated: device-mapper-event-libs-1.02.95-3.el6_7.4.x86_64
Feb 25 14:35:25 Updated: httpd-2.2.15-47.el6.centos.3.x86_64
Feb 25 14:35:26 Updated: device-mapper-event-1.02.95-3.el6_7.4.x86_64
Feb 25 14:35:27 Updated: lvm2-libs-2.02.118-3.el6_7.4.x86_64
Feb 25 14:35:28 Updated: ntpdate-4.2.6p5-5.el6.centos.4.x86_64
Feb 25 14:35:34 Updated: kernel-firmware-2.6.32-573.18.1.el6.noarch
Feb 25 14:35:36 Updated: kernel-headers-2.6.32-573.18.1.el6.x86_64
Feb 25 14:35:37 Updated: glibc-headers-2.12-1.166.el6_7.7.x86_64
Feb 25 14:35:39 Updated: selinux-policy-3.7.19-279.el6_7.8.noarch
Feb 25 14:36:06 Updated: selinux-policy-targeted-3.7.19-279.el6_7.8.noarch
Feb 25 14:36:07 Updated: glibc-devel-2.12-1.166.el6_7.7.x86_64
Feb 25 14:36:14 Installed: kernel-2.6.32-573.18.1.el6.x86_64
Feb 25 14:36:14 Updated: ntp-4.2.6p5-5.el6.centos.4.x86_64
Feb 25 14:36:15 Updated: lvm2-2.02.118-3.el6_7.4.x86_64
Feb 25 14:36:16 Updated: php-5.3.3-46.el6_7.1.x86_64
Feb 25 14:36:17 Updated: 1:mod_ssl-2.2.15-47.el6.centos.3.x86_64
Feb 25 14:36:18 Updated: nss-tools-3.19.1-8.el6_7.x86_64
Feb 25 14:36:19 Updated: kexec-tools-2.0.0-286.el6_7.1.x86_64
Feb 25 14:36:21 Updated: openssl-devel-1.0.1e-42.el6_7.2.x86_64
Feb 25 14:36:21 Updated: openssl-perl-1.0.1e-42.el6_7.2.x86_64
Feb 25 14:36:22 Updated: logrotate-3.7.8-26.el6_7.x86_64
Feb 25 14:36:23 Updated: 2:libpng-1.2.49-2.el6_7.x86_64
Feb 25 14:36:24 Updated: perl-Class-MOP-1.12-2.el6.x86_64
Feb 25 14:36:24 Updated: gnutls-2.8.5-19.el6_7.x86_64

This is strange because I updated other similar server with the same hardware and OS version and these groups weren't created. I thank you in advance for your input

udev is the culprit

Search for the patch containing "video audio cdrom tape dialout" in https://www.rpmfind.net/linux/RPM/ce...l6.x86_64.html

It's an old, old patch though. Unusual that it's just taking effect on your system now.

Bizarre. I see this patch on another server "Feb 25 14:44:04 Updated: udev-147-2.63.el6_7.1.x86_64" with no groups created