This tutorial will walk you through configuring your network configurations on CentOS 6. There are three different methods to choose from, depending on what installation type and packages you have installed. Manual configuration is done by directly modifying the configuration files. You will need to be comfortable with the command-line for this one.
CentOS / RHEL : How to change the UUID of the filesystem
However, this will give you the most flexibility and is worth learning. System Config Network is a command-line tool that presents a very basic graphical interface. This a great tool for those who just want to quickly configure the network and do not require advanced features, like interface bonding teaming. And lastly, from a Gnome desktop. This is for those trying Linux out, who have yet to venture into command-line territory, or have no interest in it at all.
This configuration is done by modifying the network configuration directly, using a text editor. This method is typical for servers and is a more advanced way of doing it. Within this file, we can specify the search domains and the name servers. The search domains are used as default suffixes when no domain is added to a hostname. The base CentOS 6 installation includes the tool by default. To install it on a minimal installation, follow these instructions. Gnome is the default environment for CentOS 6 Desktop installations.
There are plenty of alternative environments that can be installed, but being the default, this one is more widely used. Following one of the three examples above, you should now have a configured network connection.
There are more advanced configurations that can be done, like bonding connections together to increase throughput or add fault tolerance, but those subjects are too advanced for this tutorial. Skip to content Overview This tutorial will walk you through configuring your network configurations on CentOS 6. Manual Configuration This configuration is done by modifying the network configuration directly, using a text editor. The new name will be applied after your next reboot.
It only takes a minute to sign up. Ethernet cards might have supposedly unique MAC addresses, but what about virtual interfaces like aliases e. By the way, since the question is about NetworkManager and NetworkManager deals with connections, there are scenarios where you can have multiple connections for a device.
For example you have a laptop with an Ethernet card which you use both at home and at work. At home you're using only IPv4 like most home users, but at work you're using only IPv6 because the company managed to migrate to it. So you have two different connections which need different IDs, so the MAC address of the Ethernet card can't be used by itself. I can regen a UUID for nic in a second and invalidate my ifcfg-ens32 or whatever device name config file.
They seem too transient to be reliable. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Ask Question. Asked 5 years, 8 months ago. Active 3 years, 2 months ago. Viewed 35k times. Not all network interfaces are Ethernet. Active Oldest Votes. Cristian Ciupitu Cristian Ciupitu 2, 1 1 gold badge 18 18 silver badges 24 24 bronze badges.
How is the UUID in the ifcfg-eth0 file for home and work related to the device itself? So you could use the command line program uuidgen from util-linux to generate one.
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Please implement one of those solutions so even after a default installation of the uuidd-package the UUID daemon can be used properly and duplicate UUIDs can no longer be generated. Installed: uuidd. However, it's not started automatically until the next reboot, and it will need to be started automatically, as you note.
This is normal behavior - services are never started automatically as a result of installation; same is true of sshd, httpd, et al.
Comment 2 Eric Sandeen UTC Alexander, because this package does not behave any differently from other daemon packages in terms of requiring a manual start after installation, I don't consider this a bug. It's more of a policy, actually, that package installation does not automatically trigger a service start. Perhaps you can just add the service start to your provisioning scripts?
But as no configuration of the service itself is needed at all, I can only see a disadvantage by not simply starting it automatically.
28.2. UUID and Other Persistent Identifiers
Would it be possible to change the policy in that case and trigger the service start after the package installation automatically? Thanks and Regards, Alexander.Under some rare conditions, you may get a GRUB loader corruption.
Below are some of the symptoms you would see when there is a GRUB loader corruption. The GRUB menu is not shown when booting the server 2. Boot the server into rescue mode, and mount the filesystem automatically.
Please refer to the below post for booting the server in rescue mode. If not, mount it manually:. Follow the steps below when a server configured to boot from a Storage Area Network SAN using multipathed devices requires to have grub re-installed. Grub requires re-installation whenever the Master Boot Record MBR on the boot device is damaged or overwritten by other boot loaders.
It is also required in situations where the boot device changes post-installation like when the boot from SAN configuration is enabled after the server has been installed or when a single-pathed SAN boot device is reconfigured to become multipathed.
Server Fault is a question and answer site for system and network administrators. It only takes a minute to sign up. Another command that might be available and also works quite well for this is 'blkid'. It's part of the e2fsprogs package.
Examples of it's usage:. Show UUID data for all partitions in easier to read format: Note: in newer releases, blkid -L has a different meaning, and blkid -o list should be used instead. Therefore this answer is probably less helpful to the original questioner. Nevertheless I believe there's an important distinction to be noticed. To boot with the root of the file system being on a certain partition you would use the linux kernel parameter syntax of:.
In this case you can specify just the beginning of the UUID--enough to be unique. This parameter is more primitive and can be understood by the kernel earlier in its boot process. A disk holds partitions, a partition holds a file system, a file system holds directories and files.
For some set-ups and operating systems there are more layers. The same partition could hold one file system one day and another on a different day. It only exists for GPT formatted disks, but not for legacy partitioned disks. The other current answers refer to the UUID of a file system in some containing partition. If the file system is copied, as a whole, to another partition or hard disk that value remains the same. This UUID is useful in finding a moved file system. Therefore this is probably more pertinent to most people.
For fedora it appears to need.
The above seems to work on most all I have found Linux systems over many years. It may have flaws, I don't know. I would prefer to get the serial number but If anyone has a way to get the serial number without needing to be root as mine is and not installing "unusual" packages that are different in different versions of Unix I would appreciate it - always can learn something.
The purpose, BTW, is to generate a unique number per machine that cannot be modified like a disk serial number and like MAC addresses once were long ago.
Those values are generated in kernel code. You can find them pretty easily using git grep command with keywords you are interested in in your kernel source directory:. Just read its code to understand how it's done.
It boils down to code like this:. It has description and also table with explanation for each part of this number. Using that table you can decode your UUID and extract some information from it, like timestamp, etc. You can usually find it printed on some sticker on your computer. For example, for my laptop it's on the bottom. Those files are actually not real files but just an interface to kernel functions. Read about sysfs for details. So in order to "change" those files you need to edit mentioned kernel files accordingly, then rebuild the whole kernel and boot it instead of one provided by your distribution.
Also, as ChristopheVu-Brugier mentioned in comment, you can change those values in DMI table in some tricky way though. But I wouldn't recommend it.
To only get the UUID of a specific disk device for example to be used in a script you can use:. Today it helped me because there was a formatted ext2 partition and I thought it was ext3, which was causing the mount to fail.
You can see all the outputs that can be added to the -o --output with. And all the commands above ,blkid or lsblk, give this kind of information.
So now at bootfor example in rc. So how to find the new device automatically? So in this case we need a reliable manner to find what is the new device name.
Fortunately, blkid does it! To see the uuid of a hard disk partition I just boot the system up with a Linux CD and goto my computer mount, click on, the partition I want to see. The uuid number of the Linux partition will be displayed. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered.
Ask Question. Asked 9 years, 8 months ago. Active 3 months ago. Viewed k times. Stefan Lasiewski.How to skip FSCK ans SELINUX in boot-RHEL6 -RHEL7- RHEL8