rhel 7

Network Interface Name in rhel7

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Anyone who has installed rhel7 knows how annoying it is to check you network and not see eth0.  Perhaps it is just me then…  Regardless here are instructions on how to change it:

First you need to know the name of the network adapter in use, you can look in /etc/sysconfig/network-scripts/ifcfg-eno##### or run this command:

# ip addr show
Now you need to do the following:
vim /etc/sysconfig/grub
add “net.ifnames=0 biosdevname=0″ to the end of the line beginning with: GRUB_CMDLINE_LINUX, for example:
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap rhgb quiet net.ifnames=0 biosdevname=0"
Now you need to regenerate the GRUB configuration with the updated kernel parameters:
# grub2-mkconfig -o /boot/grub2/grub.cfg
Now you need to change the ‘eno##” named network scripts you identified above:
# cp -p /etc/sysconfig/network-scripts/ifcfg-eno16780032 /etc/sysconfig/network-scripts/ifcfg-eth0

Next edit the newly copied network script to change any reference to the eno### to eth0, for example:

sed -i -e 's/eno16780032/eth0/g' /etc/sysconfig/network-scripts/ifcfg-eth0

Now reboot:

# shutdown -r now

After system reboot your network interface shall be called eth0 and all will be right in the world again…

Hat tip to Angelo for most of the leg work.

Using redhat-support-tool in 10 space

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OK, Private IP space, but you should know that 10 space means private IP space.

The command redhat-support-tool is useful when working with a Red Hat support ticket. Once a ticket is opened with Red Hat your next step should be to create and attach an sosreport to the ticket. If you don’t then you will waste valuable time as their first response will be, you guessed it, please attach an sosreport. Even attaching one is no guarantee they won’t still ask as they follow the script pretty closely.

The 90% use case for using the command redhat-support-tool is adding attachments, like this:

redhat-support-tool addattachment -c CASE_NUMBER /tmp/sosreport.tar.xz

If you have not configured /root/redhat-support-tool/redhat-support-tool.conf you will be prompted for your RHN user name and password.  Since I mentioned it please note that /root/redhat-support-tool contains your configuration file and a log file.  Please note: that if you configure global setting (more on that below) those settings are stored in /etc/redhat-support-tool.conf

Back to Private IP space use.  Supposedly you can configure this using the redhat-support-tool -> config option for example:

# redhat-support-tool
Command (? for help): config proxy_url proxy.your-url.domain

OR

# redhat-support-tool
Command (? for help): config proxy_url http://proxy.your-url.domain

OR setting it globally (sets it to /etc/redhat-support-tool.conf)

# redhat-support-tool
Command (? for help): config -g proxy_url http://proxy.your-url.domain

This however doesn’t always work, here is why with an explanation, thanks to my colleague Doug B:

I figured out the redhat-support-tool issue.

– It’s always connecting to proxy via https, so you have to use “http://proxy.url.edu:80” in order to force it.
– It may conflict with an http_proxy environment variable.

Even unsetting the variable within the tool (with –unset proxy_url) didn’t seem to clear out an incorrect entry – even though nothing was in the config file!

In the end it’s easiest to just to export http_proxy=http://proxy.url.edu:80 and not modify anything within the support tool itself.

As you can see a frustrating problem, yes we could have just transferred the file and uploaded it using the webUI or from another system but what would we have learned from that?!

Again, thanks to Doug B. for working with me on this.

Here is a link (account required) to more details about the redhat-support-tool: https://access.redhat.com/articles/445443

 

yum Invalid System Credential error

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I ran across the following yum error after migrating a system from being a client of Satellite 5.6 to Satellite 6.1.  First here is the error:

# yum update
Loaded plugins: package_upload, priorities, rhnplugin, search-disabled-repos, security, subscription-manager
There was an error communicating with RHN.
RHN Satellite or RHN Classic support will be disabled.

Error Message:
    Please run rhn_register as root on this client
Error Class Code: 9
Error Class Info: Invalid System Credentials.
Explanation: 
     An error has occurred while processing your request. If this problem
     persists please enter a bug report at bugzilla.redhat.com.
     If you choose to submit the bug report, please be sure to include
     details of what you were trying to do when this error occurred and
     details on how to reproduce this problem.

Setting up Update Process
rhel-6-server-rpms                                                                                                                                                            | 2.0 kB     00:00     
rhel-6-server-satellite-tools-6.1-rpms                                                                                                                                        | 2.1 kB     00:00     
No Packages marked for Update
This left me scratching my head for a few and a quick search didn’t produce much so I thought I should document this for prosperity.
The problem was with the contents of the file /etc/yum/pluginconf.d/rhnplugin.conf
Part of my transition is running this command:
sed -i -e 's/enabled=1/enabled=0/g' /etc/yum/pluginconf.d/rhnplugin.conf
The problem was unlike all of my other systems, this file must have been edited because instead of containing “enabled=1” it contained “enabled = 1”
To correct that I modified my sed command to ignore white space:
sed -i -e 's/enabled\s*=\s*1/enabled=0/g' /etc/yum/pluginconf.d/rhnplugin.conf

More details can be found using the yum.conf man page.

Hope that is helpful.

 

Password Recovery in Redhat 7

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Forgot your password on your rhel7 server? Well there are some differences to process from rhel6. Here is how you do it.

With SELinux and systemd in the mix we have to deal with that. Here is the procedure of what needs to be done in order to recover a forgotten root password on Redhat 7 Linux:

Edit the GRUB2 boot menu and enter user single mode
Remount / partition to allow read and write
Reset the actual root password
Set entire system for SElinux relabeling after first reboot
Reboot the system from single mode

Now that we understand the procedure we can proceed with Redhat 7 password recovery.

1. Edit GRUB2 boot menu

Start your system and once you see your GRUB2 boot menu use ‘e’ key to edit your default boot item. Usually it is the first line. Once you hit the ‘e’ key, scroll down and locate a line with ‘rhgb quiet’ keywords:

locate-line-grub2-boot-menu-rhel7-linuxMove to end of the line with CTRL+E then cursor to “rhgb quiet" keywords and replace them with “init=/bin/bash" as show below:

grub2-boot-menu-rhel7-linux-single-mode-reset-password

Once you edit the boot line as show above press “CTRL + x" to start booting your RHEL 7 system into a single mode. At the end of the system boot you will enter a single mode.

 

2. Read&Write root partition remount

Once you enter a single your root partition is mounted as Read Only ro. You ca confirm it with the following command:

# mount | grep root

In order to mount our partition with Read/Write flag we use mount with a remount option as follows:

# mount -o remount,rw /

Next, confirm that the root file system is mounted Read/Write rw:

# mount | grep root

3. Change root’s password

Still in the single mode we can proceed with the actual root password recovery. To do this we use passwd command:

# passwd

You will need to enter your password twice.

4. SELinux relabeling

The additional step which needs to be taken on SELinux enables Linux system is to relabel SELinux context. If this step is ommited you will not be able to login with your new root password. The following command will ensure that the SELinux context for entire system is relabeled after reboot:

# touch /.autorelabel

5. Reboot System

The final step when resetting your lost root password on RHEL 7 linux system is to reboot. This can be done with a following command:

# exec /sbin/init

After reboot you will be able to use your new root password.