These steps should be similar across Red Hat type distros.
Before we proceed, lets stop SNMP
sudo systemctl stop snmpd
Disable SNMP Versions 1 and 2c
First we are going to disable SNMP v1 and v2c
You can manually edit the /etc/snmp/snmpd.conf file and comment out or delete every line starting with com2sec, group, access. Or you can run the following sed commands to change it for you.
sudo sed -i 's/^com2sec/# com2sec/g' /etc/snmp/snmpd.conf sudo sed -i 's/^group/# group/g' /etc/snmp/snmpd.conf sudo sed -i 's/^access/# access/g' /etc/snmp/snmpd.conf
If you are running a firewall, you will need to allow an exception for SNMP, UDP port 161. You may also need to allow an SELinux exception. Check out the last portion of both these articles.
Bob has a computer running Fedora. When he installed Fedora he didn’t setup the root password and locked the root account. That is best practice. Right? Then one day he goes to upgrade to the latest version of Fedora and types in
sudo dnf update
and is greeted with
sudoers. This incident will be reported.
What happened? I had access before? Bob thinks to himself. Seems like I am not in the wheel group anymore. Bob being a smart person decides to attempt recovery mode. He’ll boot up and just readd his user to the wheel group.
Recovery mode starts up and then fails due to the root account being locked. What?!
Bob then starts talking to himself as he is in need of some expert advice. What other options do I have. I know! He runs to find his handy dandy Live Fedora pen drive. Plugs it in and boots up into a live version of Fedora. Now I can mount and access the main drive.
But wait, I can’t run “usermod -G wheel bob” because that will only affect the Live System. I could chroot into the drive. That would require mounting some extra mount points. Is there a faster way? We could maybe edit the /etc/group and add “wheel:x:10:bob”. That should add bob back to the wheel group. Right?
Wait, what about the sudoers file. We are normally supposed to use “sudo visudo” command to modify the file. Let’s check the file and see if we can just manually edit it.
$ stat -c "%n %a" /etc/sudoers
/etc/sudoers 440
$
Permissions on /etc/sudoers file
Hmm, okay I am going to need to change permissions to save the file. Let’s chmod that to 644 temporarily
$ sudo chmod 644 /etc/sudoers
Alright now I should be able to edit it.
$ sudo vi /etc/sudoers
Okay, now I need to explicitly give myself permission to use sudo. Where is that line. Ah-ha!
root ALL=(ALL) ALL
Lets duplicate that with yy and p, replace root with my username.
root ALL=(ALL) ALL
bob ALL=(ALL) ALL
Save that with esc then :wq enter
Now change the file permissions back
sudo chmod 400 /etc/sudoers
Reboot the system and now lets login and test sudo.
$ sudo whoami
root
Success!
Bob, satisfied that the problem is resolved, rewards himself by getting a sandwich.
If you are in recovery mode on Fedora, add –no-dbus right after the snapper command. e.g.
snapper --no-dbus list
You can use the diff command to list the changes that happened between snapshots.
snapper --no-dbus diff 108..109
And to undo a change or all the changes between a snapshot, do the following. Where 108..109 are all the changes you want to remove. So essentially going back to snapshot 108.
By default Linux and OLED displays don’t really want to play well together. icc-brightness is a handy utility that resolves the problem, but all the instructions I found online were for Ubuntu/Debian based distributions.
We now need a user to connect to the Samba share with. You can use the commands below to to create a new user.
pdbedit only configures a current Linux system user for Samba. You can skip creating a new Linux user, but only if there is one already created that you can use.
You can now test to see if the share works. Open up Windows Explorer. Type in the IP address of the server and connect.
\\ip-address\sambaUser
It should prompt you for a login. Enter the user and password you set up.
Connecting to Fedora Samba/CIFS server
If it loads, then congratulations! You have successfully setup a Samba/CIFS Share on Fedora Server. Create new directories or files or whatever else you need.
Successfully Connected to Fedora Samba/CIFS Server
Check out the following links for more information about setting up Samba.
There are a few different ways to view RAID information on Fedora. Here are two commands that can help.
1. Print Mdadm config
You can copy and past the following command to print the mdadm configuration.
cat /etc/mdadm.conf
It should return something similar to the following.
$ cat /etc/mdadm.conf
# mdadm.conf written out by anacondaMAILADDR root
AUTO +imsm +1.x -all
ARRAY /dev/md/Boot level=raid0 num-devices=6 UUID=21ce258a:015d0dd4:90d5b80e:ab04b7f7
ARRAY /dev/md/Root level=raid0 num-devices=6 UUID=4be32ad0:f3aa77bd:139d749d:4a6aab60
We see from the above output that we have two raid arrays. Both RAID 0 over 6 drives.
2. Print mdstats
You can show the mdstats by running
cat /proc/mdstat
Should get output similar to the following.
$ cat /proc/mdstat
Personalities : [raid0]
md126 : active raid0 sdc2[0] sdf2[5] sde2[4] sdd2[1] sda2[2] sdb2[3]
5856552960 blocks super 1.2 512k chunks
md127 : active raid0 sdc1[0] sdf1[5] sde1[4] sdd1[1] sdb1[3] sda1[2]
3133440 blocks super 1.2 512k chunks
unused devices:
This shows us the RAID size. About 5TB on one and 3GB on the other. The 3GB is used for the boot partition.
Other Notes
Apparently there is a difference between “mdadm” and “dm-raid” Mdadm is for managing and creating software raids, while dm-raid interacts if a device like a laptop has a “fake RAID”
