Tag: linux

SNMP V3 on Ubuntu

March 4, 2019 / / 0 Comments

We will be installing 3 packages to get SNMP up and running on Linux.

apt install snmpd snmp libsnmp-dev

OR

yum -y install net-snmp net-snmp-utils    (if you are running yum)

Copy the default snmpd config file for backup purposes ( if you want to )

cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak

Empty the file out by doing the below

cat /dev/null > /etc/snmp/snmpd.conf

Stop the running service of snmpd by issuing the command

systemctl stop snmpd

Create your read only user account for SNMP V3. Replace “SUPERPASSWORD” and “USERNAME” with your required information

net-snmp-create-v3-user -ro -A SUPERPASSWORD -a SHA -X SUPERPASSWORD -x AES USERNAME

Now make the service start on bootup 

systemctl enable snmpd

Start the service!

systemctl start snmpd

Find the DNS being used on linux

November 27, 2018 / / 0 Comments

This is useful when troubleshooting some network related issues and you need to find which DNS servers are being used. Since resolv.conf is not really used much anymore, it’s most likely that your DNS settings are set in the NIC configuration file, which is located at /etc/network/interfaces. 

You can also print which DNS is being used on a per interface basis by doing the below – 

Identify the NIC you want to use by using 

ifconfig

Once the names of the NIC’s have been printed, find the one you want and issue this command 

nmcli device show <INTERFACE NAME> | grep IP4.DNS

Obviously replace the “<INTERFACE NAME>” with you know what.

Expanding disks in Linux

October 21, 2018 / / 0 Comments

So expanding disks in Linux seems to be somewhat of a headache sometimes. The easiest method I have found is once you have increased the space via your hypervisor, you will need to expand the disk by booting into a live ISO and using the partition manager there. Once that is done, apply the changes, reboot and expand the drive from inside the OS.

You will want to use the below commands to find the name of the volume – 

fdisk -l
df -h

Afterwards, you can use the below command to add the newly added free space to your volume – 

lvextend -r -l +100%FREE  /dev/mapper/***VOLUMEGOESHERE***