Creating a Local Yum Repository Using an ISO Image

Sometime , our server internal can not access internet . we able to  create respository local for use yum command .

1. Transfer the removable storage to the system on which you want to create a local yum repository, and copy the DVD image to a directory in a local file system.

2 . Create a suitable mount point, for example /mnt/ISO

3. use the “mount” command to mount an iso
[root@kilo ~]# mount -t iso9660 -o loop V77197-01-OracleLinux-6U7.iso /mnt/ISO/   

4 . In the /etc/yum.repos.d directory, edit the existing repository files

[OL67]
name=Oracle Linux
baseurl=file:///mnt/ISO
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY
gpgcheck=1
enabled=1

5. Clean up the yum cache

 yum clean all

6. Test that you can use yum to access the repository. 

yum repolist 

Linux ss command to monitor network connections

ss - socket statistics

In a previous tutorial we saw how to use the netstat command to get statistics on network/socket connections. However the netstat command has long been deprecated and replaced by the ss command from the iproute suite of tools.

The ss command is capable of showing more information than the netstat and is faster. The netstat command reads various /proc files to gather information. However this approach falls weak when there are lots of connections to display. This makes it slower.
The ss command gets its information directly from kernel space. The options used with the ss commands are very similar to netstat making it an easy replacement.

Linux netstat command

1. List out all connections

The first and most simple command is to list out all the current connections. Simply run the netstat command with the a option.

$ netstat -a

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 enlightened:domain      *:*                     LISTEN     
tcp        0      0 localhost:ipp           *:*                     LISTEN     
tcp        0      0 enlightened.local:54750 li240-5.members.li:http ESTABLISHED
tcp        0      0 enlightened.local:49980 del01s07-in-f14.1:https ESTABLISHED
tcp6       0      0 ip6-localhost:ipp       [::]:*                  LISTEN     
udp        0      0 enlightened:domain      *:*                                
udp        0      0 *:bootpc                *:*                                
udp        0      0 enlightened.local:ntp   *:*                                
udp        0      0 localhost:ntp           *:*     

TOP command examples on Linux to monitor processes

Linux TOP command

One of the most basic command to monitor processes on Linux is the top command. As the name suggests, it shows the top processes based on certain criterias like cpu usage or memory usage.

The processes are listed out in a list with multiple columns for details like process name, pid, user, cpu usage, memory usage.
Apart from the list of processes, the top command also shows brief stats about average system load, cpu usage and ram usage on the top.
This post shows you some very simple examples of how to use the top command to monitor processes on your linux machine or server.

Note your "top" command variant

18 commands to monitor network bandwidth on Linux server

Network monitoring on Linux

This post mentions some linux command line tools that can be used to monitor the network usage. These tools monitor the traffic flowing through network interfaces and measure the speed at which data is currently being transferred. Incoming and outgoing traffic is shown separately.

Some of the commands, show the bandwidth used by individual processes. This makes it easy to detect a process that is overusing network bandwidth.
The tools have different mechanisms of generating the traffic report. Some of the tools like nload read the "/proc/net/dev" file to get traffic stats, whereas some tools use the pcap library to capture all packets and then calculate the total size to estimate the traffic load.
Here is a list of the commands, sorted by their features.

1. Overall bandwidth - nload, bmon, slurm, bwm-ng, cbm, speedometer, netload

2. Overall bandwidth (batch style output) - vnstat, ifstat, dstat, collectl

2. Bandwidth per socket connection - iftop, iptraf, tcptrack, pktstat, netwatch, trafshow

3. Bandwidth per process - nethogs