A well-configured, performant network is essential to all organisations. In the new world of companies relying on e-commerce as their prime source of income, having IT networking systems available and responsive to customers is an absolute necessity.
Linux is the most used IT networking environment with between 80% and 90% of all internet servers running some version of Linux. This is because of the unrivaled security and stability of Linux, and its ease of operation. The many user groups are also a rich source of applications, add-ons, and mods.
Common Linux distributions include Ubuntu Linux, Red Hat, and Debian.
Linux is extremely configurable from the command line. In fact, all of Linux can be managed from the command line. Coupled with the use of scripts, this makes creating automated processes very simple.
However, from time to time, all IT networking systems fail, and the network admin needs to diagnose and fix the problem. Linux provides network admins with a range of tools at their disposal to monitor, diagnose and fix network problems. Some may be incorporated in a network management application. Sometimes it is easier or necessary to operate from a command line.
Here are 10 of the top Linux command-line admin tools:
NSlookup is a command used for DNS-related queries. It can be used to query DNS entries ina DNS server. It verifies DNS mappings, MX records, and host addresses.
It has largely been superseded by the dig command.
if there is a connectivity problem, finding out where the link is broken or is especially slow is the first step in a diagnosis. Traceroute will provide the name and device type of all devices on the route between the source and the target. It also shows the latency between steps on the route.
The mtr command is a combination of the traceroute and ping commands.
Every server has a routing table setting out the route to a common and frequently used destination. A router will use the table to find the best route for packets to a destination. The route command lists the table entries.
In some implementations route also allows the creation, editing, and deletion of entries in eh routing table.
Tracepath is very similar to the traceroute command, but does not need root privileges. Quite simply, it shows each hop in the route to a specified destination, pointing out weaknesses in the network.
Netstat is an especially useful tool. It shows statistical information about each open interface on the network. The information includes open sockets, routing tables, and other connection data.
Other variations include displaying the programs associated with each open socket, detailed port statistics, and routing table information.
Linux uses caches to store information and improve system performance. The cache is flushed periodically, but sometimes, such as after an update, needs an immediate flush.
It operates in two modes, flushing the page cache and flushing the inode and dentry caches. A
composite command allows both caches to be flushed.
ifconfig means interface configurator, and is among the most basic of Linux commands. It is used to configure an interface with an IP address, and to disable or enable it. It can be used in display mode to show basic information about the interface. The information displayed will include the IP and MAC addresses, and the MTU.
Ifconfig can also be used to assign temporary IP and Gateway addresses that are reset at the next reboot.
Iwconfig is the equivalent command for wireless interfaces.
Ifconfig is still used by many network admins but officially has been replaced by the ip command.
Ping is one of the most commonly used Linux commands. Very simply, it checks for network connectivity between two nodes. It uses the ICMP echo request to ask for an answer from the target. The output shows the average response time.
In the case of no response, this could be because there is no physical connectivity, the destination address is incorrect, or the routing table is incorrect. It may also be that the target is configured not to respond to ping requests.
Strictly speaking not a network command, lscpu returns information on CPU architecture. It shows, among other things, the CPU model, virtualization support, the number of cores and threads.
All Linux systems maintain a table of IP addresses and the MAC addresses of the device associated with the IP address. The router uses the table to link hostnames with MAC addresses.
The ARP command can be used to edit the table by adding, modifying, and deleting entries.