Tag Archives: networking

21 ss Command Examples In Linux

SS Command Examples For Linux

The Socket Statistics (ss) command is similar to netstat, in that it is used to display useful network socket information.

For some time now the netstat manual page has noted “This program is obsolete. Replacement for netstat is ss.”, so this is going to be a useful command to know how to use moving forward.

Fortunately a lot of the options are similar to the ones used by netstat, however there are a few differences as we will see.

Read more »

How To Disable The Firewall In CentOS 7 Linux

How To Disable The Firewall In CentOS 7 Linux

Default installations of the CentOS 7 Linux operating system have the firewalld firewall installed and enabled by default as a security measure, but how can we disable it?

In this quick guide we will show you how to disable both firewalld or iptables in CentOS 7 through the command line.

Read more »

How To Open A Port In CentOS 7 With Firewalld

How To Open Port In Firewalld For CentOS 7 Linux

This tutorial will walk you through opening a port in the default firewall in CentOS 7, firewalld.

You will see that while we can manually open a specific port, it is often easier and beneficial to allow based on predefined services instead.

Read more »

How To Install Ifconfig In CentOS 7

How To Install Ifconfig Command For CentOS 7 Linux

By default in CentOS 7 minimal the ifconfig command is not available, and for good reason, it’s considered deprecated and has been replaced by the ip command.

Regardless, if you really can’t get by without ifconfig, here’s how you can install it.

Read more »

How To Display Routing Table In Linux

How To Show Routing Table In Linux

The routing table is used to show you where various different network subnets will be routed to. Here are three different commands that you can use to print out the routing table in Linux.

Read more »

How To Configure Network Teaming In Linux

Configure Network Teaming

In Linux it is possible to aggregate multiple network links together into a single logical link which can either increase network throughput or redundancy. For example we can assign an IP address to a group of two network interfaces to double our throughput, or reserve one interface for backup purposes so if the first one fails we can fail over.

Here we’re going to cover how to create and configure a network team with two different network interfaces.

Read more »

Configure IPv6 Addresses And Basic Troubleshooting In Linux

How To Configure And Troubleshoot IPv6 Addresses In Linux

In the past many system administrators have simply resorted to disabling IPv6 rather than properly configuring it, continuing to rely on the older IPv4 which has worked just fine for a very long time. As the IPv4 address space has since become exhausted, administrators are starting to slowly take up IPv6 out of necessity.

Here we’re going to cover how to configure IPv6 addressing in Linux and provide some basic tips and advice for troubleshooting IPv6 network issues.

Read more »

Use SELinux Port Labeling To Allow Services To Use Non-Standard Ports

SELinux Ports

By default SELinux policy defines the ports that a particular service is allowed bind to and make use of with port labeling. This increases system security by preventing random services or malicious code from being able to bind to a well known defined port that may otherwise be used by a legitimate service.

In order to change a service to use a non standard port we must change SELinux policy and specify the SELinux port types that are allowed to use specific ports.

Read more »

How To Create Static Routes to Route IP Traffic

Static Route

By default all network traffic will normally be configured to route via the default gateway, that is the router attached to the network interface. It may not always be the case that you want all traffic to take the same path, in these instances we can set additional static routes that will forward specific traffic out of a different interface rather than the default gateway. This may be required if you need to be able to reach a particular network that your default gateway router does not know about.

Here we’re going to cover how to configure a static route in Linux.
Read more »

How To Enable Telnet Client in Windows Server 2016

By default the telnet client in Microsoft’s Windows operating systems is disabled, this is unfortunate as it is an extremely useful tool which can be used for testing TCP connectivity to external hosts on a specified port.

This is great when you’re trying to troubleshoot network connectivity problems, for example, say we have a web server which should be listening on port 80 to serve HTTP traffic but we are not able to load a web page, by using telnet to connect to the web server on port 80 we can verify the connectivity.

It may be that the connectivity is fine but there is a problem with the web server, or that the web server is stopped and the port is not listening at all, for instance. With telnet we can get a better understanding of what’s going on.

Read more »