Category Archives: Linux - Page 9

How To Configure Local DNS Query Cache In Linux With Dnsmasq

How To Configure Local DNS Query Caching In Linux With Dnsmasq

In many Linux based distributions there does not appear to be any local DNS query caching performed by default on the client side like there is in Windows. This means that if a process on the system constantly needs to connect to some domain name it will perform a DNS lookup against the resolver defined to retrieve the IP every single time.

In this particular example instance there is a process that performs 30,000,000 DNS requests per day on average against the nameserver, we are going to significantly reduce this by configuring a local DNS cache on the server performing the excessive DNS queries.

How To Provide NFS Shares For Group Collaboration

Posted by Jarrod Farncomb on February 17, 2016 1 comment

How To Provide NFS Network Shares For Group Collaboration and Sharing

Previously we have covered how to provide NFS shares to specific clients, here we are going to expand upon this and cover how an NFS share can be shared with members in a group for collaboration purposes.

This will be done primarily with the use of set group ID (Set GID), as using this results in all files and directories created within the group share being automatically set with the same group owner as the share itself.

State Of The Linux Desktop In 2016 – Year Of The Linux Desktop?

Posted by Jarrod Farncomb on February 10, 2016 10 comments

It’s the year of the Linux desktop! A statement I’ve seen thrown around for many years now. It’s basically at the point where the running joke is that “year of the Linux desktop” is CurrentYear+1, a fantasy wonderland that remains ever so slightly out of reach.

So how is Linux to use on the desktop going into 2016? Let’s find out.

Use /proc/sys and sysctl to modify and set kernel runtime parameters

Posted by Jarrod Farncomb on February 3, 2016 1 comment

Use sysctl to modify kernel runtime parameters

The Linux kernel is optimized so that it can perform generic tasks and work well with an average workload without any modification out of the box, however you can optionally further optimize and tweak various kernel runtime parameters to increase the performance level, allowing you to squeeze out as much performance as possible.

Here we’re going to discuss the /proc/sys file system and how you can modify kernel runtime parameters to modify and tune Linux.

How To Free /boot Disk Space In Linux

Posted by Jarrod Farncomb on January 27, 2016 No comments

By default the size of a /boot partition in Linux is not that big, 512mb or so is quite a typical default. This space is used to store different versions of the Linux kernel that you have concurrently installed at the same time.

If this space fills up you may not be able to perform a kernel upgrade in future so it is important to not let it fill and free up space in /boot.

How To Configure Network Teaming In Linux

Posted by Jarrod Farncomb on January 20, 2016 19 comments

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.

Configure IPv6 Addresses And Basic Troubleshooting In Linux

Posted by Jarrod Farncomb on January 6, 2016 5 comments

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.

How To Set GNOME Display Manager Banner Message

Posted by Jarrod Farncomb on December 30, 2015 No comments

Here we cover how to add a banner message in the GNOME Display Manager (GDM), this message will display in the graphical user interface (GUI) prior to a user logging in.

Configure Squid Proxy To Forward To A Parent Proxy

Posted by Jarrod Farncomb on December 16, 2015 9 comments

Here we’re going to take a look at configuring two Squid proxy servers to forward requests from an internal network with no connectivity to the Internet out to a DMZ network and then onto the Internet if required.

The configuration will allow us to select which domains should or should not be forwarded on to the next proxy server, allowing requests that are destined for domains within the internal network to not be forwarded to the next Squid proxy, while other requests to the DMZ network or the Internet will be forwarded to the next proxy.

How To Disable USB Storage Devices In Linux

Posted by Jarrod Farncomb on December 10, 2015 9 comments

By default when you plug in an external USB storage device into a computer running Linux it will automatically mount, allowing the user to access the contents.

This behaviour can be less than ideal from a security perspective, as it can allow an attacker to copy confidential files, or allow a user to run a malicious script stored on the USB device for example.

With some simple configuration changes we can disable USB storage in Linux for unprivileged users.

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