Tag Archives: cent os

How to add new brick to replicated GlusterFS volume on Linux

How to add new brick to replicated GlusterFS volume on Linux
I have a three server replicated volume setup (scalable network filesystem for cloud and VMs). I need to add one more server. How do I add a new a new brick to an existing replicated volume on a Debian or Ubuntu/CentOS Linux?
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How to test the network speed/throughput between two Linux servers

How to test the network speed/throughput between two Linux servers

I have setup total four servers in cloud based data center. They run either CentOS or Ubuntu Linux. I need to make sure clustered file system performance is reasonable as my servers shared with other users. How do I check the speed between the two Linux servers using command line options for private LAN/VLAN?
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How to install the latest/stable version of Linux kernel on Ubuntu Linux using apt-get

How to install the latest/stable version of Linux kernel on Ubuntu Linux using apt-get

I read your tutorial about compiling a stable version of the Linux kernel on a Ubuntu/Debian Linux. I wanted to install the same using apt-get command. How can I install the latest (mainline) Linux kernel on Ubuntu Linux?
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Increase your Linux server Internet speed with TCP BBR congestion control

Increase your Linux server Internet speed with TCP BBR congestion control
I recently read that TCP BBR has significantly increased throughput and reduced latency for connections on Google’s internal backbone networks and google.com and YouTube Web servers throughput by 4 percent on average globally – and by more than 14 percent in some countries. The TCP BBR patch needs to be applied to the Linux kernel. The first public release of BBR was here, in September 2016. The patch is available to any one to download and install. Another option is using Google Cloud Platform (GCP). GCP by default turned on to use a cutting-edge new congestion control algorithm named TCP BBR.
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Download of The Day: Fedora Linux 26

Download of The Day: Fedora Linux 26
Fedora 26 with KDEFedora Linux version 26.0 has been released ( jump to download ) after many months of constant development and available for download in various media format. Fedora 26 is a free and open source operating system includes various new features such as GCC 7, Golang 1.8, Python 3.6, DNF 2.0, OpenSSL 1.1.0 and more. Fedora 26 runs on both ARM servers and desktop boards too.
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How to fix IPMI KVM JAVA BMCMD5withRSA and is treated as unsigned error

How to fix IPMI KVM JAVA BMCMD5withRSA and is treated as unsigned error
Like any good sysadmin, I kept my servers and desktop side up to date and patched all the time. However, recent Java updates have broken my IPMI KVM Java Applets on Dell, IBM, HP, Supermicro and FreeNAS mini servers. You will get an error that read as follows:

Unsigned application requesting unrestricted access to system. The following resource is signed with a weak signature algorithm MD5withRSA and is treated as unsigned.

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Why port 80 (HTTP) reported as open by nmap when it is closed?

Why port 80 (HTTP) reported as open by nmap when it is closed?
Why are some ports reported as open by nmap?
I recently setup a small server which is running Debian 9. The purpose of this machine is to run OpenVPN server on port 443 to bypass censorship. It runs the following services and nothing else:

  1. Squid on private IP belongs to VPN pool (10.8.0.1:3128)
  2. SSH on private IP belongs to VPN pool (10.8.0.1:22)
  3. DNS resolver on private IP belongs to VPN pool (10.8.0.1:53)
  4. OpneVPN on public IP port 443 (server_public_ip_address:443)

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