The [nixcmd name="cat"] (short for concatenate) is one of the most frequently used flexible commands on Linux, Apple MacOS X, *BSD (FreeBSD / OpenBSD / NetBSD), Unix-like operating systems. It is useful to display text files on screen, copy text files, combine text files, create new text files and more. If you cat command with colours, try ccat app.
Let us face it we all make mistakes at the command line. Typos? Wrong options? Forget to add sudo? The list goes on. There is a neat little app called thefuck which corrects your previous Linux and Unix command line mistakes.
Recently I created a simple shell script called backup.sh in /root/scripts directory to just backup MySQL database and dumped it to /nfs/mysql/ directory. I put a file (more like used the ln command to create a soft link ) in /etc/cron.hourly/ and it doesn’t run. There was no error in systemd log or cron log. Why is my cron job was not working, and here is how I troubleshoot it.
From the announcement mailing list:
I’ve just uploaded a version of OpenSSL to unstable that disables the TLS 1.0 and 1.1 protocol. This currently leaves TLS 1.2 as the only supported SSL/TLS protocol version.
This will likely break certain things that for whatever reason still don’t support TLS 1.2. I strongly suggest that if it’s not supported that you add support for it, or get the other side to add support for it.
OpenSSL made a release 5 years ago that supported TLS 1.2. The current support of the server side seems to be around 90%. I hope that by the time Buster releases the support for TLS 1.2 will be high enough that I don’t need to enable them again.
ls is a command to show files in Linux and Unix-like operating systems. A ls command first appeared in a version of AT&T UNIX as well as in Multics. BSD and GNU Coreutils package provides the ls command with minor syntax changes. There is now third alternative named exa. It is a modern replacement for ls.
Groupware (also known as “Collaborative software”) is nothing but an app that helps users in everyday tasks such as calendar/scheduling, address books, email, forums, mailing lists, IM, wiki and more. The use of collaborative software in the work space creates a collaborative working environment. You can synchronize and share your files and photos easily using your hardware while maintaining privacy and security. Here is a list of 5 of them that you must know.
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.
Fedora 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.
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.
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:
- Squid on private IP belongs to VPN pool (10.8.0.1:3128)
- SSH on private IP belongs to VPN pool (10.8.0.1:22)
- DNS resolver on private IP belongs to VPN pool (10.8.0.1:53)
- OpneVPN on public IP port 443 (server_public_ip_address:443)