Update on Oct. 9, 2014: You should be aware of the possible security problems of blowfish and it is suggested not to be used. Instead, you may consider ChaCha20 as suggested by Tony Arcieri. To use this with OpenSSH, you need to specify the Ciphers in your .ssh/config files as chacha20-poly1305@openssh.com possibly with another default…
I use Emacs in terminals and start/close Emacs frequently as needed like in a file checking-editing-closing loop. However, Emacs seems take some time to start up especially some heavy modes are used. How to make Emacs start up faster? (If you just want the solution/script first, find the command in the summary section.) My solution…
Vim is a fast and handy editor on *nix systems. Like Emacs, Vim has a steep learning curve as you get constantly get new things. However, the effort deserves it as you efficiency is highly improved. Here, I summarize the tips and howtos I learned using Vim. Some previous posts on vim are tagged with…
I ever introduced seting up git server using SSH or gitosis. However, gitolite is the way to go for managing git servers if you want an lightweight authentication layer. gitolite provides many very usefull features which can control each user’s right on each branch. I set up one gitolite git server and am very happy…
Software you will need 1, Putty 2, Real VNC viewer 3, twm (lightweight desktop). On fedora (centos, redhat): sudo yum install twm (on other distros, you may need other commands, or download source code and install it). Specific steps 1, Enter your Host name and port in putty. 2, Set port forwarding in putty Tunnels….
Port forwarding (or tunnelling) is a method to forward one network traffic to another. We will introduce how to forward ports using SSH tunnel in this post. A simple example Let’s start with a simple and useful example: we want to forward local port 8080 to server:port. We can easily do this by using ssh…
The performance of Xen’s Dom0 is important for the overall system. The disk and network drivers are running on Dom0. I/O intensive guests’ workloads may consume lots Dom0′s CPU cycles. The Linux kernel calculates various network related parameters based on the amount of memory at boot time. The kernel also allocate memory for storing memory…
In Linux, we use passwd to change password, but passwd requires input from stdin to get the new password. It is common case that we may want to change the password non-interactively, such as creating new user accounts and change or set password for these accounts on a number of Linux boxes when the new…
The socks proxy I created following Proxy Using SSH Tunnel works very well on both Linux and Windows. However, when I try to configure my iPhone and iPad with iOS, I find iOS does not support socks proxy in its settings interface. I don’t know why it is not added while socks proxy is indeed…
This article is an instruction of how to use https://www.systutorials.com/proxy-using-ssh-tunnel/ on a Windows machine. The mechanism is similar as the one in https://www.systutorials.com/proxy-using-ssh-tunnel/ with “Proxy listening to localhost port only”. Download PuTTY PuTTY is the software we use here for port forwarding. Please download it following the links in https://www.systutorials.com/open-source-and-portable-ssh-scp-sftp-and-vnc-clients-for-windows-to-remote-control-linux/. Configure PuTTY and create a…
It is useful sometimes to set up a sshd server on a Windows. One example is using remote forwards tunnel to pass through the firewall. My platform is Windows XP SP3. The sshd server is sshwindows. It can be dowloaded from here: http://sshwindows.sourceforge.net/ . The version I use here is 3.8p1-1 20040709. It is really…
I frequently run some commands/scripts on a batch of servers whose IPs are already collected in a file. I usually use a simple loop and call the ssh to run these commands remotely and automatically. This operation, however, is common and can be abstracted into a separate script. Here is the script that I come…
iptables is a mechanism in Linux kernel for port forwarding, NAT, firewalls etc. In Linux distros, such as Fedora, the iptables is configured to be as a “strict” firewall that opens a limited know ports, such as 22 for SSH. However, in some network environment, such as a private cluster, the nodes are trusted and…
This is a simple tutorial for beginners to SSH to a Linux host. This is quite easy with the easy-to-use software freely available but the beginners need a tutorials to start with. Hence, I write this tutorial about how to ssh to a Linux host. This tutorial is for users on Windows. 1. Download a…
This post is a tutorial for new users to set up git and clone and use the first repository. This post introduces how to start using git for new users. This post does not introduce details of how to use git commands. Please refer to the git manual or other tutorials for how to commit,…
ssh, scp, sftp and vnc are frequently used tools (both servers and clients) on Linux. We may want to remote control a Linux box from Windows such as when we make demostration in a meeting while our work are done on the Linux box. There are lots open source SSH, SCP, SFTP and VNC clients for…
LVM’s snapshot feature enables us to duplicate an LVM backed Xen DomU in seconds inside of the same volume group. When we want to duplicate LVM backed Xen DomU from a remote server, we need to make use of LVM’s snapshot function and tools like scp and dd. Backing up the DomU is only part…
Solutions to Linux cluster construction and management such as unified account management, NFS home directory, network configurations are summarised in this post. The post is keeping updating while new solutions is added to this site. ===Account and storage management=== [[unified-linux-login-and-home-directory-using-openldap-and-nfsautomount|Unified Linux Login and Home Directory Using OpenLDAP and NFS/automount]] [[backup-linux-home-directory-using-rsync|Backup Linux Home Directory Using rsync]]…
mplayer/mencoder are powerful tools. This is a list of useful mplayer/mencoder commands. Extract the audio, convert it to PCM and write the resulting wave file to audio.wav: mplayer -vo null -hardframedrop -ao pcm:file=audio.wav video.avi Convert .wav file to .mp3 file: lame -h out.wav out.mp3 Preview a video composed of all jpeg files from the current…
Linux port forwarding is simple to do with iptables which may probably already being used as the firewall or part of the setting up a Linux gateway. In the Linux kernel, port forwarding is achieved by packet filter rules in iptables. Port forwarding Port forwarding also called “port mapping” commonly refers to the network address…