Introduction As we know, network subsystems are important in computer systems since they are I/O systems and need to be optimized with many algorithms and skills. This article will introduce how QEMU/KVM [2] network part works. In order to put everything simple and easy to understand, we will begin with several examples and then understand […]
Posts on Network
Network-related posts.
22 posts in total.
How to Change Linux Account Password Through SSH: A Beginners’ Tutorial
People are sometimes given access to Linux/Unix and asked to change their initial passwords. But for beginners, changing a Linux/Unix password is not an easy task, especially when there is only SSH log on allowed to the Linux/Unix server. This post introduces how to change password of user USER on host HOST remotely using SSH. […]
How to Set the Static IP Address Using CLI in Fedora/CentOS Linux
How to set the static IP address for CentOS 7/Fedora 22+ is introduced in this post. Here, we assume the Linux is using NetworkManager to manage the network. All steps are done as root. Find the interface you want to set the address ∞ Command ifconfig -a lists all interfaces. Find the interface name to […]
How to Keep Linux SSH Session Alive from Disconnecting – Server and Client Side Fixes
SSH is a very common tool for Linux/Unix platforms. One annoying problem when using SSH is that the connection may get disconnected if the SSH connection is idle for some time under common configurations. Users may run an infinite loop like while true; do uptime; sleep 30; done when there is no work to be […]
Blocking JavaScripts from a Site in Chrome in 2 Easy Steps
You may be aware of the GitHub’s largest DDoS attack in history on Mar. 27, 2015 (some context, technical details, and discussions): We've been under continuous DDoS attack for 24+ hours. The attack is evolving, and we're all hands on deck mitigating. — GitHub Status (@githubstatus) March 27, 2015 One important technique when facing this […]
Free VPNs for iPhone Users: OpenVPN + Ovpn Spider
VPNs are useful for testing viewing webpages from a remote location or visiting blocked websites. In this post, I will introduce a method for finding and using free VPNs on iPhone. Note that the VPNs are free and the providers are not identified. Hence, only use this method for visiting public webpages or keeping visiting […]
iPhone Connecting to Internet Using Windows PC’s Network through USB Cable
Note that this was only tested on certain combinations like this (Windows 7 with iOS 8), this (Windows 7 with iOS 7), this and this (Windows 7 with iOS 9.3.2 (iphone 6s)). Windows 7 seems a possible Windows OS that can work. Recently, I tested it on Windows 8 and iOS 9. Unfortunately, it did […]
Lazy Linux Admins Going to Server Rooms Less: Forced Reboot, Auto Reboot after Kernel Panic and Email Notification after Reboot
Having to go the the server room to reset servers is the most headache thing for admins managing a cluster of Linux servers in a remote site. Either you can ping the server but can not ssh to it, or you even can not ping it. There are various reasons that may cause a Linux […]
MPlayer over SSH to Play Movie from Remote Host
MPlayer is a great movie player. SSH is a great tool to connect and transfer data over the network securely. Combining these 2 great tools together will be greater. You may already has a small server storing some movies or videos or music and playing them on your laptop will be convenient. In this post, […]
Git through SSH Tunnel as Proxy
git is a great tool and it is common to have a git server over SSH possibly managed by gitolite. However, there are situations that we can not directly connect to the git server but be able to SSH to another node that can connect to the git server. The git server may allow only […]
Improving ssh/scp Performance by Choosing Suitable Ciphers
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 […]
How to Set Up A Gitolite Git Server – A Ten-Minute Tutorial
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 […]
Connecting to Remote Servers by VNC on Windows
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 […]
Fixing Ports Used by NFSv3 Server
The ports used by NFS server can be dynamically assigned by rpbind to any higher number. We need to fix the ports used by NFS server to configure firewall or port forwarding mechanism. The ports used by NFS server and how to fix these ports will be introduced in this post. There are seven ports […]
How to Configure iOS to Use Socks Proxy over SSH with a Linux/Unix Host
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 […]
Flushing iptables on Fedora
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 […]
Disabling IPv6 on Fedora 17 Linux
IPv6 is enabled by default on most Linux distros. However, IPv6 is not used most of time (at least in my case). This post introduces how to disable IPv6 support on Linux (newer Kernel versions, such as in Fedora 17). IPv6 on Linux can be easily configured via sysctrl. Add these lines to /etc/sysctl.conf: net.ipv6.conf.all.disable_ipv6=1 […]
Wireless, 3G and 2G Network Speed
I get wireless, 3G and 2G network connection via my iPhone. I tested the network speed of a wireless, 3G and 2G network possible from my iPhone using the App from OFCA. Wifi of sMobileNet network in HKUST: 25604 kbps: 3G network from a carrier in Hong Kong: 2776 kbps: 2G network from a carrier […]
Changing Hostname of Fedora Linux
Different Linux distros have different method to set the hostname. On Fedora Linux, it is quite simple. On newer Fedora releases ∞ At least from Fedora 19 (sorry, no sure the exact earliest version): You need to edit the file /etc/hostname which just contains the hostname. On older Fedora releases ∞ Sorry, I do not […]
Installing ns-2 and ns-3 on Fedora Linux
ns is a discrete-event network simulator targeted primarily for research and educational use. There are two version of ns, ns-2 and ns-3, which are quite different with each other in the implementation and method to use them. In this post, we introduce how to install ns-2 and ns-3 on Fedora Linux 15. Install ns-2.34 on […]
