≡ Menu


X11 forwarding request failed on channel 0 Error and Solution

I am a new Linux server user. I need to tunnel X over ssh. I type the following command from OS X Unix terminal to login into far_away_machine (a centos server):

ssh -X -o options -A -p 22 user@centos-far-away-server

But, I am getting the following error on screen:

X11 forwarding request failed on channel 0
Last login: Sun Mar 23 15:58:51 2014 from

How do I fix "X11 forwarding request failed on channel 0" on Linux or Unix-like systems?
[click to continue…]

HowTo: Setup SSH Keys on a Linux / Unix System

I recently read that SSH keys provide a secure way of logging into a Linux and Unix-based server. How do I set up SSH keys on a Linux or Unix based systems? In SSH for Linux/Unix, how do I set up public key authentication?
[click to continue…]

CentOS Linux 5/6: Change OpenSSH Port Number

I am a new CentOS Linux user. How do I change default sshd tcp port # 22 to 2022 on CentOS Linux version 5/6?
[click to continue…]

OpenBSD: Reload / Restart / Stop dhcpd Server Command

I manage MS-Windows server and recently started to play with OpenBSD server. How do I reload or restart the dhcpd server on OpenBSD using shell command line option?
[click to continue…]

Change Password Using passwd Command Over SSH Based Session

I'm a new Ubutnu Linux user. I backup files to our corporate Unix backup server using the rsync command. The server only allow to upload/download files. I am unable to login to the server. How do change my password using the passwd command over ssh based session?
[click to continue…]

OpenSSH Config File Examples

How do I create and setup an OpenSSH config file to create shortcuts for servers I frequently access under Linux or Unix desktop operating systems?
[click to continue…]

OpenBSD: Mount An ISO Image Command

How do I mount an ISO image in OpenBSD operating systems using command line options?
[click to continue…]

Red Hat Linux (RHEL) 5/6: Change OpenSSH Port Number

I am a new Red Hat Enterprise Linux server sysadmin. How do I change default sshd tcp port # 22 to 3033 on RHEL v5/6? How do I modify SELinux to allow port 3033 and how do I saftly update firewall on RHEL to allow tcp port # 3033? How do I change ssh port on Redhat Linux operating system?
[click to continue…]

OpenBSD: Configure Network Interface As A Bridge / Network Switch

I have Soekris single board communication embedded computers which is optimized for low power and network usage. The server has four Ethernet ports. How do I setup IPv4 software bridge using OpenBSD operating systems so that the rest of four ports act as a network switch?
[click to continue…]

CentOS Linux: Start / Stop / Restart SSHD Command

I'm a new CentOS Linux server user. How can I start, stop, or restart the OpenSSH (SSHD) server on a CentOS Linux? How can I start SSHD on boot time on a CentOS Linux?
[click to continue…]