Linux Admin Zone

In any Red Hat based (RHEL/CentOS/Fedora) Server, change time zone to PST/PDT quickly:

# mv /etc/localtime /etc/localtime.old && ln -s /usr/share/zoneinfo/PST8PDT /etc/localtime

or set zone to IST:
# mv /etc/localtime /etc/localtime.old && ln -s /usr/share/zoneinfo/Calcutta /etc/localtime

or Set the TZ environment variable for quick display time according to preferred Time Zone:
# export TZ=America/Los_Angeles
and then view the output of date command.

or If you have the utility rdate, update the current system time by executing
# rdate -s pool.ntp.org

or You can execute ‘system-config-date’ for setting up date/time and time zone:
# system-config-date

By viewing this error while using your ftp server, you may get the impression of some bug/problem in your ftp server. This is exactly what happened in the early morning when I got call that vsftpd server in one of the Amazon EC2 server stopped working. When trying to transfer a file it’s showing something like this:

Error: Could not write to socket: Broken pipe
Unable to download file xxxx

In first, I checked the config of vsftpd, and restarted it. It’s working fine. Then got the clue from “unable to download file” messages which indicates that ftp server is not able to write/download file. When I checked the space:

ejabberd, as described in its home page:
” ejabberd is a distributed, fault-tolerant technology that allows the creation of large-scale instant messaging applications.The server can reliably support thousands of simultaneous users on a single node and has been designed to provide exceptional standards of fault tolerance. As an open source technology, based on industry-standards, ejabberd can be used to build bespoke solutions very cost effectively.”

Describing here Instructions I followed to install and configure ejabberd in CentOS 5:

Step 1. Download the current stable version of ejabberd from its official site. While writing this article the stable version was 2.0.6. I’ve download the binary file for 32 bit Linux machine and uncompress it:

SSH has a wonderful feature called SSH Port Forwarding, also known as SSH Tunneling, which allows you to establish a secure SSH session and then tunnel arbitrary TCP connections through it. Tunnels can be created at any time, with almost no effort and no programming, which makes them very appealing.

Here I’ll illustrate it using an example. Suppose you have installed and configured Jabber Instant Messaging Server (check out to do that on this site here). You found later that in the Server machine, there’s no GUI available and you need to access its graphical web admin interface. In this case, you can easily forward port from Server machine to your own PC to access the admin interface. You might know that ejabberd (Jabber Server) web admin interface is available on port 5280.

When installing perl Net::SFTP module in CentOS 5 box:

# perl -MCPAN -e 'install Net::SSH::Perl'

It got stuck at:

t/01-compile.t…..ok
t/02-buffer.t……ok
t/03-packet.t……1/10

then I tried installation with force so that it can skip tests if any of them failed:

# perl -MCPAN -e 'force install Net::SSH::Perl'

The module seems installed ok but while using in a script, error occured:
Can’t locate Net/SSH/Perl/Buffer.pm in @INC …

that means, the module still not installed/configured properly. To get it done, I searched for rpms and found rpmforge repository http://dag.wieers.com/rpm/packages/rpmforge-release/ have all the sufficient rpms: