Where are the root dns servers located ?

Thanks for the concern, but there are more than 13 root servers in the world, and we are very well protected against the DOS attack. 6 of the 13 root servers are mirrored using Anycast technology to loadbalance between multiple servers. The F Root server itself has about 37 mirrors in the world.


ssh tunnelling

To Create a local ssh tunnel on your machine (port 1234 – example) to the POP3 server’s port 110. You will need to be the root user to bind to “privileged” ports

ssh -f -N -L 1234:localhost:110 user@POP3_server

Test the tunnel.
telnet localhost 1234
You should see the POP3 server’s banner information.

Allow AOL Messenger in Squid

To allow AOL Instant Messenger traffic via https with Squid, change the following line in the Squid configuration file

1. vi /etc/squid/squid.conf

2. Change:
acl SSL_ports port 443 563

acl SSL_ports port 443 563 5190

3. Send the Squid process a SIGHUP or use the service command.
/sbin/service squid reload

Updating BIND default ROOT servers (named.ca)

Use the BIND dig utility to retrieve a list of root name servers.

dig @a.root-servers.net . ns > named.ca

Make sure to copy named.ca to the directory containing your DNS maps. Restart BIND for the changes to take effect.

The 7 Layers of OSI

Anatomy of the Linux kernel

The Linux┬« kernel is the core of a large and complex operating system, and while it’s huge, it is well organized in terms of subsystems and layers. In this article, you explore the general structure of the Linux kernel and get to know its major subsystems and core interfaces. Where possible, you get links to other IBM articles to help you dig deeper.


Set up a LDAP server and clients

Using LDAP in a local network, you can allow your users to login and authenticate from anywhere on your network.

This tutorial will be split in 2 parts. In the first part, I will explain how-to install, configure the LDAP server, add a few users and group, in the second part, we will set up Linux client to authenticate through LDAP if the user does not exist on the local filesystem. read more…