Introduction
I have a little home Network behind my Wireless Access Point. But, lately one of the boxes that I need to access has been up and down. And, I really need it to be up.
Quick Analysis
I am a bit disinclined to do heavy network troubleshooting. I just need things up; reliably and running.
What is wrong?
- Is it a Comcast problem; btw Comcast is my ISP
- Is it just this old LinkSys Home Router – I have it fronting the internal network; acting as a DHCP host, distributing IPs, and forwarding network packets based on Port Forwarding – Traffic Cop, the good one – Looks at Port# and sends it over to specific machines
- Is it my Linux box (CentOS)
- Is it an on \ off again Software Firewall on the Linux box
Usually, it wouldn’t bother me. But, I really need to learn.
Comcast Network (thinking….)
I know I am entitled to 5 IPs from Comcast, and I have a spare one.
So for this one host that I need to communicate with, I will like to bypass the LinkSys Router and connect directly to the network switch that is connected to the Cable Modem
Comcast Network (Connected)
Once that connection is made, I have a good world reachable IP Address. Hopefully, it will stay up and available.
Fully Qualified Domain Name
As the host is a box that will be running Hadoop, I know I need really good and firm FQDN.
What is the Network Domain Info
What is Comcast DHCP giving out?
Checked /etc/resolv.conf and have these entries:
|
What do we want it to be?
I really do not care much about the details. But, I need to be able to control my destiny; which means having my own domain data:
Here is what we came up with:
|
DNS Server Changes
Create A and “Reverse Lookup” entries for our Linux host.
Our DNS Server happens to be Windows-based, and we will just use a GUI to make the changes.
Linux Node DNS Changes
On the Linux node, update /etc/resolv.conf with our updated DNS entries.
# Generated by NetworkManager
domain labDomain.org
search labDomain.org
nameserver 24.6.75.90
Explanation:
- Our domain name is labDomain.org
- Our DNS Suffix is labDomain.org
- In our case, as we are getting an IP from Comcast and a homegrown network domain, we need to ensure that we choose our own DNS Server (that is also reachable over the Net).
Work Arounds
In case you do not have a good DNS Server or limited network addresses, please consider using a third party Dynamic DNS Provider.
My favorite used to be http://dyn.com/dns/, but it seems that they are pulling back on free FQDNs.
Though I have yet to try noip.com, I have been hearing good things about it.
Learning in the Open 