Secure automatic remote backup

Secure automatic remote backup is easy. Just consider “crond + script + rsync + ssh + ssh key”. I am sure you will be addicted.

Noise Floor

Some engineers in the mobile industry have no basic knowledge of noise floor. I repeat below:

Noise Power N = kTb

k = Boltzman Constant
T = Absolute Temperature (Kelvin)
b = Channel Bandwidth

For LTE system occupying 10 MHz bandwidth, the noise floor is - 104 dBm. 

My tests on IRC blocking in 6in4 tunnel

I was helping to test goIPv6 tunnel (6in4 tunnel) which will be officially launched on 11 July 2013.  There are two security precautions imposed by the tunnel provider, namely blocking of SMTP and IRC connections.  This is quite understandable as malware infected PCs can send out spam and communicate with botnet command control centre through IRC port 6667 to launch malicious attacks.  Wait, I did not have IRC daemon.  How could I test it. I recalled that I could make use of netcat (nc) as follows:

Server side (listening mode ) : #nc -6 2401:300:0:1::8080 -l 6667

Win 7 Client side (transmit mode): c:\nc6 2401:300:0:1::8080 6667 –n –v

In the client side, nc6 for Windows 7 should be used which supports IPv6.  If connection could be put through, key inputs from the client side will be echoed in the server side.

Hopefully, the blocking test was conducted successfully. 

DNSv6

Trust me, there is no such new technology or protocol named as DNSv6. All authoritative DNS servers, whether riding on IPv4 or IPv6 backbone, can support AAAA record and ip6.arpa for reverse lookup !