More fun with Signed / Unsigned Comparisons

Here is why one should be very careful while mixing signed and unsigned integer comparisons. Take a look at this code snippet below:

The President does not want to nuke North Korea, but lets see how the program actually interprets this. If you try compiling and executing this program in a 32-bit environment, it … [Read more…]

Using Lets Encrypt Certificates for Postfix and Dovecot

Recently, the self-signed certificates that I use for Postfix / Dovecot on my mailserver expired and I decided to try using Lets Encrypt to obtain certificates for them. Lets Encrypt is a fully trusted free Certificate Authority developed by a consortium of organizations to promote a more secure internet. I particularly like the fact that … [Read more…]

Using ddclient for DDNS

I use ddclient to update my dynamic IP address which is assigned by Comcast. This is the gist for the ddclient configuration:

Memory Barriers on x86

Recently, there have been some interesting discussions at work going on around the correctness of system critical code and how memory barriers actually operate on x86. This is a very poorly understood concept mainly due to the ambiguity of the Intel / AMD manuals on the subject. x86 has a much stronger memory model than … [Read more…]

Upgrading the HomeLab

I have been wanting to upgrade my homelab for a while now to allow for running more experimental VMs. I already had six VMs running on the HP Microserver which was much more than could be handled by the AMD Turion 1.2Ghz single core 2 threaded CPU. I decided to go with the ThinkServer TS140 … [Read more…]

India in 2016

India, here I come! Excited that I will be able to attend Amartithi this year and also meet Naniji in Delhi. Its not that I am going after a long time. In fact, on an average I have been taking atleast one trip a year since coming to the states in 2010. Its just that … [Read more…]

OpenWRT: Allowing PPTP clients to connect

If the worst outcome of trying to upgrade the router firmware is that you might brick it, surely the second worst is when your wife is unable to connect to her VPN when a work emergency demands it. Late on Monday night, Aish sat down to get some work done for a presentation she had the next day … [Read more…]

TP-Link Archer C7: How not to NAT

I have had the TP-Link Archer C7 wireless router for a few months now. Although the hardware in this router is great bang-for-buck, the stock firmware leaves much to be desired. I run a number of servers out of my homelab which requires the router to be configured with port based NAT rules. I found … [Read more…]