Thank you for your responses sirs and the advice. My target is to, 1. Intercept SYN packet 2. Obtain the destination IP address 3. Resolve the TLD of that IP 4. then bind each packet to queues depending on the TLD I will check on nslookup, open DNS client utilities and dns_resolver libraries as you experts suggested :) Best Regards, H. Hasitha Shan Date: Tue, 8 Jul 2014 15:20:16 +0200 Subject: Re: Re: Linux Kernel Module program to obtain domain name from IP From: kristofer.hallin@gmail.com To: kristof@sigsegv.be CC: kernelnewbies@kernelnewbies.org; shhuiw@163.com; sudipm.mukherjee@gmail.com; hh_shan@live.com There's a research project called Name Based Sockets where this have been done. Take a look at: https://www.sics.se/projects/name-based-sockets If you search for name based sockets on Google you will find a kernel module and user space code doing this. On 8 Jul 2014 15:07, "Kristof Provost" <kristof@sigsegv.be> wrote: On 2014-07-08 20:19:09 (+0800), shhuiw <shhuiw@163.com> wrote:
DNS loopkup should use UDP packet, and you have to construct UDP request
based on your captured IP addresses in your module.
DNS can actually use both TCP and UDP.
And you have to use DNS server fallback lists and time-out control if some DNS
server cannot work well.
Yeah. Doing DNS lookups (forward or reverse) is complicated. There's a dns_query function in the kernel (net/dns_resolver), which apparently upcalls into user space, but I'd avoid dealing with DNS in the kernel at all. Just pass the IP address to user space and let it deal with it. There are plenty of DNS libraries available. Odds are you need to pass the resulting information to user space anyway, so you're not really losing anything. What are you trying to accomplish anyway? Regards, Kristof _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies