Information, OpenSourceSoftware, passivedns, Security

PassiveDNS 0.5.0

I have pushed PassiveDNS version 0.5.0.

According to the roadmap, I have been at 0.5.0 for a while, and even started to implement stuff for the 1.5.0 version. But my real aim is the 1.0.0 release, and I have started all the activities for the 1.0.0 release, but I lack the statistics that I set in the roadmap when PassiveDNS ends. I have played it against pcaps with DNS attacks, Im fuzzing pcaps being read by PassiveDNS etc. so a 1.0.0 is hopefully not that far away 🙂

Some of the changes since my last blog post (v0.2.9):

* Logging of NXDOMAINs (-Xx -L nxdomain.log)
* DNS over UDP/TCP on IPv4 and IPv6 (Used to be just IPv4+UDP)
* Logging to stdout (-L – / -l -), both for NXDOMAINS and other DNS records.
* Implemented some hardening, including checking that client TID match server TID etc.
* Other small optimization and fixing a small memleak etc.

The way I implemented NXDOMAINS in PassiveDNS for now, makes it compete with the memory pool from “normal” domains/records. So if you have a fastflux or someone just querying for generated b0gus domains on your network, you might push out valid domains from the cache in favor for a NXDOMAIN. The reason I did this, is that it was faster than implementing an own memory pool for the NXDOMAINS and it give the possibility to log NXDOMAINS in current version with out to much hassle. If this way of implementing NXDOMAINS turns out to fight for memory more aggressively than one would like, one can always start two instances of PassiveDNS, one just looking for NXDOMAINS, and the other one looking for the regular domains. As I gain more experience with NXDOMAINS in PassiveDNS and get more feedback, Ill reconsider the implementation if needed 🙂

One note, the current logfile format will be stable until the 1.5.0 release (that is my intention at least), After that, my plan is to implement a customizable log format, and also more fields of interest will be available. If you have any additional data that you want to output and thoughts about how the output for those data should be, don’t hesitate to let me know 🙂

I ran into a security related bug on my Ubuntu 10.04 which might be triggered running PassiveDNS. I have emailed the Debian package maintainer and reported the bug to and also filed a bug report. The bug is fixed upstream in ldns long time ago, so hopefully it will be fixed soon in Ubuntu 10.04 too 🙂

For reporting issues or making feature request, please do so here.

Happy DNS Archiving 🙂


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