Connections between different resolver types. Our scanner (S) finds open forwarder (OF) and open recursive resolver (ORR). A forwarder forwards the query to one or multiple recursive resolver (RR). Recursive resolver (RR and ORR) query the authoritative name server (ANS). Dashed arrows mark optional connections, like querying multiple recursive resolver or sending a response to our scanner. An empty arrow head marks a query response.
dnsscan – DNS Open Recursive Resolver Scanner Scanning Tool
Download File: https://urlcod.com/2vJEyl
Via our scans, we discovered 10054077 open resolvers and 178508 recursive resolvers. Figure 2 gives an overview of the connections between scanner and resolvers. Open resolvers are open to the Internet and can be used by anyone. They can be recursive resolvers or simple forwarders, which forward the query to a recursive resolver. Recursive resolvers perform the recursive lookup procedure which we can detect at our ANS. We can count and distinguish the two types of resolvers based on the traffic captured at our ANS. If the encoded IP address of the scan target and the source IP address of the resolver querying our ANS are identical, then the resolver is an open recursive resolver, otherwise the encoded IP address belongs to an open forwarding resolver. We expect a much higher number of open resolvers than recursive resolver, because as Kührer et al. [24] found, most open resolvers are routers or other embedded devices. There is little reason for them to host a recursive resolver, because they require more resources.
Figure 3 shows how many resolvers support a given chain length. There are clear spikes for common values like nine, used by Unbound and Microsoft DNS, or 17 as used by Bind. Another spike is at length 21, yet we are not aware which software causes it. The quick drop-off at the beginning is caused by resolvers, which query the same domain from different IP addresses often in the same subnet. In these cases only one of the resolvers performs the full recursion, the others stop early leading to the drop. This could be caused by open resolvers querying multiple recursive resolvers in a short amount of time. Alternatively, it might result from an attempt to pre-fetch data for multiple resolvers as soon as one recursive resolver in the pool sees a new domain name.
We have presented a new DDoS attack against DNS authoritatives that leverages amplification on the application layer. DNS Unchained achieves an amplification of 8.51 using standard DNS protocol features, by chaining alias records (e.g., CNAME) and forcing resolvers to repeatedly query the same authoritative name server. We performed full Internet scans and found 10 054 077 open DNS resolvers and 178 508 recursive resolvers. We determined that 74.3% of those resolvers support uncachable DNS responses, creating a large pool of amplifiers that can be abused for chaining attacks.
Wishlists: BooksWhat you perceive used to be my homepage. But though the notion of ahomepage was novel a few years ago, today it seems more fitting torefer to it as a contribution to the worldwide information at.tri.tion \*-'trish-*n\ \-'trish-n*l, -'trish-*n-*l\ n [L attrition-, attritio, fr. attritus, pp. of atterere] [ME attricioun, fr. (assumed) ML attrition-, attritio, fr. L]to rub against, fr. ad- + terere to rub - more at THROW 1: sorrow for one's sins that arises from a motive other than that of the love of God 2: the act of rubbing together : FRICTION; also : the act of wearing or grinding down by friction 3: the act of weakening or exhausting by constant harassment or abuse - at.tri.tion.al aj Some research that I do and projects that I work on: dnsscan - a fast scanner for identifying open recursive dns resolvers
SpyBye - helps web masters determine if their web pages have been compromised and install malware.
Netlayout, a physics driven network topologyvisualization tool.Systrace, interactive policy generationfor system calls. Supports Linux, Mac OS X, NetBSD and OpenBSD.Policy Repository.
Honeyd, a virtual honeynet daemon withpersonality. [Honeyd Honeypot Development]Worm Defense With Honeyd
OpenSSH - popular open source SSH implementation.
Privilege Separated OpenSSH, preventing privilege escalation.
libio, asimple library that abstracts data transport into data sources and data sinks connected via multiple filters.
Stegdetect,an automated tool for detecting steganographic content inimages. This steganography detector is capable of detecting: jsteg,jphide, and outguess 0.13b. It includes stegbreak, a tool thatlaunches dictionary attacks against steganographic systems and xsteg,a graphical frontend to stegdetect.
Vomit, Voice Over Misconfigured Internet Telephones.
Crawl, A Small and Efficient HTTP crawler.
libevent, asimple library for callbacks on I/O events. It includes supportfor kqueue.
ScanSSH, a fast open proxy and SSH Version scanner.
OutGuess, a universal steganography program, allowing for deniability, best image fits and more. It's core is independant of the cover data format.
NetBSD, a portable UNIX-likeoperating system.
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