IPv6 SpecialTests

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IPv6 Special Tests

IPscan includes the following tests to identify known weak protocols or poorly configured services, which may be exploited.


It is important to note that the same exploits may well apply to IPv4 hosts running the same protocols.

Links to other material

  • IPv6 - an overview of IPscan (IPv6 Port Scanner)
  • IPv6_Firewalls - some observations on IPv6 firewalls and address selections
  • IPv6_Ports - a list of the default TCP/IP and UDP/IP ports which IPscan will test
  • ScanStatus - a description of the reportable states for each tested TCP/IP or UDP/IP port
  • ScanAutomation - a quick overview of IPv6 TCP/UDP port scan automation using wget
  • IPv6_DEBUG - some steps for debugging IPv6 access to my IPv6 Port Scanner
  • IPv6_Windows7 - some useful Win7 IPv6-related commands
  • Raspberry_Pi_IPv6_firewall_tester - a quick HowTo describing the steps to make your own RasPi-powered IPv6 firewall tester.


NTP Monitor List Query UDP/123[1]

The NTP protocol daemon, in versions prior to 4.2.7, supported a feature which reported a list of up to 600 clients which had used the queried NTP server as their time reference.

If an attacker uses a spoofed source address then a victim can be flooded with considerable NTP traffic. The size of the response is typically considerably larger than the request and consequently the attacker is able to amplify the volume of traffic directed at the victim. Additionally, because the responses are legitimate data coming from valid servers, it is especially difficult to block these types of attacks. The solution is to disable “monlist” within the NTP server or to upgrade to the latest version of NTP (4.2.7) which disables the “monlist” functionality.

To prevent your NTP daemon being used in DDoS attacks it is necessary to disable “monlist” functionality. On a public-facing NTP server that cannot be updated to version 4.2.7 or later, add the “noquery” directive to the “restrict default” line in the system’s ntpd.conf, as shown below:

restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

See CVE-2013-5211 for further details.

SNMP Queries UDP/161

IPscan performs three SNMP queries. SNMP supports a variety of versions and authentication methods and since IPscan cannot know the credentials to use to test your system it defaults to using commonly-used, and therefore insecure, community strings.

Port/Special CaseSNMP versionTest performed, credentials used
UDP/161v1GET with 'public' community string
UDP/161[1]v2cGET with 'private' community string
UDP/161[2]v3EngineID Discovery, credentials not required

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