ndisc6

ndisc6 - ICMPv6 Neighbor Discovery tool

Beschreibung

NDisc6 ist ein Unix-Programm, das das ICMPv6 Neighbor Discovery im Userland implementiert (normalerweise wird es vom Kernel ausgeführt). Es wird zum Nachschlagen der Link-Layer-Adresse (Layer-2-Adresse, MAC im Falle von Ethernet) eines beliebigen IPv6-Knotens auf der Verbindungsebene.

Die IPv6-Adresse des Knotens muss angegeben werden, ebenso wie die Netzwerkschnittstelle, über die die Suche erfolgen soll.

Syntax

$ ndisc6 [-1mnqv] [-r attempts] [-s source_ip] [-w wait_ms] <IPv6 address> <iface>

Anwendung

Sicherheit

ndisc6 sollte als root gesetzt werden, um die Benutzung durch nicht privilegierte Benutzer zu ermöglichen. Er gibt seine Root-Rechte auf, bevor er versucht, Daten aus dem Netz zu senden oder zu empfangen Daten aus dem Netz zu senden oder zu empfangen, um die möglichen Auswirkungen einer Sicherheitslücke zu verringern.

Anhang

Siehe auch

• Ndisc6

Dokumentation

RFC

RFC	Titel
0000

Man-Pages

• ping6(8)
• rdisc6(8)
• ipv6(7)

Links

Projekt

1. http://www.remlab.net/ndisc6/

TMP

NDISC6(8) System Manager's Manual NDISC6(8)

OPTIONS

-1 or --single
Exit as soon as the first advertisement is received (default).

-h or --help
Display some help and exit.

-m or --multiple
Wait for possible duplicate advertisements and print all of them.

-n or --numeric
If the first parameter is not a valid IPv6 address, do not try to resolve it as a DNS hostname.

-q or --quiet
Only display link-layer address. Display nothing in case of failure. That is mostly useful when calling the program from a shell script.

-r attempts or --retry attempts
Send ICMPv6 Neighbor Discovery that many times until a reply is received, or abort. By default, ndisc6 will try 3 times before aborting
(MAX_MULTICAST_SOLICIT and MAX_UNICAST_SOLICIT from RFC2461).

-s source_ip or --source source_ip
Specify the IPv6 address to be used as the source for the neighbor solicitation packets.

-V or --version
Display program version and license and exit.

-v or --verbose
Display verbose information. That is the default.

-w wait_ms or --wait wait_ms
Wait wait_ms milliseconds for a response before retrying. By default, ndisc6 waits 1 second between each attempts (RETRANS_TIMER from RFC2461).

If ndisc6 does not receive any response after the specified number of attempts waiting for wait_ms milliseconds each time, it will exit with code 2. On error, it exits with code 1. Otherwise it exits with code 0. This makes it possible to use the exit code to see if a host is on-link or not.

DIAGNOSTICS

If you get no response while you know the remote host is up, it is most likely that it is not on-link, that is to say, you must cross one or more routers to reach it. By design, IPv6 nodes ignore ICMPv6 Neighbor Discovery packets received from nodes not on the same link (i.e. Ethernet segment), for the sake of security. Technically, that is done by ensuring that the Hop limit (TTL) is 255.

Note that you cannot use ndisc6 to lookup the local host's link-layer address.