Null route

Null route

In computer networking, a null route (blackhole route) is a network route (routing table entry) that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering. The rest of this article deals with null routing in the Internet Protocol (IP).

Null routes are typically configured with a special route flag, but can also be implemented by forwarding packets to an illegal IP address such as 0.0.0.0, or the loopback address.

Null routing has an advantage over classical firewalls since it is available on every potential network router (including all modern operating systems), and adds virtually no performance impact. Due to the nature of high-bandwidth routers, null routing can often sustain higher throughput than conventional firewalls. For this reason, null routes are often used on high-performance core routers to mitigate large-scale denial-of-service attacks before the packets reach a bottleneck, thus avoiding collateral damage from DDoS attacks — although the target of the attack will be inaccessible to anyone. Blackhole filtering can also be abused by malicious attackers on compromised routers to filter out traffic destined to a certain address.

However, routing typically only works on the Internet Protocol layer and is very limited in packet classification. It is bound to be stateless due to the nature of IP routers. Typically, classification is limited to the destination IP address prefix, source IP address and incoming network interface.

Specific examples

Nullrouting with iproute2 on Linux:

$ ip route add blackhole 192.168.32.128/32[1]

Nullrouting with 'route' on Solaris and BSD:

$ route add -host 10.10.0.1 127.0.0.1 -blackhole 
$ route add -net 10.10.64.0/18 127.0.0.1 -blackhole

Creating a discard route on Juniper Networks' Junos:

set routing-options static route 192.168.0.0/16 discard

Routing to the Null0 interface on Cisco IOS:

ip route 192.168.0.0 255.255.0.0 Null0[2]

Windows XP/Vista does not support reject or blackhole arguments via route, thus an unused IP address (e.g. 192.168.32.254) must be used as the target gateway:

route -p ADD 192.168.32.128 MASK 255.255.255.255 192.168.32.254

See also

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Pennsylvania Route 145 — PA Route 145 Route information Maintained by Pe …   Wikipedia

  • Pennsylvania Route 474 — PA Route 474 Route information Maintained by PennDOT Length: 3.20 mi[1 …   Wikipedia

  • Arizona State Route 51 — Karte …   Deutsch Wikipedia

  • La Route du patriarche — Roman sur les Royaumes oubliés La Route du Patriarche Titre Original Road of the Patriarch Auteur R.A. Salvatore 1ère parution en français 2006 Dernière édition Milady (2009) Traduction Laurence Richard Illustration Todd Lockwood …   Wikipédia en Français

  • BlockHosts — Infobox Software name = BlockHosts caption = BlockHosts developer = Avinash Chopde latest release version = 2.4 latest release date = June 17, 2008 operating system = FreeBSD,OpenBSD,NetBSD,DragonflyBSD,Linux genre = Intrusion prevention license …   Wikipedia

  • Bit bucket — The bit bucket is jargon for where lost computerized data has gone, by any means; any data which does not end up where it is supposed to, being lost in transmission, a computer crash, or the like is said to have gone to the bit bucket mdash; that …   Wikipedia

  • Woodbridge Township, New Jersey — Infobox Settlement official name = Woodbridge Township, New Jersey nickname = motto = imagesize = image caption = image mapsize = 250x200px map caption = Map of Woodbridge Township in Middlesex County. Inset: Location of Middlesex County… …   Wikipedia

  • Miami — This article is about the city in Florida. For other uses, see Miami (disambiguation). Miami   City   …   Wikipedia

  • Rochester, New York — This article is about the city of Rochester in Monroe County. For the town in Ulster County, see Rochester, Ulster County, New York. For the metropolitan area, see Rochester, New York metropolitan area. Rochester   City   …   Wikipedia

  • Cherry Hill Township, New Jersey — Infobox Settlement official name = Cherry Hill Township, New Jersey settlement type = Township nickname = motto = imagesize = image caption = image mapsize = 250x200px map caption = Location of Cherry Hill Township in Camden County. Inset;… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”