A common application for loose source-routing, used mainly by service
providers, is troubleshooting routing problems in the Internet. It can
be quite helpful to trace a route *from* a specified node, *to* a
Of course, this doesn't mean that you should allow loose source-routed
traffic into your internal network from external sources, however,
many service providers allow source-routed traffic transit on their
backbones for specifically this purpose.
At 12:01 PM 1/2/96 -0500, Ray Hooker wrote:
>I know certain things about source routing:
> - Stated purpose (see RFC 791) was to allow the specification of routing
> information to be used by gateways.
> - I know how to code source routed packets under UNIX (or Linux).
> - They can be used in attacking TCP/IP hosts (see IPEXT paper on
> weaknesses in the TCP/IP protocol.
> - Microsoft's tracert module purportedly has an option to use
> loose source-routing to debug network problems (this is their
> version of traceroute).
> - Some networks configure their routers to reject source-routed packets.
> - Firewalls should reject source-routed packets.
>What I am curious about is what functions or applications, if any, commonly
use source-routing. I haven't noticed any Telnet clients that, for example,
could specify a loose source-routing to contact a particular host. I have
searched the Comer series on Internetworking with TCP/IP and other
references, but see little information on actual usage.
>Ray Hooker, rayhook @
>Secure I/T Inc.
Paul Ferguson || ||
Consulting Engineering || ||
Reston, Virginia USA |||| ||||
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