Freebsd bad routing

Greg Barniskis nalists at
Fri Jul 15 14:32:25 GMT 2005

Joseh Martins wrote:
> Hello,
> I have a Freebsd server and some bad routes are been showed to me.
> Well, I didnt configured any routing protocols ... 
> With the command "netstat -r" I got a lot of routes with "UGHD" flags.
> I just need the default route (gateway).
> With the command "netstat -rs" I got this message:
> "127 bad routing redirects
>  1091 dynamically created routes"
> I appreciate some help.
> Tks a lot..

UGHD would seem to indicate that your box has been told (by ICMP 
redirects) not to use your configured default gateway to reach a 
specific host, but to use a different gateway instead. It is not 
necessarily a bad thing.

My guess: either (a) there are two or more available gateways 
upstream from you and they are legitimately collaborating to inform 
you of the best (possibly only) routes to use to get to various 
destinations, or (b) you are getting bad ICMP redirects from 
somewhere, either accidental or intentional.

If you know that one or more of the indicated UGHD routes is just 
plain wrong, that would be bad (maybe a spoofing or DoS attack of 
some kind). If you are unsure whether the routes are valid or not, 
contact the route provider upstream from you for clarification of 
whether this is legitimate (and whether you have specified the 
correct default gateway in the first place).

Greg Barniskis, Computer Systems Integrator
South Central Library System (SCLS)
Library Interchange Network (LINK)
<gregb at>, (608) 266-6348

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