Can't traceroute to my box

[Uwe Doering]

Frank DeChellis wrote:
> Hi.
> 
> I am new to FreeBSD.  I have been using NetBSD for about 9 years.  I have
> FreeBSD v. 4.8 Release #1 running.  Everything is smooth expect for one
> thing.
> 
> I can't traceroute to the box.  I can do a traceroute -I to it, but not a
> regular traceroute, which tells me something about UDP, but I don't know
> where to look.
> 
> IS there a file somewhere that is closing certain UDP ports that respond to
> traceroute?

Apart from the usual suspect (firewall filtering out the incoming UDP 
and/or outgoing ICMP packets), what does

   sysctl net.inet.udp.blackhole

show?  If it is _not_ 0 it means that UDP ports that are not in use 
don't generate a response, which implies that the normal 'traceroute' 
won't work.  This feature is intended to make the life of (port 
scanning) hackers even more miserable than it must be already.  There is 
a related variable for TCP as well (net.inet.tcp.blackhole).

    Uwe
-- 
Uwe Doering         |  EscapeBox - Managed On-Demand UNIX Servers
gemini at geminix.org  |  http://www.escapebox.net