Re: Why RNF_IGNORE?

[Henric Jungheim <henric@attbi.com>]

Just replying to myself w/ some little details...

Henric Jungheim wrote:

> I ran into a bit of a weird problem that I think it caused by this 
> flag. Try something like this (assuming fxp0 is the only 
> interface--or, at least, the one w/ the default route):
>
> GW = default route (on the fxp0 subnet)
> TEST = some box on the fxp0 subnet (other than GW) 


These addresses do need to be such that searching for "TEST" requires 
backtracking.

My routing table looked like this after getting the redirect:

Routing tables

Internet:
Destination        Gateway            Flags     Refs     Use    Mtu  
Interface
default            192.168.201.1      UGS         1        3   1500   fxp0
127.0.0.1          127.0.0.1          UH          1        6  33224   lo0
192.168.1/24       link#2             UC          0        0   1500   fxp1
192.168.201/24     link#1             UC          0        0   1500   fxp0
192.168.201.1      0:0:24:c0:d:be     UHL         1        0   1500   fxp0
192.168.201.3      192.168.201.3      UGHD        0        1   1500   fxp0

(In this case, GW = 192.168.201.1 and TEST=192.168.201.3.)

BTW, is it ever sane to send or accept a host ICMP redirect where the 
destination is on the same subnet as the gateway?  (The subnet mask is 
known in this case since it has to be the interface's mask.)

> route -n flush
> ifconfig fxp0 down
> route -n add default GW
> ifconfig fxp0 up
> ping TEST


To see some of what is going on, I massaged the output of "netstat -nrAf 
inet" and fed the result to graphviz-1.8.5's "dot" (it looks like the 
port is 1.7.something, but I'd already built 1.8.5 builds w/o too much 
fuss).  Something like this prints the tree:

    netstat -nrAf inet | awk -f graphnet | dot -Tps | lpr

Where "graphnet" is the following:

function quotename(name) {
    return "\"" name "\"";
}

BEGIN            {
                print "digraph netstat {";
                print "    size=\"8,10.5\";";
                print "    margin=\"0.25\";";
                print "    node [fontsize=8];";
                link="";
            }
$1 !~ /^0x/        { next; }
/\(root node\)/        { print "   ", quotename($1), 
"[label=Root,shape=box];" }
$2 ~ /\([0-9]+\)/    {
                name = substr($2, 2, length($2) - 2);
                if($6 == "mk")
                    name = name "/" substr($9, 3, length($9) - 4);
                print "   ", quotename($1), "[label=\"" name "\"];";
                print "   ", quotename($1), "-> {", quotename($3), 
quotename($5), "}" ";";
            }
$2 !~ /^[(]/        { print "   ", quotename($1), "[label=\"" $8, $4 
"\\n" $2 "\\n" $3 "\",shape=box];" }
            { if(link != "") { print "   ", link, "->", quotename($1), 
"[arrowhead=none];"; link = "" } }
/=>/            { link = quotename($1); }
END            { print "}" }