Bug 27852

    You have one interface xl0 with ip 100.1.1.10 and netmask 255.255.255.0
    and your gateway is 150.1.1.1. To add this gateway you should add a
    route to this host lets say: route add -net 150.1.1.0/24 -iface xl0;
     and then we should add the default : route add default 150.1.1.1.
    That's the right way but what the kernel say ? - "Network Unreachable" ?!?
    But we have route to that network , aren't we ?
    And here is one way this could be done :
        route add default 100.1.1.10
        route add -net 150.1.1.0/24 -iface xl0
        route change default 150.1.1.1
    Wow everithing works ! :)
    But do you think that's the right way to be done ?

Fix: I looked in the kernel source and found this in rtrequest :
        if ((ifa = ifa_ifwithroute(flags, dst, gateway)) == 0)
                            senderr(ENETUNREACH);
    ifa_ifwithroute() can't find a route that exest ?
    Then I look at ifa_ifwithroute() and saw this :
        if (ifa == 0) {
                    struct rtentry *rt = rtalloc1(dst, 0, 0UL);
    Why we search a route to a destination but not to a gateway ?
    I change it ofcourse and now everything works fine.
    And this is the changed line just one variable changed :
        if (ifa == 0) {
                    struct rtentry *rt = rtalloc1(gateway, 0, 0UL);

    And here is the patch (hum :)) for this :



A long long patch. If you have any sugestions I'd like to hear it
    as soon as posible because there are some other things in the kernel
    routing that I want to discuss.--Jg85XgsQOodlHmCX0cZpLcuN5eHyAtz48IKCeHufPGTnGlpo
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--- route.c.old Thu May 17 02:14:03 2001
+++ route.c     Sun Jun  3 11:18:07 2001
@@ -425,7 +425,7 @@
        if (ifa == 0)
                ifa = ifa_ifwithnet(gateway);
        if (ifa == 0) {
-               struct rtentry *rt = rtalloc1(dst, 0, 0UL);
+               struct rtentry *rt = rtalloc1(gateway, 0, 0UL);
                if (rt == 0)
                        return (0);
                rt->rt_refcnt--;
How-To-Repeat:         just try do add default gw from network that none of your
        interfaces is.