After doing a
route add <host> 127.0.0.1 -blackhole
on a FreeBSD 8.3 host I noticed that nc <host> 80 would instantly return with
ENETUNRACH, instead of timing out, while blackhole routing to a real host would
time out. Checking in CURRENT (october 2012) reveals the same behaviour:
# netstat -nr
Routing tables
Internet:
Destination Gateway Flags Refs Use Netif Expire
default 10.0.2.2 UGS 0 1 vtnet0
10.0.2.0/24 link#1 U 0 1295 vtnet0
10.0.2.15 link#1 UHS 0 0 lo0
10.0.3.0/24 link#2 U 0 0 vtnet1
10.0.3.4 link#2 UHS 0 0 lo0
127.0.0.1 link#3 UH 0 1479 lo0
Internet6:
Destination Gateway Flags
Netif Expire
::/96 ::1 UGRS
lo0
::1 link#3 UH
lo0
::ffff:0.0.0.0/96 ::1 UGRS
lo0
fe80::/10 ::1 UGRS
lo0
fe80::%vtnet1/64 link#2 U
vtnet1
fe80::a00:27ff:fea4:1a9a%vtnet1 link#2 UHS
lo0
fe80::%lo0/64 link#3 U
lo0
fe80::1%lo0 link#3 UHS
lo0
ff01::%vtnet1/32 fe80::a00:27ff:fea4:1a9a%vtnet1 U
vtnet1
ff01::%lo0/32 ::1 U
lo0
ff02::/16 ::1 UGRS
lo0
ff02::%vtnet1/32 fe80::a00:27ff:fea4:1a9a%vtnet1 U
vtnet1
ff02::%lo0/32 ::1 U
lo0
# route add 4.2.2.1 127.0.0.1 -blackhole
add host 4.2.2.1: gateway 127.0.0.1
# route add 4.2.2.2 10.0.2.15 -blackhole
add host 4.2.2.2: gateway 10.0.2.15
# time nc -v -w 3 4.2.2.2 80
nc: connect to 4.2.2.2 port 80 (tcp) failed: Operation timed out
real 0m3.089s
user 0m0.000s
sys 0m0.014s
# time nc -v -w 3 4.2.2.1 80
nc: connect to 4.2.2.1 port 80 (tcp) failed: Network is unreachable
real 0m0.014s
user 0m0.000s
sys 0m0.014s
# uname -a
FreeBSD citske.localdomain 10.0-CURRENT FreeBSD 10.0-CURRENT #3 r241988M: Wed
Oct 24 15:21:27 CEST 2012
root@citske.localdomain:/usr/obj/usr/src/sys/CITSKE i386
A quick grep -r through the kernel did not provide me with any obvious mistake,
but a colleague suggested that for localhost an if 'statement' like the
following might be missing somewhere:
if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
m_freem(m);
return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
}
Any pointers would be appreciated
Nick Hibma
n...@van-laarhoven.org
GTD: Time management for chaotic people.
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
