jail - vnet bug - ping: UDP connect: No route to host

[Özkan KIRIK]

Hello,

There is something wrong about routing lookup on vnet-jails. Although my
jail doesn't have IPv6 address, it tries to use IPv6 by default and
get "ping: UDP connect: No route to host" error. But it works by forcing to
use IPv4.

The problem is reproducable. This is a fresh insallation of FreeBSD
13.0-RC5:

root at f13:~ # uname -a
FreeBSD f13 13.0-RC5 FreeBSD 13.0-RC5 #0 releng/13.0-n244727-f8a134d0ef1:
Fri Apr  2 04:29:19 UTC 2021
root at releng1.nyi.freebsd.org:/usr/obj/usr/src/amd64.amd64/sys/GENERIC
 amd64

root at f13:~ # jail -c name=client persist vnet vnet.interface=em1

root at f13:~ # jexec client dhclient em1
DHCPREQUEST on em1 to 255.255.255.255 port 67
DHCPACK from 172.16.33.254
bound to 172.16.33.135 -- renewal in 900 seconds.

root at f13:~ # jexec client ifconfig em1
em1: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=481009b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,VLAN_HWFILTER,NOMAP>
ether 00:0c:29:3b:2a:de
inet 172.16.33.135 netmask 0xffffff00 broadcast 172.16.33.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

root at f13:~ # jexec client host www.google.com
www.google.com has address 216.58.212.100
www.google.com has IPv6 address 2a00:1450:4006:80b::2004

root at f13:~ # jexec client ping www.google.com
ping: UDP connect: No route to host

root at f13:~ # jexec client ping -4 -c 2 www.google.com
PING www.google.com (216.58.212.100): 56 data bytes
64 bytes from 216.58.212.100: icmp_seq=0 ttl=128 time=85.487 ms
64 bytes from 216.58.212.100: icmp_seq=1 ttl=128 time=90.243 ms

--- www.google.com ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 85.487/87.865/90.243/2.378 ms
root at f13:~ #