can't ping guest from host on bridged network interface

[sknaumov]

My host is Xubuntu 12.10 and guests are Oracle Linux 5.8 machines. My host has 2 interfaces - eth0 with access to internet and eth1 with address 172.16.0.10. Each guest machine has internal eth0 interface bridged with host eth0 (and, as the host, they are getting address by dhcp on eth0) and internal eth1 interface bridged with host eth1. Each guest (with address 172.16.0.x on eth1) can ping all other guest machines, but when I try to ping host from guest, only arp requests are sent to host to which it doesn't respond.

On guest:

[root@host1 oracle]# ping 172.16.0.10
PING 172.16.0.10 (172.16.0.10) 56(84) bytes of data.
From 172.16.0.1 icmp_seq=2 Destination Host Unreachable
From 172.16.0.1 icmp_seq=3 Destination Host Unreachable
...

On host:

root@sknaumov:/etc# tcpdump -i eth1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
10:59:25.321777 ARP, Request who-has sknaumov.localdomain tell host1.localdomain, length 28
10:59:26.322357 ARP, Request who-has sknaumov.localdomain tell host1.localdomain, length 28
...

When I'm trying to ping guest from host, tcpdump on guest shows nothing (although promiscuous mode is enabled for eth1 interface configuration in guest vm settings).

If I set up manual arp entries on host and guest, then echo request from guest is visible on host, but host doesn't respond to guest. There is no active iptables rules (iptables-save outputs nothing).

It is interesting, but I can ping guest from host and vice versa using addresses obtained through DHCP which they have on bridged eth0.

I had the same problem with Debian Squeeze host, Oracle Linux 5.8 guests and VirtualBox 4.2.4.

[sknaumov]

VirtualBox log file

[sknaumov]

VirtualBox log file (previous)

[Aleksey Ilyushin]

Most probably an Ethernet cable is not plugged into host's eth1. Even if the interface is assigned an IP address and is up the host won't try to send anything via physically unplugged interface. If this is a case, you should either plug the cable or use host-only attachment instead.

[sknaumov]

Replying to aleksey:

Most probably an Ethernet cable is not plugged into host's eth1.

Yes, it is the case. Thanks!