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[Qemu-discuss] bridged ICMP with no replies for tap0 on linux host
From: |
Kate F |
Subject: |
[Qemu-discuss] bridged ICMP with no replies for tap0 on linux host |
Date: |
Sat, 4 Oct 2014 00:05:18 +0100 |
Hi,
I'm bridging to tap0 on a linux host, and i can see pings arrive from
my VM (with tshark -i tap), but I see no ICMP reply.
I suspect this to be a problem with the host. I was using Debian
wheezy, with qemu (1.1.2+dfsg-6a+deb7u3). My configuration worked
there.
I upgraded to Jessie (qemu 2.1.2, Debian 2.1+dfsg-5), and that's when
my configuration stopped working. I've also tried installing the qemu
package I was using before (1.1.2+dfsg-6a+deb7u3) and my problem
persists.
So I believe this is not qemu's fault.
My VM is FreeBSD 10.0, amd64. Started thus:
; nice qemu-system-x86_64 -nographic -enable-kvm -m 768 -smp 2 \
-hda freebsd.img -hdb swap.img -hdc home.img \
-netdev tap,id=tap0,ifname=tap0,script=no,downscript=no \
-device rtl8139,netdev=tap0
The host is also amd64. I gave tap0 an IP so that I can try to
diagnose this problem. Here's the traffic I see over tap0 on the host:
; ifconfig tap0
tap0 Link encap:Ethernet HWaddr aa:26:97:82:c6:f1
inet addr:100.64.0.57 Bcast:100.64.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:523 errors:0 dropped:0 overruns:0 frame:0
TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:50062 (48.8 KiB) TX bytes:1068 (1.0 KiB)
; tshark -i tap0
Capturing on 'tap0'
1 0.000000 RealtekU_12:34:57 -> Broadcast ARP 42 Who has
100.64.0.57? Tell 100.64.0.5
2 0.000033 Apple_31:63:da -> RealtekU_12:34:57 ARP 42
100.64.0.57 is at 34:15:9e:31:63:da
3 0.000351 100.64.0.5 -> 100.64.0.57 ICMP 98 Echo (ping)
request id=0x1304, seq=0/0, ttl=64
4 1.034739 100.64.0.5 -> 100.64.0.57 ICMP 98 Echo (ping)
request id=0x1304, seq=1/256, ttl=64
5 2.083052 100.64.0.5 -> 100.64.0.57 ICMP 98 Echo (ping)
request id=0x1304, seq=2/512, ttl=64
6 3.155970 100.64.0.5 -> 100.64.0.57 ICMP 98 Echo (ping)
request id=0x1304, seq=3/768, ttl=64
...
And on the VM:
# ifconfig re0
re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=8009b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LINKSTATE>
ether 52:54:00:12:34:56
inet 100.64.0.5 netmask 0xffffff00 broadcast 100.64.0.255
inet6 fe80::5054:ff:fe12:3456%re0 prefixlen 64 scopeid 0x1
nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
# ping 100.64.0.57
PING 100.64.0.57 (100.64.0.57): 56 data bytes
^C
--- 100.64.0.57 ping statistics ---
4 packets transmitted, 0 packets received, 100.0% packet loss
#
# arp -a
? (100.64.0.5) at 52:54:00:12:34:56 on re0 permanent [ethernet]
? (100.64.0.57) at 34:15:9e:31:63:da on re0 expires in 1065 seconds [ethernet]
#
The host has no firewall (as far as I'm aware!) and iptables accepts everything:
# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
#
And some sysctls on the host:
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
Now I'm at a loss for what to do next.
Why am I seeing no ICMP replies on the host?
Where can I look next in order to diagnose that?
Thanks,
--
Kate
- [Qemu-discuss] bridged ICMP with no replies for tap0 on linux host,
Kate F <=