Re: [Qemu-devel] user-mode networking not allowing internet traffic

[Blue Swirl]

On Wed, Jun 15, 2011 at 9:12 PM, Amitava Shee <address@hidden> wrote:
> My ubuntu 11.04 guest is not able to connect to the internet when launched
> as -net user. Any help is much appreciated.
>
> qemu command line
> ==============
> address@hidden:/var/vms$ qemu-system-x86_64 -m 512 -drive
> index=0,media=disk,if=virtio,file=ub2.qcow2,boot=on -vnc :0 -monitor stdio
> -net nic,model=virtio,vlan=1 -net user,vlan=1,hostname=ubuntu2
>
> ifconfig output in guest
> =================
> address@hidden:~$ ifconfig eth0
> eth0      Link encap:Ethernet  HWaddr 52:54:00:12:34:56
>           inet addr:10.0.2.15  Bcast:10.0.2.255  Mask:255.255.255.0
>           inet6 addr: fe80::5054:ff:fe12:3456/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:11 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:1984 (1.9 KB)  TX bytes:1748 (1.7 KB)
>
> address@hidden:~$ nslookup google
> Server:        10.0.2.3
> Address:    10.0.2.3#53
>
> Non-authoritative answer:
> Name:    google.com
> Address: 74.125.115.104
> Name:    google.com
> Address: 74.125.115.106
> Name:    google.com
> Address: 74.125.115.105
> Name:    google.com
> Address: 74.125.115.147
> Name:    google.com
> Address: 74.125.115.103
> Name:    google.com
> Address: 74.125.115.99

This and the IP address of the eth0 show that the connection is working.

> address@hidden:~$ traceroute google.com
> traceroute to google.com (74.125.115.99), 30 hops max, 60 byte packets
>  1  10.0.2.2 (10.0.2.2)  0.469 ms  0.457 ms  0.453 ms
>  2  * * *
>  3  * * *
>  4  * * *
>  5  * * *
>  6  * * *
>  7  * * *
>  8  * * *
>  9  * * *
> 10  * * *
> 11  * * *
> 12  * * *
> 13  * * *
> 14  * * *
> 15  * * *
> 16  * * *
> 17  * * *
> 18  * * *
> 19  * * *
> 20  * * *
> 21  * * *
> 22  * * *
> 23  * * *
> 24  * * *
> 25  * * *
> 26  * * *
> 27  * * *
> 28  * * *
> 29  * * *
> 30  * * *

User mode network (SLIRP) only supports plain TCP and UDP, traceroute
and ping (which need ICMP) do not work.