[Qemu-devel] about DHCP server in qemu

[Qemu-devel] about DHCP server in qemu

[octane indice]

Hello

I have some problems using the built-in DHCP server in qemu.

1. Is it possible to have guets connected?
If I launch 3 qemu, that I can do:
ping 10.2.0.15
ping 10.2.0.14
and so on. 
In order to simulate a network?

2. I have some problems with some distro to get an adress:
for example, a slackware get an IP
a tomsrtbt doesn't get an IP
it seems that netBSD doesn't get an IP too (but I have to check 
another time for that).

Thank you

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Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Thu, Sep 29, 2005 at 05:00:42PM +0200, octane indice wrote:
> Hello
> 
> I have some problems using the built-in DHCP server in qemu.
> 
> 1. Is it possible to have guets connected?
> If I launch 3 qemu, that I can do:
> ping 10.2.0.15
> ping 10.2.0.14
> and so on. 
> In order to simulate a network?
> 

No. In fact, the server is set up to always return the same IP in response to
a request. Even if it worked like a full fledged DHCP server, there's no way to
connect multiple guests together. The best you can do is slirpvde.

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[Brad Campbell]

Jim C. Brown wrote:
> On Thu, Sep 29, 2005 at 05:00:42PM +0200, octane indice wrote:
>> Hello
>>
>> I have some problems using the built-in DHCP server in qemu.
>>
>> 1. Is it possible to have guets connected?
>> If I launch 3 qemu, that I can do:
>> ping 10.2.0.15
>> ping 10.2.0.14
>> and so on. 
>> In order to simulate a network?
>>
> 
> No. In fact, the server is set up to always return the same IP in response to
> a request. Even if it worked like a full fledged DHCP server, there's no way to
> connect multiple guests together. The best you can do is slirpvde.
> 
err.. it works for me...
This gives me 9 qemu sessions that all get different 10.x.x.x ip addresses via dhcp

#!/bin/sh
rm /tmp/qemu-irc-*
for i in 1 2 3 4 5 6 7 8 9 ; do
qemu-img create -b /tracks/lin.img -f qcow /tmp/qemu-irc-$i
qemu -fda /tracks/floppy.img -hda /tmp/qemu-irc-$i -boot a -user-net -macaddr C0:0F:FE:01:01:9$i -m32 &
done

Regards,
Brad
-- 
"Human beings, who are almost unique in having the ability
to learn from the experience of others, are also remarkable
for their apparent disinclination to do so." -- Douglas Adams

Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Fri, Sep 30, 2005 at 01:50:47AM +0400, Brad Campbell wrote:
> >No. In fact, the server is set up to always return the same IP in response 
> >to
> >a request.
> err.. it works for me...

Yes, it seems that Fabrice has slipped in a few changes since I last looked at
the slirp code. :) The internal DHCP server can now support 16 dhcp clients.
That's for multiple clients within a single qemu guest though (think multiple
NICs here). I don't see any way for qemu guests to be able to ping each other
(for example) if they are both using user-net.

> Even if it worked like a full fledged DHCP server, there's no 
> >way to
> >connect multiple guests together. The best you can do is slirpvde.
> >
> This gives me 9 qemu sessions that all get different 10.x.x.x ip addresses 
> via dhcp
> 
> #!/bin/sh
> rm /tmp/qemu-irc-*
> for i in 1 2 3 4 5 6 7 8 9 ; do
> qemu-img create -b /tracks/lin.img -f qcow /tmp/qemu-irc-$i
> qemu -fda /tracks/floppy.img -hda /tmp/qemu-irc-$i -boot a -user-net 
> -macaddr C0:0F:FE:01:01:9$i -m32 &
> done
> 
> Regards,
> Brad

I find it suprising that this works. From the code in slirp/bootp.c it looks
like qemu's dhcp server will give out 10.0.2.15 first, then 10.0.2.16, and so
on (so it goes in sequential order). But thats within a single qemu session.
Theres no way for multiple user-net qemu guests to communicate (at least on
the ethernet level) so the guests should have the same ip address. Very strange.

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[octane indice]

En réponse à "Jim C. Brown" <jma5@umd.edu> :
> ------------------ Début du message d'origine --------------------
> 
> On Fri, Sep 30, 2005 at 01:50:47AM +0400, Brad Campbell wrote:
> > >No. In fact, the server is set up to always return the same
> > >IP in response to a request.
> > err.. it works for me...
> 
> Yes, it seems that Fabrice has slipped in a few changes since
> I last looked at the slirp code. :)

I use the last windows version of qemu. it's 0.7.2

> The internal DHCP server can now support 16
> dhcp clients.
> That's for multiple clients within a single qemu guest though
> (think multiple
> NICs here). I don't see any way for qemu guests to be able to
> ping each other
> (for example) if they are both using user-net.
> 
it would be good to get that working :)

> > Even if it worked like a full fledged DHCP server, there's no 
> > >way to connect multiple guests together. The best you
> > > can do is slirpvde.
> > >
> > This gives me 9 qemu sessions that all get different
> > 10.x.x.x ip addresses 
> > via dhcp
> > qemu -fda /tracks/floppy.img -hda /tmp/qemu-irc-$i -boot a
> > -user-net 
> > -macaddr C0:0F:FE:01:01:9$i -m32 &

Still doesn't work for me :/ I think that the problems comes
from the tomsrtbt.

if tomsrtbt is the only guest : no IP given
if tomsrtbt is launch with -macaddr xx : no IP given
if tomsrtbt is launch after another guest : no IP given

if I launch a real tomsrtbt, on a real host with a real DHCP
server on the network, tomsrtbt got an IP

-- 


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Re: [Qemu-devel] about DHCP server in qemu

[Oliver Gerlich]

octane indice wrote:
[...]
> 
> 
> Still doesn't work for me :/ I think that the problems comes
> from the tomsrtbt.
> 
> if tomsrtbt is the only guest : no IP given
> if tomsrtbt is launch with -macaddr xx : no IP given
> if tomsrtbt is launch after another guest : no IP given
> 
> if I launch a real tomsrtbt, on a real host with a real DHCP
> server on the network, tomsrtbt got an IP
> 

What dhcp client does tomsrtbt use?

If it uses dhclient (the ISC dhcp client), you should see some lines 
about DHCP in the syslog. With other clients (eg. pump) you can try to 
start the client manually (perhaps with some -v option to turn on 
verbose output) and see if it tells you something interesting.

Usually the clients indicate whether they found a dhcp server at all, 
and whether it supplied an ip address.


Good luck,
Oliver Gerlich

Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Fri, Sep 30, 2005 at 10:17:04AM +0200, octane indice wrote:
> > I don't see any way for qemu guests to be able to
> > ping each other
> > (for example) if they are both using user-net.
> > 
> it would be good to get that working :)
> 

Alas, that is so difficult it is nearly impossible.

> if tomsrtbt is the only guest : no IP given
> if tomsrtbt is launch with -macaddr xx : no IP given
> if tomsrtbt is launch after another guest : no IP given
> 
> if I launch a real tomsrtbt, on a real host with a real DHCP
> server on the network, tomsrtbt got an IP
> 

Strange. Sounds like a bug in either tomsrtbt or qemu. Do you have a floppy
image that can be downloaded?

> -- 
> 
> 
> ---------------------------------------------
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> 
> 
> _______________________________________________
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> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
> 

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[octane indice]

En réponse à "Jim C. Brown" <jma5@umd.edu> :
> > if tomsrtbt is the only guest : no IP given
> > if tomsrtbt is launch with -macaddr xx : no IP given
> > if tomsrtbt is launch after another guest : no IP given
> > 
> > if I launch a real tomsrtbt, on a real host with a real DHCP
> > server on the network, tomsrtbt got an IP
> 
> Strange. Sounds like a bug in either tomsrtbt or qemu. Do you
> have a floppy
> image that can be downloaded?
> 
http://www.toms.net/rb  or
http://public.planetmirror.com/pub/tomsrtbt/
http://downloads.planetmirror.com/pub/tomsrtbt/tomsrtbt-2.0.103.tar.gz

unzip it, and the file tomrtbt.raw is
directly bootable. The file is 1.7Mb big, but it's a floppy.
qemu -m 8 -fda tomsrtbt.raw -boot a
is enough.

The dhcpcd client is a self written client in lua.
I found that info:
http://not.toms.net/twiki/bin/view/Tomsrtbt/DHCPRequestsTooSmall
that says that the DHCP requests from tomsrtbt is very small (under
300 bytes) and the solaris DHCP server doesn't give IP. 
But linux DHCP server (and windows DHCP server) works fine.


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Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

Well I tried it myself and it doesn't work. eth0 gets an IP of 1.1.1.1 but
nothing is pingable.

I tried to make the packet sizes larger than 300 bytes just in case that was
the cause of the error (tho thats unlikely imvho), but that just got me a
syntax error from lua.

On Fri, Sep 30, 2005 at 04:51:41PM +0200, octane indice wrote:
> En r?ponse ? "Jim C. Brown" <jma5@umd.edu> :
> > > if tomsrtbt is the only guest : no IP given
> > > if tomsrtbt is launch with -macaddr xx : no IP given
> > > if tomsrtbt is launch after another guest : no IP given
> > > 
> > > if I launch a real tomsrtbt, on a real host with a real DHCP
> > > server on the network, tomsrtbt got an IP
> > 
> > Strange. Sounds like a bug in either tomsrtbt or qemu. Do you
> > have a floppy
> > image that can be downloaded?
> > 
> http://www.toms.net/rb  or
> http://public.planetmirror.com/pub/tomsrtbt/
> http://downloads.planetmirror.com/pub/tomsrtbt/tomsrtbt-2.0.103.tar.gz
> 
> unzip it, and the file tomrtbt.raw is
> directly bootable. The file is 1.7Mb big, but it's a floppy.
> qemu -m 8 -fda tomsrtbt.raw -boot a
> is enough.
> 
> The dhcpcd client is a self written client in lua.
> I found that info:
> http://not.toms.net/twiki/bin/view/Tomsrtbt/DHCPRequestsTooSmall
> that says that the DHCP requests from tomsrtbt is very small (under
> 300 bytes) and the solaris DHCP server doesn't give IP. 
> But linux DHCP server (and windows DHCP server) works fine.
> 
> 
> ---------------------------------------------
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> 
> 
> _______________________________________________
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> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
> 

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[Henrik Nordstrom]

On Sat, 1 Oct 2005, Jim C. Brown wrote:

> Well I tried it myself and it doesn't work. eth0 gets an IP of 1.1.1.1 but
> nothing is pingable.

1.1.1.1 is not a QEMU given IP.

Try manually assigning the IP 10.0.2.15/24(255.255.255.0) to the quest 
with a default route to 10.0.2.2. This should work.

It is quite possible the guest is not happy about something in the qemu 
DHCP reply. QEMU responds with a DHCP reply even if the client sent a 
BOOTP request and this can confuse some badly implemented BOOTP clients, 
and the number of DHCP options returned differ slightly from most DHCP 
servers possibly confusing some DHCP clients expecting additional options.

Regards
Henrik

Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Sun, Oct 02, 2005 at 04:39:59AM +0200, Henrik Nordstrom wrote:
> 1.1.1.1 is not a QEMU given IP.
> 

I know. I have no idea why that shows up.

> Try manually assigning the IP 10.0.2.15/24(255.255.255.0) to the quest 
> with a default route to 10.0.2.2. This should work.
> 

Already did. It does. 10.0.2.2 is pingable, at least.

> It is quite possible the guest is not happy about something in the qemu 
> DHCP reply. QEMU responds with a DHCP reply even if the client sent a 
> BOOTP request and this can confuse some badly implemented BOOTP clients, 
> and the number of DHCP options returned differ slightly from most DHCP 
> servers possibly confusing some DHCP clients expecting additional options.
> 

The client is definitely using (and expecting) DHCP, not BOOTP. Oddly enough,
it gets a timeout error. Very strange.

I tried to test out pump under tomsbrt but it refused to work; I'm too lazy to
attempt recompile a real dhcp client under a floppy linux. Since the pump binary
that I was using works under the redhat distro that it came from, I'm guessing
that its a bug in the LUA client. Will investigate further.

> Regards
> Henrik
> 
> 
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
> 

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[octane indice]

"Jim C. Brown" <jma5@umd.edu> :

> > 1.1.1.1 is not a QEMU given IP.
> 
> I know. I have no idea why that shows up.
>
tomsrtbt workaround if there is no DHCP server
 
-- 


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Re: [Qemu-devel] about DHCP server in qemu

[John R. Hogerhuis]

On Fri, 2005-09-30 at 09:10 -0400, Jim C. Brown wrote:
> On Fri, Sep 30, 2005 at 10:17:04AM +0200, octane indice wrote:
> > > I don't see any way for qemu guests to be able to
> > > ping each other
> > > (for example) if they are both using user-net.
> > > 
> > it would be good to get that working :)
> > 
> 
> Alas, that is so difficult it is nearly impossible.
> 

Nearly? Oh come on... you know it ain't possible, period.

Ping (ICMP) operates at the IP level. An unprivileged socket, which is
what user-net (slirp) uses can only send/receive packets at the ported
protocols level, which means UDP or TCP.

Of course, why ping? If all you need to do is validate connectivity,
find some ported protocol service to connect to in order to validate
connectivity.

If non-ported protocols like ICMP must be supported use tun/tap.

-- John.

Re: [Qemu-devel] about DHCP server in qemu

[Henrik Nordstrom]

On Fri, 30 Sep 2005, John R. Hogerhuis wrote:

> Nearly? Oh come on... you know it ain't possible, period.

It's possible. It just entails adding something like vde to user-net 
allowing multiple qemus to talk to each other (not using the slirp code).

but it's simpler and more robust to just use vde. There even exists a 
slirp plug for vde to allow user-net like connectivity out from the 
virtual lan provided by vde, and DHCP servers to make life simple.

Regards
Henrik

Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Fri, Sep 30, 2005 at 11:28:53AM -0700, John R. Hogerhuis wrote:
> Nearly? Oh come on... you know it ain't possible, period.
> 

What are you refering to? The ability of a single qemu to ping thru slirp,
or the ability of multiple qemus to ping each other using their guest ips?

The former can be done, as explained below, but it is probably more trouble
than its worth. The latter can not be done at all *IF* the guests have to
communicate thru the slirp layer. However, if the slirp layer is just used to
talk to the host and the LAN/internet and you have something else that deals
with guest-to-guest, then this can be done. slirpvde comes to mind here.

> Ping (ICMP) operates at the IP level. An unprivileged socket, which is
> what user-net (slirp) uses can only send/receive packets at the ported
> protocols level, which means UDP or TCP.
> 

Actually, it is really easy to add ping support to qemu using sockets. The only
issue here is privilege. (You need to be root in order to be able to use an
ICMP socket.)

An alternative would be to use "/sbin/ping -c 1" and parse its output in order
to simulate an actual ICMP connection. This is considerably harder, but definitely
possible.

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[octane indice]

En réponse à "Jim C. Brown" <jma5@umd.edu> :
> > Nearly? Oh come on... you know it ain't possible, period.
> 
> What are you refering to? The ability of a single qemu to ping
> thru slirp,
> or the ability of multiple qemus to ping each other using
> their guest ips?
> 
> The former can be done, as explained below, but it is probably
> more trouble
> than its worth. The latter can not be done at all *IF* the
> guests have to
> communicate thru the slirp layer. However, if the slirp layer
> is just used to
> talk to the host and the LAN/internet and you have something
> else that deals
> with guest-to-guest, then this can be done. slirpvde comes to
> mind here.
> 
> > Ping (ICMP) operates at the IP level. An unprivileged
> > socket, which is
> > what user-net (slirp) uses can only send/receive packets at
> > the ported
> > protocols level, which means UDP or TCP.
> 
> Actually, it is really easy to add ping support to qemu using
> sockets. The only
> issue here is privilege. (You need to be root in order to be
> able to use an
> ICMP socket.)
> 
> An alternative would be to use "/sbin/ping -c 1" and parse its
> output in order
> to simulate an actual ICMP connection. This is considerably
> harder, but definitely possible.
>
And what about a full IP connection beetween hosts? In order to
simulate a real network to do nfs/smtp/http/smb and so on?

I was thinking of a sort of a net-server which handles the DHCP
process, the connection for going outside (masquerade+DNS+SMB)
and the connection beetween hosts.
-- 

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Re: [Qemu-devel] about DHCP server in qemu

[Henrik Nordstrom]

On Mon, 3 Oct 2005, octane indice wrote:

> And what about a full IP connection beetween hosts? In order to
> simulate a real network to do nfs/smtp/http/smb and so on?

This is done with a TUN/TAP device, or via a VDE switch using TUN/TAP to 
connect to the host.

Regards
Henrik

Re: [Qemu-devel] about DHCP server in qemu

[Christian MICHON]

I think you meant "guests" instead of "hosts".
I second that. I would still like to use qemu to
perform network simulations myself...

On 10/3/05, octane indice <octane@alinto.com> wrote:
> And what about a full IP connection beetween hosts? In order to
> simulate a real network to do nfs/smtp/http/smb and so on?
>
> I was thinking of a sort of a net-server which handles the DHCP
> process, the connection for going outside (masquerade+DNS+SMB)
> and the connection beetween hosts.
> --

Re: [Qemu-devel] about DHCP server in qemu

[Henrik Nordstrom]

On Mon, 3 Oct 2005, Christian MICHON wrote:

> I think you meant "guests" instead of "hosts".
> I second that. I would still like to use qemu to
> perform network simulations myself...

This is done very nicely by VDE.

Regards
Henrik

Re: [Qemu-devel] about DHCP server in qemu

[Christian MICHON]

do you happen to have vde for win32 ?
If yes, please point it to me, because I've googled for one with no
luck... :)

On 10/3/05, Henrik Nordstrom <hno@marasystems.com> wrote:
> On Mon, 3 Oct 2005, Christian MICHON wrote:
>
> > I think you meant "guests" instead of "hosts".
> > I second that. I would still like to use qemu to
> > perform network simulations myself...
>
> This is done very nicely by VDE.
>
> Regards
> Henrik
>


--
Christian

Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Tue, Oct 04, 2005 at 09:47:56AM +0200, Christian MICHON wrote:
> do you happen to have vde for win32 ?
> If yes, please point it to me, because I've googled for one with no
> luck... :)
> 

Porting VDE to windows is fairly easy.

The hard part is getting qemu to work with it. Unlike POSIX OSes, Windows
doesn't provide unix sockets (so no c:\tmp\vde.ctl). I am not sure if the
-tun-fd option even works on Windows hosts.

So to make it work, we'd either have to add new code to qemu to connect to
VDE on windows or port qemu to cygwin (for real).

> On 10/3/05, Henrik Nordstrom <hno@marasystems.com> wrote:
> > On Mon, 3 Oct 2005, Christian MICHON wrote:
> >
> > > I think you meant "guests" instead of "hosts".
> > > I second that. I would still like to use qemu to
> > > perform network simulations myself...
> >
> > This is done very nicely by VDE.
> >
> > Regards
> > Henrik
> >
> 
> 
> --
> Christian
> 
> 
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
> 

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[Henrik Nordstrom]

On Tue, 4 Oct 2005, Christian MICHON wrote:

> do you happen to have vde for win32 ?
> If yes, please point it to me, because I've googled for one with no
> luck... :)

Should build fine using cygwin I think.

Regards
Henrik

Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Mon, Oct 03, 2005 at 05:55:58PM +0200, octane indice wrote:
> And what about a full IP connection beetween hosts? In order to
> simulate a real network to do nfs/smtp/http/smb and so on?
> 
> I was thinking of a sort of a net-server which handles the DHCP
> process, the connection for going outside (masquerade+DNS+SMB)
> and the connection beetween hosts.

huh? hosts?

if u really mean guests, then i'd recommend using vde (or wait for Fabrice's new
group usernet mode). if u really mean host, i'd recommend using tuntap.

> -- 
> 
> ---------------------------------------------
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> 
> 
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> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
> 

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] about DHCP server in qemu

[octane indice]

En réponse à "Jim C. Brown" <jma5@umd.edu> :
> On Mon, Oct 03, 2005 at 05:55:58PM +0200, octane indice wrote:
> > And what about a full IP connection beetween hosts? In order
> > to simulate a real network to do nfs/smtp/http/smb and so on?
> > 
> > I was thinking of a sort of a net-server which handles the
> > DHCP process, the connection for going outside
> > (masquerade+DNS+SMB)
> > and the connection beetween hosts.
> 
> huh? hosts?
> 
er, no. It shoulded be guests.

> if u really mean guests, then i'd recommend using vde (or wait
> for Fabrice's new group usernet mode).

Ok, I'm waiting for that.

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