ssh session with qemu-arm using busybox

ssh session with qemu-arm using busybox

[Pintu Agarwal]

Hi,

I have a qemu-arm setup with busybox which I normally use to test my
kernel changes.
I use this command to boot it:

QEMU-ARM$
qemu-system-arm -M vexpress-a9 -m 1024M -kernel
../KERNEL/linux/arch/arm/boot/zImage -dtb
../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram rdinit=/sbin/init
ip=dhcp" -nographic -smp 4

This includes, my own custom kernel and rootfs build.
For rootfs I use busybox and create cpio image and use it as initrd.

But, every time, if I have to copy some files inside qemu, I need to
create create roofs image.
This is painful.

So, now I am exploring how to transfer files from my ubuntu pc to
qemu-session using "ssh".
I know this is possible, but I am still not successful, and bit lazy
to explore these.

I am sure, many of you people would have explored already "how to use
ssh over qemu" and found a easy method.
So, if anybody have easy setup please share with me.

I could see that after adding "ip=dhcp" I get the eth0 interface like this:
/ # ifconfig
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
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1180 (1.1 KiB)  TX bytes:1180 (1.1 KiB)
          Interrupt:22

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

But I could not ping it from ubuntu PC.


Regards,
Pintu

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Re: ssh session with qemu-arm using busybox

[Nick Kossifidis]

Στις 2019-03-11 16:34, Pintu Agarwal έγραψε:
> Hi,
> 
> I have a qemu-arm setup with busybox which I normally use to test my
> kernel changes.
> I use this command to boot it:
> 
> QEMU-ARM$
> qemu-system-arm -M vexpress-a9 -m 1024M -kernel
> ../KERNEL/linux/arch/arm/boot/zImage -dtb
> ../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
> rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram rdinit=/sbin/init
> ip=dhcp" -nographic -smp 4
> 
> This includes, my own custom kernel and rootfs build.
> For rootfs I use busybox and create cpio image and use it as initrd.
> 
> But, every time, if I have to copy some files inside qemu, I need to
> create create roofs image.
> This is painful.
> 
> So, now I am exploring how to transfer files from my ubuntu pc to
> qemu-session using "ssh".
> I know this is possible, but I am still not successful, and bit lazy
> to explore these.
> 
> I am sure, many of you people would have explored already "how to use
> ssh over qemu" and found a easy method.
> So, if anybody have easy setup please share with me.
> 
> I could see that after adding "ip=dhcp" I get the eth0 interface like 
> this:
> / # ifconfig
> 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
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:2 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:2 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:1180 (1.1 KiB)  TX bytes:1180 (1.1 KiB)
>           Interrupt:22
> 
> lo        Link encap:Local Loopback
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           UP LOOPBACK RUNNING  MTU:65536  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
> 
> But I could not ping it from ubuntu PC.
> 
> 
> Regards,
> Pintu
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

You may use the hostfw argument on qemu, e.g...

-netdev user,id=unet,hostfwd=tcp::2222-:22 \
-net user \

and you 'll get guest's port 22 to be forwarded to hosts port 2222, so 
you can do

ssh root@localhost:2222

from the host.

Regards,
Nick

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Re: [Qemu-devel] ssh session with qemu-arm using busybox

[BALATON Zoltan]

On Mon, 11 Mar 2019, Pintu Agarwal wrote:
> I am sure, many of you people would have explored already "how to use
> ssh over qemu" and found a easy method.
> So, if anybody have easy setup please share with me.
>
> I could see that after adding "ip=dhcp" I get the eth0 interface like this:
> / # ifconfig
> 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
>          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>          RX packets:2 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:2 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:1000
>          RX bytes:1180 (1.1 KiB)  TX bytes:1180 (1.1 KiB)
>          Interrupt:22
>
> lo        Link encap:Local Loopback
>          inet addr:127.0.0.1  Mask:255.0.0.0
>          UP LOOPBACK RUNNING  MTU:65536  Metric:1
>          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>          collisions:0 txqueuelen:1000
>          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
>
> But I could not ping it from ubuntu PC.

This should already be documented here:
https://wiki.qemu.org/Documentation/Networking

The default QEMU network is -net user slirp based networking that provides 
outbound connectivity from the virtual machine but no ping or inbound 
connections. I.e. you can ssh from your guest to your host (so you could 
use scp in your guest to copy files from your host) or use some other 
networking (such as tap) that allows the host to connect to guest (but 
then you'll need to arrange routing and dhcp if you want that on your 
host otherwise your guest will only see your host). Hope this helps.

Regards,
BALATON Zoltan

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Re: ssh session with qemu-arm using busybox

[Pintu Agarwal]

>
> -netdev user,id=unet,hostfwd=tcp::2222-:22 \
> -net user \
>
> and you 'll get guest's port 22 to be forwarded to hosts port 2222, so
> you can do
>
> ssh root@localhost:2222
>
> from the host.
>

I tried many different options, but unfortunately none worked for me.
1)
qemu-system-arm -M vexpress-a9 -m 1024M -kernel
../KERNEL/linux/arch/arm/boot/zImage -dtb
../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram rdinit=/sbin/init
ip=dhcp" -nographic -smp 4 -netdev user,id=unet,hostfwd=tcp::2222-:22
-net user

With this the eth0 interface is removed, and I see this message
(although login works):
qemu-system-arm: warning: hub 0 with no nics
qemu-system-arm: warning: netdev unet has no peer
Booting Linux on physical CPU 0x0
<skip>
NET: Registered protocol family 17
<skip>
Run /sbin/init as init process
ifconfig: SIOCSIFADDR: No such device
route: SIOCADDRT: Network is unreachable

But, ssh is still not working.
ssh root@localhost:2222
ssh: Could not resolve hostname localhost:2222: Name or service not known


2) if I give "-net nic" I get eth0 interface but still ssh does not work.
qemu-system-arm: warning: netdev unet has no peer
Booting Linux on physical CPU 0x0

3) With this there is no error, but still ssh not working
qemu-system-arm -M vexpress-a9 -m 1024M -kernel
../KERNEL/linux/arch/arm/boot/zImage -dtb
../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram
rdinit=/sbin/init" -nographic -netdev
user,id=net0,hostfwd=tcp::2222-:22 -device
virtio-net-device,netdev=net0 -net user -net nic

ssh root@localhost:2222
ssh: Could not resolve hostname localhost:2222: Name or service not known

4) I also followed the steps mentioned in the below document, but its
same result:
https://wiki.qemu.org/Documentation/Networking

-------------
So, I have some doubts:
- Do, I need anything to be configured on host PC as well ?
  I am using Ubuntu 16.04 desktop, and it is connected to only one
office LAN network
- Do I need any network configuration changes on host ?
- Do I need to enable any thing in kernel side ?
- I am using minimal busybox and I see there is no "ssh" command
there. Do I need a different busybox or a dropbear ?
- Will it work easily with buildroot ?
- Is there any precompiled arm32-rootfs image present somewhere, which
which ssh can work by default ?
  Because, I really don't care much about user side, so any arm-rootfs
should be fine for me
- I haven't really explored "bridge/tap" network yet. Is that worth to
try in these conditions.


Regards,
Pintu

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Re: ssh session with qemu-arm using busybox

[Suzuki K Poulose]

On 12/03/2019 14:02, Pintu Agarwal wrote:
>>
>> -netdev user,id=unet,hostfwd=tcp::2222-:22 \
>> -net user \
>>
>> and you 'll get guest's port 22 to be forwarded to hosts port 2222, so
>> you can do
>>
>> ssh root@localhost:2222
>>
>> from the host.
>>
> 
> I tried many different options, but unfortunately none worked for me.
> 1)
> qemu-system-arm -M vexpress-a9 -m 1024M -kernel
> ../KERNEL/linux/arch/arm/boot/zImage -dtb
> ../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
> rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram rdinit=/sbin/init
> ip=dhcp" -nographic -smp 4 -netdev user,id=unet,hostfwd=tcp::2222-:22
> -net user
> 
> With this the eth0 interface is removed, and I see this message
> (although login works):
> qemu-system-arm: warning: hub 0 with no nics
> qemu-system-arm: warning: netdev unet has no peer
> Booting Linux on physical CPU 0x0
> <skip>
> NET: Registered protocol family 17
> <skip>
> Run /sbin/init as init process
> ifconfig: SIOCSIFADDR: No such device
> route: SIOCADDRT: Network is unreachable
> 
> But, ssh is still not working.
> ssh root@localhost:2222
> ssh: Could not resolve hostname localhost:2222: Name or service not known

man ssh

+

Make sure you have sshd in your custom rootfs and has been stared.

Cheers
Suzuki

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Re: ssh session with qemu-arm using busybox

[Pintu Agarwal]

On Tue, Mar 12, 2019 at 7:41 PM Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
>
>
> On 12/03/2019 14:02, Pintu Agarwal wrote:
> >>
> >> -netdev user,id=unet,hostfwd=tcp::2222-:22 \
> >> -net user \
> >>
> >> and you 'll get guest's port 22 to be forwarded to hosts port 2222, so
> >> you can do
> >>
> >> ssh root@localhost:2222
> >>
> >> from the host.
> >>
> >
> > I tried many different options, but unfortunately none worked for me.
> > 1)
> > qemu-system-arm -M vexpress-a9 -m 1024M -kernel
> > ../KERNEL/linux/arch/arm/boot/zImage -dtb
> > ../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
> > rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram rdinit=/sbin/init
> > ip=dhcp" -nographic -smp 4 -netdev user,id=unet,hostfwd=tcp::2222-:22
> > -net user
> >
> > With this the eth0 interface is removed, and I see this message
> > (although login works):
> > qemu-system-arm: warning: hub 0 with no nics
> > qemu-system-arm: warning: netdev unet has no peer
> > Booting Linux on physical CPU 0x0
> > <skip>
> > NET: Registered protocol family 17
> > <skip>
> > Run /sbin/init as init process
> > ifconfig: SIOCSIFADDR: No such device
> > route: SIOCADDRT: Network is unreachable
> >
> > But, ssh is still not working.
> > ssh root@localhost:2222
> > ssh: Could not resolve hostname localhost:2222: Name or service not known
>
> man ssh
>
> +
>
> Make sure you have sshd in your custom rootfs and has been stared.
>

My busybox is a very minimal rootfs. It hardly contains any commands.
Is there any precompiled busybox for arm (cpio image), available (with
ssh, scp and networking in-built), which I can use directly to boot ?

what else I am missing to make ssh/scp working on qemu ?

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Re: [Qemu-devel] ssh session with qemu-arm using busybox

[Dongli Zhang]

On 3/13/19 1:08 AM, Pintu Agarwal wrote:
> On Tue, Mar 12, 2019 at 7:41 PM Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>>
>>
>>
>> On 12/03/2019 14:02, Pintu Agarwal wrote:
>>>>
>>>> -netdev user,id=unet,hostfwd=tcp::2222-:22 \
>>>> -net user \
>>>>
>>>> and you 'll get guest's port 22 to be forwarded to hosts port 2222, so
>>>> you can do
>>>>
>>>> ssh root@localhost:2222
>>>>
>>>> from the host.
>>>>
>>>
>>> I tried many different options, but unfortunately none worked for me.
>>> 1)
>>> qemu-system-arm -M vexpress-a9 -m 1024M -kernel
>>> ../KERNEL/linux/arch/arm/boot/zImage -dtb
>>> ../KERNEL/linux/arch/arm/boot/dts/vexpress-v2p-ca9.dtb -initrd
>>> rootfs.img.gz -append "console=ttyAMA0 root=/dev/ram rdinit=/sbin/init
>>> ip=dhcp" -nographic -smp 4 -netdev user,id=unet,hostfwd=tcp::2222-:22
>>> -net user
>>>
>>> With this the eth0 interface is removed, and I see this message
>>> (although login works):
>>> qemu-system-arm: warning: hub 0 with no nics
>>> qemu-system-arm: warning: netdev unet has no peer
>>> Booting Linux on physical CPU 0x0
>>> <skip>
>>> NET: Registered protocol family 17
>>> <skip>
>>> Run /sbin/init as init process
>>> ifconfig: SIOCSIFADDR: No such device
>>> route: SIOCADDRT: Network is unreachable
>>>
>>> But, ssh is still not working.
>>> ssh root@localhost:2222
>>> ssh: Could not resolve hostname localhost:2222: Name or service not known
>>
>> man ssh
>>
>> +
>>
>> Make sure you have sshd in your custom rootfs and has been stared.
>>
> 
> My busybox is a very minimal rootfs. It hardly contains any commands.
> Is there any precompiled busybox for arm (cpio image), available (with
> ssh, scp and networking in-built), which I can use directly to boot ?
> 
> what else I am missing to make ssh/scp working on qemu ?
> 

When I was working on arm binary rewriting/instrumentation in the university, I
use the image created by Linaro.

http://releases.linaro.org/

One example would be

https://www.linaro.org/blog/linaro-16-04-release-available-for-download-2/

or

https://releases.linaro.org/archive/ubuntu/images/developer-arm64/15.12/linaro-vivid-developer-20151215-114.tar.gz

The license should be good for academia. I do not know if there is any
restrictions on commercial/industry usage.

Thank for Linaro again for providing those images which helped me a lot when I
was in the university!

Dongli Zhang


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