Cannot Connect to Dropbear Server of Openwrt in QEMU

[Matt Johnston]

Hi,

Given in tcpdump there was no response at all (not even a rejection), my guess is there is a firewall on the OpenWrt host that drops all port 22 packets.
Are firewall rules listed if you go "iptables -vnL" , or in a config file?

Cheers,
Matt

> On Tue 20/10/2020, at 1:50 pm, 许大仙 <xuyiwen14 at gmail.com> wrote:
> 
> Hi!
> Sorry to disturb you.
> I meet some problems when I try to connect  to Dropbear Server of Openwrt.
> So I really need your help.
> 
> Here's the thing:
> 1. I run QEMU with Openwrt(guest) for emulating an ARM system on ubuntu 18.04(host).
> Run the following commands on ubuntu 18.04:
> qemu-system-aarch64 -net nic,vlan=0 -net nic,vlan=1 -net user,vlan=1 \
> -m 1024 -smp 2 -cpu cortex-a57 -M virt -nographic \
> -kernel openwrt-19.07.3-armvirt-64-Image-initramfs \
> -drive if=none,file=disk.img,format=raw,id=hd0 \
> -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10021-:22 \
>  -net nic,model=e1000
> Details: https://openwrt.org/docs/guide-user/virtualization/qemu <https://openwrt.org/docs/guide-user/virtualization/qemu>.
> 
> 2. But I can not access dropbear of Openwrt through ssh in my host machine——ubuntu 18.04.
> SSH timeout:
> <image.png>
> Dropbear Service of Openwrt in QEMU:
> <image.png>
> 
> 3. I tried to use tcpdump to capture packages in Openwrt and found that dropbear did not respond to any data packet received on port 22.
> Captured packages:
> <image.png>
> 
> This is so strange. Could you give me some possible reasons?
> Under what circumstances will Dropbear not reply to the packet?
> 
> 
> Additional Information:
> 1. Config of dropbear
> <image.png>
> 2.  User Networking of QEMU
> https://wiki.qemu.org/Documentation/Networking <https://wiki.qemu.org/Documentation/Networking>
> <image.png>
> 

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