Ytdyklly

I am trying to give an embedded router networking on QEMU. I replaced the router's kernel and modules using a generic buildroot build for the Malta CPU. I also can compile any software needed to help with figuring out what's wrong with the networking.

What is wrong with my network setup and how can I fix it so that my guest can connect to the internet and run servers (that I can port forward)?

Currently I can assign the router (QEMU Guest) an IP address, but I have to manually type in the IP I want. I am trying to either set the IP of the router to 192.168.76.9 or 192.168.76.10. I don't actually care what the IP address is, though.

-netdev user,id=use0,net=192.168.76.0/24,dhcpstart=192.168.76.9 -device pcnet,netdev=use0,mac=12:44:66:55:33:22 

-object filter-dump,id=use0,netdev=use0,file="$TCP_DUMP" 

The above QEMU arguments come from the start.command file.

I have dumped a log of my booting up and messing around with the router and of the network capture that QEMU saw (by using the object argument above).

This is the kernel finding the network card if a usable card is available (pcnet only afaict).

pcnet32: pcnet32.c:v1.35 21.Apr.2008 tsbogend@alpha.franken.de

PCI: Enabling device 0000:00:13.0 (0000 -> 0003)

pcnet32: PCnet/PCI II 79C970A at 0x1060, 12:44:66:55:33:22 assigned IRQ 10

pcnet32: eth0: registered as PCnet/PCI II 79C970A

pcnet32: 1 cards_found

I have to manually specify an ip address for ifconfig to add the eth0 device to the list of network devices.

# ifconfig eth0

eth0      Link encap:Ethernet  HWaddr 12:44:66:55:33:22  

          BROADCAST MULTICAST  MTU:1500  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)

          Interrupt:10 Base address:0x1060 

Busybox's udhcpc refuses to work without having eth0 already brought up and it cannot override what I set manually for the IP address. It can detect the DHCP settings that QEMU gives it. Not specifying -r IP_ADDRESS, it will pick a correct IP to use.

# ./busybox udhcpc -n -i eth0 -r 192.168.76.10

udhcpc: started, v1.29.3

udhcpc: sending discover

udhcpc: sendto: Network is down

udhcpc: read error: Network is down, reopening socket

I can bring the device online with both IPV4 and IPV6 although it will pick its own IPV6 address when I bring it online with IPV4.

# ifconfig eth0 192.168.76.10

pcnet32 0000:00:13.0 eth0: link up



# ifconfig eth0

eth0      Link encap:Ethernet  HWaddr 12:44:66:55:33:22  

          inet addr:192.168.76.10  Bcast:192.168.76.255  Mask:255.255.255.0

          inet6 addr: fe80::1044:66ff:fe55:3322/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:0 errors:0 dropped:0 overruns:0 frame:0

TX packets:7 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0           txqueuelen:1000           RX bytes:0 (0.0 B) TX bytes:826 (826.0 B)

          Interrupt:10 Base address:0x1060 

Here are two working DHCP leases after I bring up the eth0 device. They do not override the IP set when bring up the device.

# ./busybox udhcpc -n -i eth0 -r 192.168.76.10

udhcpc: started, v1.29.3

udhcpc: sending discover

udhcpc: sending select for 192.168.76.10

udhcpc: lease of 192.168.76.10 obtained, lease time 86400



# ./busybox udhcpc -n -i eth0

udhcpc: started, v1.29.3

udhcpc: sending discover

udhcpc: sending select for 192.168.76.9

udhcpc: lease of 192.168.76.9 obtained, lease time 86400

This is what the ip route looks like:

# ip route

192.168.76.0/24 dev eth0  proto kernel  scope link  src 192.168.76.9 



# ./busybox netstat -anr

Kernel IP routing table

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

192.168.76.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0

I have attempted to add a gateway to my routes. To be honest, I don't know what I am supposed to set as my QEMU gateway.

# route add default gw 192.168.76.1



# route -anr

Kernel IP routing table

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

0.0.0.0         192.168.76.1    0.0.0.0         UG        0 0          0 eth0

192.168.76.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0



# ip route show

default via 192.168.76.1 dev eth0 

192.168.76.0/24 dev eth0  proto kernel  scope link  src 192.168.76.9 

So, I am pretty sure I have the routing set up correctly (as I was trying to do according to this comment), but I have not succeeded in giving the router access to the internet. What's strange is, the tcp dump suggests that it should receive internet. I can use arp, dhcp, icmp, and icmp_v6.

# route add -host 192.168.76.1 dev eth0



# route -ne

Kernel IP routing table

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface

192.168.76.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0

192.168.76.1    0.0.0.0         255.255.255.255 UH        0 0          0 eth0

This is what the eth0 interface looks like using the ip command.

# ip addr show eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000

    link/ether 12:44:66:55:33:22 brd ff:ff:ff:ff:ff:ff

    inet 192.168.76.9/24 brd 192.168.76.255 scope global eth0

       valid_lft forever preferred_lft forever

    inet6 fe80::1044:66ff:fe55:3322/64 scope link 

       valid_lft forever preferred_lft forever

I don't know if the below error has anything to do with the networking in general, but trying to run a server results in the below error. The file is missing and it is not a regular file (it gives a different error code if I place a regular file here). I suspect this is supposed to link to a block device.

# telnetd

telnetd:error:12.536:oalMsg_init:121:connect to /var/smd_messaging_server_addr failed, rc=-1 errno=2

telnetd:error:12.540:cmsMdm_init:234:must pass in msgHandle

telnetd:error:12.541:main:538:Could not initialize MDM, ret=9003



# tftpd 

tftpd:error:23.520:oalMsg_init:121:connect to /var/smd_messaging_server_addr failed, rc=-1 errno=2

fatal: error during select, exit