Re: [lwip-users] lwip minimal example, echo server

[Matthias Dübon]

Hello again,

forget my last mail, I think I found something like a real reason for
the not working minimal example. After some debugging (starting with
the not working ARP resolution) I found that the netif flags are not
initialised in the mintapif_init in mintapif.c. After adding:

netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_IGMP;

everything is working fine.


best
Matthias


On Tue, Oct 7, 2014 at 12:39 PM, Matthias Dübon
<address@hidden> wrote:
> Hello Sergio,
>
> thanks for your support, I found my mistake, I changed the IP address
> from 192.168.0.2 to 172.168.0.2 because the 192.168.0.2 is already
> taken in my network. When using 192.168.5.2 everything is working
> fine. Hence I think I have to read something more about tap devices
> and default gateways.
>
> best
> Matthias
>
>
> On Fri, Oct 3, 2014 at 3:27 PM, Sergio R. Caprile <address@hidden> wrote:
>> OK, here I go...
>> The UN*X examples use a tun/tap device, and there is a specific
>> configuration parameter for different flavors of it. Check the Makefile
>> for this, did you ?
>> #To compile for linux: make ARCH=linux
>> #To compile for cygwin: make ARCH=cygwin
>> #To compile for openbsd: make ARCH=openbsd
>> ARCH=linux
>> Once you have the correct tun or tap device, it will show up in your
>> ifconfig and you will be able to ping the lwIP stack as a new machine on
>> a new network, which is what you should do first when debugging
>> networking problems.
>>
>> In main.c:
>>   /* startup defaults (may be overridden by one or more opts) */
>>   IP4_ADDR(&gw, 192,168,0,1);
>>   IP4_ADDR(&ipaddr, 192,168,0,2);
>>   IP4_ADDR(&netmask, 255,255,255,0);
>>
>> So, 192.168.0.1 will be the address of the gateway in your machine to
>> "the lwIP network", via a tun or tap interface. In Linux seems to be tap
>>
>> tap0      Link encap:Ethernet  HWaddr 86:99:D8:CE:27:DC
>>           inet addr:192.168.0.1  Bcast:192.168.0.255  Mask:255.255.255.0
>>           inet6 addr: fe80::8499:d8ff:fece:27dc/64 Scope:Link
>>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>>           TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
>>           collisions:0 txqueuelen:500
>>           RX bytes:0 (0.0 b)  TX bytes:468 (468.0 b)
>>
>> The specifics to get the tap working are beyond my knowledge, I remember
>> I just followed a tutorial. The interface will be up once the example is
>> running, and will dissappear after that.
>> Anyway, you should be able to ping that interface to check if the tap is
>> working.
>>
>> And, 192.168.0.2  will be your "lwIP machine" address, you should be
>> able to ping it
>>
>> address@hidden minimal]# ping 192.168.0.2
>> PING 192.168.0.2 (192.168.0.2) 56(84) bytes of data.
>> 64 bytes from 192.168.0.2: icmp_seq=1 ttl=255 time=8.76 ms
>> 64 bytes from 192.168.0.2: icmp_seq=2 ttl=255 time=9.66 ms
>>
>> --- 192.168.0.2 ping statistics ---
>> 2 packets transmitted, 2 received, 0% packet loss, time 999ms
>> rtt min/avg/max/mdev = 8.766/9.214/9.663/0.458 ms
>>
>> and you should be able to telnet to it in port 7, cause no one knows if
>> your
>>
>> SimpleEchoClient really works, although you probably will.
>>
>>
>> address@hidden minimal]# telnet 192.168.0.2 7
>> Trying 192.168.0.2...
>> Connected to 192.168.0.2.
>> Escape character is '^]'.
>> hola
>> hola
>>
>> You probably noticed I run this as root... there are some permissions
>> associated to the tap interface, and I'm lazy enough to change them.
>> Anyway, you should see something like this:
>> tapif: tapif_init: open: Permission denied
>> if that is the case.
>>
>>
>>
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>
> ᐧ

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