WP7607-1 with Legato 21.05, tcp-server not working as expected

1

I have an old legato app running fine with legato 19.2 and yocto 3.18. Now with new generations of wp7607-1 modules I have to use legato 21.05 and linux 4.14. I was able to compile and install yocto with additional progs (openvpn) as I did with last version of legato dist-source (version 02.37.10.02). I was also able to run mksys which also included my app. The app leaved unchanged therefor.

One function of my app is a tcp-server. It ran without problems with modules using linux 3.18 and legato 19.2. Now the app starts as expected and does not show any error in logread but I can’t connect to the server anymore. I have a running openvpn-connection and I am able to ping to the device. I am also able to create a socat-tcp-server for a test and can connect to it but my app’s tcpserver is not usefull anymore.

I can see the server listening with netstat -a
tcp 0 0 0.0.0.0:xxxx 0.0.0.0:* LISTEN

It is no problem of firewall. The server is also not working with localhost or with all ports opened (iptables -A INPUT -j ACCEPT).

2

So is this related to particule port number as you said that you can create another tcp server port?

Did you capture wireshark log for investigation?

Does this help?

3

Hello,

No it is not related to a specific port number. It seems to be a problem with my new compiled app with current legato and / or linux 4.14.

I thought it could be a sandbox-problem but the app is currently not sandboxed.

4

Did you capture wireshark log for investigation?

Does this application help?

5

Hello,

I will add tcpdump to my system and try to capture packets.

6

You can also capture wireshark log on PC side

Btw, you can also try this app

7

With my older Wp7607-1 everything works fine. Also a server created with socat is responding. The tcp-server of my app does not even recognize a connection!

8

If the app above works, then you can port the app to your application

9

I started my apps tcpserver on port 9302 (and it is running):

root 2417 0.0 0.7 3196 1216 pts/0 S 12:37 0:00 ./tcpserver -p 9302 -t 900 start

I connected to a PC and used the local ecm0-interface for testing. I started socat with:

socat -v -d -d TCP-LISTEN:9302,fork TCP:localhost:9300

and opened firewall with:

iptables -A INPUT -j ACCEPT

On pc-side I startet

echo “bla” | nc 192.168.2.2 9300

socat told me:

2025/01/22 12:47:26 socat[3314] N listening on AF=2 0.0.0.0:9300
2025/01/22 12:47:33 socat[3314] N accepting connection from AF=2 192.168.2.3:50126 on AF=2 192.168.2.2:9300
2025/01/22 12:47:33 socat[3314] N forked off child process 3322
2025/01/22 12:47:33 socat[3314] N listening on AF=2 0.0.0.0:9300
2025/01/22 12:47:33 socat[3322] N opening connection to AF=2 127.0.0.1:9302
2025/01/22 12:49:42 socat[3322] E connect(5, AF=2 127.0.0.1:9302, 16): Connection timed out
2025/01/22 12:49:42 socat[3322] N exit(1)
2025/01/22 12:49:42 socat[3314] N childdied(): handling signal 17

loread tells me:

Jan 22 12:33:57 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2107]/tcpServer T=main | tcpserver.c _tcpServer_COMPONENT_INIT() 375 | TCP-Server
Jan 22 12:35:05 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2201]/tcpServer T=main | tcpserver.c _tcpServer_COMPONENT_INIT() 375 | TCP-Server
Jan 22 12:36:46 swi-mdm9x28-wp user.warn Legato: -WRN- | configTree[1238]/framework T=main | safeRef.c le_ref_CreateRef() 546 | Safe reference map maximum exceeded for refPathIteratorMap, new size 42
Jan 22 12:37:10 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2387]/tcpServer T=main | tcpserver.c _tcpServer_COMPONENT_INIT() 375 | TCP-Server
Jan 22 12:37:25 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2402]/tcpServer T=main | tcpserver.c _tcpServer_COMPONENT_INIT() 375 | TCP-Server
Jan 22 12:37:25 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2402]/tcpServer T=main | tcpserver.c Command() 329 | start server
Jan 22 12:37:25 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2402]/tcpServer T=main | tcpserver.c Command() 343 | Starte Server
Jan 22 12:37:25 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2402]/tcpServer T=main | tcpserver.c Command() 365 | TCP-Server is monitoring port 9302
Jan 22 12:37:31 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2417]/tcpServer T=main | tcpserver.c _tcpServer_COMPONENT_INIT() 375 | TCP-Server
Jan 22 12:37:31 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2417]/tcpServer T=main | tcpserver.c Command() 329 | start server
Jan 22 12:37:31 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2417]/tcpServer T=main | tcpserver.c Command() 343 | Starte Server
Jan 22 12:37:31 swi-mdm9x28-wp user.info Legato: INFO | tcpserver[2417]/tcpServer T=main | tcpserver.c Command() 365 | TCP-Server is monitoring port 9302
Jan 22 12:40:00 swi-mdm9x28-wp user.info kernel: [ 562.110601] device lo entered promiscuous mode
Jan 22 12:41:40 swi-mdm9x28-wp user.info kernel: [ 662.442168] device lo left promiscuous mode
Jan 22 12:42:24 swi-mdm9x28-wp user.info kernel: [ 706.100613] device lo entered promiscuous mode
Jan 22 12:42:30 swi-mdm9x28-wp user.info kernel: [ 711.946706] TCP: request_sock_TCP: Possible SYN flooding on port 9302. Dropping request. Check SNMP counters.
Jan 22 12:42:37 swi-mdm9x28-wp user.info kernel: [ 719.587200] device lo left promiscuous mode

10

I compiled and installed your app fwdownloader. It runs as expected. I can connect local with nc and see the echo of my messages.

11

Now i compared your server with mine:

I used
socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)
you use
socket(AF_INET, SOCK_STREAM, 0)

I used
if (listen(fd,0) < 0) …
you use
if (listen(fd,1) < 0) …

I changed the 2 lines. Additionally I had to remove the build-Directory to recompile all code. After that my server worked as expected.