DEV Community: Jun wu

Capture VLAN tag with wireshark

Jun wu — Fri, 16 Dec 2022 11:59:31 +0000

Wireshark is widely used for Ethernet communication development.I have some projects need testing the Ethernet packets with & without VLAN tag. In this case, we need consider the following conditions for validation.

The publisher send the packets with/without VLAN tag
The Ethernet Switch can be setup to keep/remove the VLAN tag
The subscriber may see / not see the VLAN tag depend on the OS and driver configuration.

Typically wireshark is used as a validation tool. Here is the link from wireshark
https://wiki.wireshark.org/CaptureSetup/VLAN

My environment is windows + USB3 Ethernet Adapter (ASIX AX88179), there is an solution from the vendor to capture/keep VLAN tag in the driver:

Please set the "Packet Priority & VLAN" parameter of ASIX USB to LAN Windows drivers to "Packet Priority & VLAN Disable" to capture the VLAN tagged packets on WireShark.

How to print your log in VxWorks 6.x

Jun wu — Fri, 16 Dec 2022 11:36:59 +0000

Issue:

For embedded software developer using printf is the most used debug method on target. But in vxworks6.x, it start to change because the default stdout/stderr is redirected. If you connect to device by shell/telnet, printf in the code will not put to the stdout/stderr in the current shell.

Solution:

You can put a the following code in the debug version. Once you have connect to target by shell/telnet, call the function to redirect some task /all task io to the current shell.

void ioRedirect(void)
{
    int shellTid = 0;
    int shellOpFd = 0;
    int globalStdFd = 0;

    shellTid = taskIdSelf();
    shellOpFd = ioTaskStdGet(shellTid, 1);
    globalStdFd = ioGlobalStdGet(1);

    (void)logMsg("LM:Initial task output.shellFd %d, GlobalFd %d.\n", shellOpFd, globalStdFd, 0, 0, 0, 0);

    printf("p:Initial task output.shellFd %d, GlobalFd %d.\n", shellOpFd, globalStdFd);

    /*you can specify the task who need printf*/
    /*ioTaskStdSet(GSETaskId,1,shellOpFd);
    ioTaskStdSet(mstEvtId,1,shellOpFd);*/

    /*or set the global io*/
    ioGlobalStdSet(1, shellOpFd);
    globalStdFd = ioGlobalStdGet(1);

    logMsg("LM:Initial task output.shellFd %d, GlobalFd change to %d.\n", shellOpFd, globalStdFd, 0, 0, 0, 0);

    printf("p:Initial task output to globalStdFd %d.\n", globalStdFd);
}

Minikube on Ubuntu - Could Not Read CA certificate

Jun wu — Fri, 16 Dec 2022 11:25:49 +0000

Follow http://computerbryan.com/minikube-on-ubuntu.html

But with minor modifiton to the solution:
Add the following line to file /var/lib/snapd/apparmor/profiles/snap.docker.docker

owner @{HOME}/.minikube/certs/* r,