    sudo tcpdump -i lo

### Notes
* If you get `tcpdump: lo: No such device exists`, get the name by coping it from the output of
```
sudo tcpdump -D
```
For example, if the output is as below you need `lo0` (which is reusult `9.` here:
```
1.en0 [Up, Running]
2.p2p0 [Up, Running]
3.awdl0 [Up, Running]
4.llw0 [Up, Running]
5.utun0 [Up, Running]
6.utun1 [Up, Running]
7.utun2 [Up, Running]
8.utun3 [Up, Running]
9.lo0 [Up, Running, Loopback]
```

Is there a difference between a &quot;parameter&quot; and an &quot;argument&quot;, or are they simply synonyms?

Difference between parameter and argument

&lt;pre&gt;Strict Standards: Declaration of childClass::customMethod() should be compatible with that of parentClass::customMethod()
&lt;/pre&gt;
What are possible causes of this error in PHP? Where can I find information about what it means to be *compatible*?

Declaration of Methods should be Compatible with Parent Methods in PHP

I write a program that send TCP packets from localhost to localhost. And I want to use tcpdump to capture the packets. But nothing is captured.
My command in Ubuntu:

    sudo tcpdump

What argument shall I add? Thanks!

tcpdump: localhost to localhost

<p>I write a program that send TCP packets from localhost to localhost. And I want to use tcpdump to capture the packets. But nothing is captured.
My command in Ubuntu:</p>
<pre><code class="hljs">sudo tcpdump
</code></pre>
<p>What argument shall I add? Thanks!</p>


I have the following data, and I need to put it all into one line.

I have this:

    22791
    
    ;
    
    14336
    
    ;
    
    22821
    
    ;
    
    34653
    
    ;
    
    21491
    
    ;
    
    25522
    
    ;
    
    33238
    
    ;

I need this:

    22791;14336;22821;34653;21491;25522;33238;


---------
# EDIT

None of these commands is working perfectly.

Most of them let the data look like this:

    22791
    
    ;14336
    
    ;22821
    
    ;34653
    
    ;21491
    
    ;25522


How do I remove newlines from a text file?

I have lines like these, and I want to know how many lines I actually have...

    09:16:39 AM  all    2.00    0.00    4.00    0.00    0.00    0.00    0.00    0.00   94.00
    09:16:40 AM  all    5.00    0.00    0.00    4.00    0.00    0.00    0.00    0.00   91.00
    09:16:41 AM  all    0.00    0.00    4.00    0.00    0.00    0.00    0.00    0.00   96.00
    09:16:42 AM  all    3.00    0.00    1.00    0.00    0.00    0.00    0.00    0.00   96.00
    09:16:43 AM  all    0.00    0.00    1.00    0.00    1.00    0.00    0.00    0.00   98.00
    09:16:44 AM  all    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
    09:16:45 AM  all    2.00    0.00    6.00    0.00    0.00    0.00    0.00    0.00   92.00

Is there a way to count them all using linux commands?


How to count lines in a document?

Using a function like this:

    #include &lt;stdio.h&gt;
    #include &lt;stdlib.h&gt;
    #include &lt;sys/wait.h&gt;
    #include &lt;unistd.h&gt;
    
    void print_trace() {
        char pid_buf[30];
        sprintf(pid_buf, &quot;--pid=%d&quot;, getpid());
        char name_buf[512];
        name_buf[readlink(&quot;/proc/self/exe&quot;, name_buf, 511)]=0;
        int child_pid = fork();
        if (!child_pid) {           
            dup2(2,1); // redirect output to stderr
            fprintf(stdout,&quot;stack trace for %s pid=%s\n&quot;,name_buf,pid_buf);
            execlp(&quot;gdb&quot;, &quot;gdb&quot;, &quot;--batch&quot;, &quot;-n&quot;, &quot;-ex&quot;, &quot;thread&quot;, &quot;-ex&quot;, &quot;bt&quot;, name_buf, pid_buf, NULL);
            abort(); /* If gdb failed to start */
        } else {
            waitpid(child_pid,NULL,0);
        }
    }


I see the details of print_trace in the output.

What are other ways to do it?

Best way to invoke gdb from inside program to print its stacktrace?

I&#39;ve a directory with many number of 0 byte files in it. I can&#39;t even see the files when I use the ls command. I&#39;m using a small script to delete these files but sometimes that does not even delete these files. Here is the script:

    i=100
    while [ $i -le 999 ];do
        rm -f file${i}*;
        let i++;
    done

Is there any other way to do this more quickly?

How to delete many 0 byte files in linux?

I have a `FILE *`, returned by a call to `fopen()`. I need to get a file descriptor from it, to make calls like `fsync(fd)` on it. What&#39;s the function to get a file descriptor from a file pointer?

How can I convert a file pointer ( FILE* fp ) to a file descriptor (int fd)?

I am working on a mobile website and would like to test it using my iPhone browser. My Windows 7 machine and iPhone are on the same wireless network. How do I access localhost from the iPhone? Right now I get a 404 error.

How do you access a website running on localhost from iPhone browser

I want to have a check in my javascript if the page loading up is on my local machine.

The reason why I want to do that is that when I developing I like to make sure that both my server side(C#) validation is working correctly. So I like to see both the client side and server sides errors to show up.


So while I am testing I have a flag in my jquery validate stuff that just always lets invalid data go through. This way I see the client side and server errors at one go.

However right now I have to manually go and change back and forth when going from development to production.



How to check with javascript if connection is local host?

I&#39;m developing a website using PHP and I want to make a human verification in one of the sessions. For the development, I&#39;m initially running the system locally and when it is ready, I&#39;m going to put it on some domain.

In the [reCAPTCHA website][1] it is said that the plugin will only work at the given domain (and subdomains).

Is there a way to use the reCAPTCHA plugin on a localhost?

  [1]: https://www.google.com/recaptcha/admin/create


Using reCAPTCHA on localhost

I was asked to set up HTTPS with a self-signed cert on Apache on localhost, but how do I actually do that? I have no idea at all.

How do I allow HTTPS for Apache on localhost?

I have to test out my new GA account on my local machine. 

Will this work just by copying the standard snippet supplied by Google onto the page &lt;head&gt;? 

I don&#39;t want to spend 24 hours waiting to see if it will or won&#39;t work.



Can you test google analytics on a localhost address?

I am using `tcpdump` to get HTTP data by executing the below command:   

    sudo tcpdump -A -s 1492 dst port 80

The result of above command:  

1. Headers, I think request and response headers.    
2. Unreadable data.   
3. The url `GET /modules/mod_news_pro_gk1/cache/stories.ilbalad.ajayeb.strange-tractor.jpg`.  

I need a more clear result, for example, readable request &gt; response header &gt; response body etc.
How can I filter my results?  

Can I use tcpdump to get HTTP requests, response header and response body?

I would like to monitor network traffic of my Android Phone. I was thinking using tcpdump for Android, but I&#39;m not sure if I have to cross-compile for the phone.

Another question is the following, If I want to monitor the trafic data for a certain application, there&#39;s any command for doing that?

Monitor network activity in Android Phones

I applied a filter in wireshark to display only the incoming packets to my PC. When I save the filtered/displayed packets to a .csv file, I actually saves all the packets (un-filtered). How can I save only the displayed/filtered packets?

Saving the displayed/filtered packets in wireshark

I want to have `tcpdump` write raw packet data into a file and also display packet analysis into standard output as the packets are captured (by analysis I mean the lines it displays normally when `-w` is missing).
Can anybody please tell me how to do that?

How can I have tcpdump write to file and standard output the appropriate data?

Each time, when I manually run `tcpdump`, I have to use &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;C&lt;/kbd&gt; to stop it. Now I want to schedule my `tcpdump` with cronjob and I only need it to run for 1 and half hours. Without manually running &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;C&lt;/kbd&gt; or kill command, how can it be stopped automatically? Here is the command I am testing:

    tcpdump -i eth0 &#39;port 8080&#39; -w  myfile

I can schedule another cronjob  to kill the `tcpdump` process, but it seems not a good idea. 

Content Type	Original Author	Original Content on Stackoverflow
Question	David	View Question on Stackoverflow
Solution 1 - Linux	unbeli	View Answer on Stackoverflow

tcpdump: localhost to localhost

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

Notes

Declaration of Methods should be Compatible with Parent Methods in PHP

Difference between parameter and argument

Attributions