I try to see the man page of the IP(7), but if I type in "man ip" then i get the IP(8) man page. My goal is to see the "struct sockaddr_in" struct.
Type man 7 ip at the prompt. As said in the man's manual
A section no, if provided, will direct man to look only in that section of
the manual.
Demo
$ man 7 ip
IP(7) Linux Programmer's Manual IP(7)
NAME
ip - Linux IPv4 protocol implementation
SYNOPSIS
#include <sys/socket.h>
.
.
.
.
And struct sockaddr_in here for you!
struct sockaddr_in {
sa_family_t sin_family; /* address family: AF_INET */
in_port_t sin_port; /* port in network byte order */
struct in_addr sin_addr; /* internet address */
};
You can additionally specify the section in the call to the man command:
man 7 ip
You could consult man's man page for that: man man :-) There you will find this variant:
man -K [-w|-W] [-S list] [-i|-I] [--regex] [section] term ...
Related
I copied the example code for the book TCP/IP Sockets in C from http://cs.ecs.baylor.edu/~donahoo/practical/CSockets/winsock.html and got it to compile on MinGW (without warnings by changing clntLen from unsigned int to int and void main to int main).
$ gcc.exe -Wall -o TCPEchoServerWS TCPEchoServerWS.c HandleTCPClientWS.c DieWithErrorWS.c -lws2_32
$ gcc.exe -o TCPEchoClientWS TCPEchoClientWS.c DieWithErrorWS.c -lws2_32
When I run the executables the server but not the client triggers a Windows firewall notification.
$ ./TCPEchoServerWS.exe 5000
inside for loop
$ ./TCPEchoClientWS.exe 169.1.1.1 "Echo this" 5000
connect() failed: 10060
The from printf debugging
for (;;) /* Run forever */
{
printf("inside for loop");
clntLen = sizeof(echoClntAddr);
if ((clntSock = accept(servSock, (struct sockaddr *) &echoClntAddr, &clntLen)) < 0)
DieWithError("accept() failed");
printf("Handling client %s\n", inet_ntoa(echoClntAddr.sin_addr));
it appears that the accept() never returns. I assume this is because it never has a connection to extract?? Any ideas please? I've also tried linking with -lwsock32, and disabling windows firewall.
It turns out that I was using the wrong IP (I just copied the one from the command it the book).
I just needed to use the IPv4 address from ipconfig as Remy suggested.
I'd just download Openindiana (OI-hipster-gui-20170502.iso)
and install it on my VirtualBox(5.1.22, macOS 10.12.5)
Two network interface enabled, one for NAT another for bridge(i want to use it in static ip)
# svcadm disable network/physical:nwam
# svcadm enable network/physical:default
# ipadm enable-if -t e1000g1
# ipadm create-addr -T static -a a.b.c.d/24 e1000g1/v4
ipadm: Could not create address: Persistent operation on temporary object
How can I configure it?
using Solaris11.3, i did
# ipadm create-ip net1
# ipadm create-addr -T static -a a.b.c.d/24 net1/v4
works fine.
Anybody tell me the difference between OpenIndiana(Illumos) and Solaris11
Best regards,
In a device driver source in the Linux tree, I saw dev_dbg(...) and dev_err(...), where do I find the logged message?
One reference suggest to add #define DEBUG . The other reference involves dynamic debug and debugfs, and I got lost.
dev_dbg() expands to dynamic_dev_dbg(), dev_printk(), or no-op depending on the compilation flags.
#if defined(CONFIG_DYNAMIC_DEBUG)
#define dev_dbg(dev, format, ...) \
do { \
dynamic_dev_dbg(dev, format, ##__VA_ARGS__); \
} while (0)
#elif defined(DEBUG)
#define dev_dbg(dev, format, arg...) \
dev_printk(KERN_DEBUG, dev, format, ##arg)
#else
#define dev_dbg(dev, format, arg...) \
({ \
if (0) \
dev_printk(KERN_DEBUG, dev, format, ##arg); \
})
#endif
dynamic_dev_dbg() and dev_printk() call dev_printk_emit() which calls vprintk_emit().
This very same function is called in a normal mode when you just do a printk(). Just note here, that the rest functions like dev_err() will end up in the same function.
Thus, obviously, the buffer is all the same, i.e. kernel intrenal buffer.
The logged message at the end is printed to
Current console if kernel loglevel value (can be changed via kernel command line or via procfs) is high enough for certain message, here KERN_DEBUG.
Internal buffer which can be read by running dmesg command.
Note, data in 2 is kept as long as there still room in the buffer. Since it's limited and circular, newer data preempts old one.
Additional information how to enable Dynamic Debug.
First of all, be sure you have CONFIG_DYNAMIC_DEBUG=y in the kernel configuration.
Assume we would like to enable all debug prints in the built-in module with name 8250. To achieve that we simple add to the kernel command line the following 8250.dyndbg=+p.
If the same driver is compiled as loadable module we may either add options 8250 dyndbg to the modprobe configuration or to the shell command line when do it manually, like modprobe 8250 dyndbg.
More details are described in the Dynamic Debug documentation.
The "How certain debug prints are automatically enabled in linux kernel?" raises the question why some debug prints are automatically enabled and how DEBUG affects that when CONFIG_DYNAMIC_DEBUG=y. The answer is lying in the dynamic_debug.h and since it's used during compilation the _DPRINTK_FLAGS_DEFAULT defines the certain message appearence.
#if defined DEBUG
#define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
#else
#define _DPRINTK_FLAGS_DEFAULT 0
#endif
you can find dev_err(...) in kernel messages. As the name implies, dev_err(...) messages are error messages, so they will definitely be printed if the execution comes to that point. dev_dbg(...) are debug messages which are more generously used in the kernel driver code and they are not printed by default. So everything you have read about dynamic_debugging comes into play with dev_dbg(...).
There are several pre-conditions to have dynamic debugging working, below 1. and 2. are general preconditions for dynamic debugging. 3. and later are for your particular driver/module/subsystem and can be .
Dynamic debugging support has to be in your kernel config CONFIG_DYNAMIC_DEBUG=y. You may check if it is the case zgrep DYNAMIC_DEBUG /proc/config.gz
debugfs has to be mounted. You can check with sudo mount | grep debugfs and if not existing, you can mount with sudo mount -t debugfs /sys/kernel/debug
refer to dynamic_debugging and enable the particular file/function/line you are interested
I have some Vxworks embedded os and I want to check the netstat.
This is what I tried:
-> inetstatShow
And the output is:
C interp: unknown symbol name 'inetstatShow'.
How can I have netstat command in this?
inetstatShow is provided by netShow library - you need to be sure that your OS configuration includes netShow, or you can dynamically load it using ld.
The lkup function can be used to list symbols that are available to the shell. Try lkup "Show" to list all symbols that include the sub-string "Show" for example.
VxWorks supports netstat command.
-> netstat "-n -a" /* state of sockets */
-> netstat "-n -r" /* routing table */
Following lots of "How to build your own Operating system" tutorials,
I'm supposed to write custom loader to floppy disk boot sector via
#include <sys/types.h> /* unistd.h needs this */
#include <unistd.h> /* contains read/write */
#include <fcntl.h>
int main()
{
char boot_buf[512];
int floppy_desc, file_desc;
file_desc = open("./boot", O_RDONLY);
read(file_desc, boot_buf, 510);
close(file_desc);
boot_buf[510] = 0x55;
boot_buf[511] = 0xaa;
floppy_desc = open("/dev/fd0", O_RDWR);
lseek(floppy_desc, 0, SEEK_CUR);
write(floppy_desc, boot_buf, 512);
close(floppy_desc);
}
I didn't have PC with floppy drive and I prefer to try whole of project on virtual machine via VirtualBox.
So How to write custom boot sector to a virtual CD image that will be invoked by my virtual machine ? :)
If you have any alternative way please suggest it :)
(note: this assumes you are on linux)
Instead of writing to /dev/fd0, which requires a real floppy drive, you could write to some a disk image which could be used to boot VirtualBox. However, you need to pad the file to 1.44MiB, since that's what the typical floppy is.
An even better way would be to first create the bootsector binary (with the 0xAA55 'magic code'), and then do something like dd if=MyBootsectorBin of=Floppy.flp bs=512 count=2880 to create the output file, Floppy.flp. This could be then booted via VirtualBox (or my preference, QEMU, via qemu -fda Floppy.flp).
I'm not sure about virtual CDs, but you can easily create an ISO to write to the disk. The required program for this is mkisofs, and more can be read about it from here.