the code compiles correctly, but although I run the code with elevated privileges, I still have access denied.
I run the program like this: runas.exe / user: "admin" FlushIpNetTable.exe
OS: Windows 10 Version 10.0.10240
Does anyone have any suggestions why, despite the increased privileges, I cannot clean this table? :) ?
#include <winsock2.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib, "IPHLPAPI.lib")
int main() {
DWORD res, dwIndex;
dwIndex=2;
res = FlushIpNetTable(dwIndex);
if (res == ERROR_ACCESS_DENIED) {
printf("Access is denied.\n");
getchar();
exit(1);
} else if (res == ERROR_INVALID_PARAMETER) {
printf("An input parameter is invalid, no action was taken.\n");
getchar();
exit(1);
} else if (res == ERROR_NOT_SUPPORTED) {
printf("The IPv4 transport is not configured on the local computer.\n");
getchar();
exit(1);
}else {
printf("Use FormatMessage to obtain the message string for the returned error.\n");
getchar();
exit(1);
}
return 0;
}
Related
I wrote a simple program that check if a program run (e.g. Notepad). The compiled program should start in the Windows Task-Scheduler. Problem is, when I run my program normal, it works. When I run in Task-Scheduler it works too when I use the option: "Only run if the user is logged in". But when I use the option: "Execute independently of the user login" it doesn't work. My program can'tt find anything running programs (my program run, I can see in Task-Manager).
My Code:
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
void write_status(int state);
int isRunning(LPCSTR test);
int ret_val = 0;
int main(void)
{
while(1)
{
if(kbhit()) if(getch() == ' ') return 0;
Sleep(500);
ret_val = isRunning("Unbenannt - Editor");
printf("STATUS: %i\r", ret_val);
write_status(ret_val);
}
}
void write_status(int state)
{
FILE *fp = fopen("V:/ARAMAM.txt", "w");
if(state)
fprintf(fp, "ACTIVE ");
else
fprintf(fp, "NOT ACTIVE");
fclose(fp);
}
int isRunning(LPCSTR test)
{
HWND hwnd;
hwnd = FindWindowA(NULL, test);
if (hwnd != 0) {
return 1;
}
else {
return 0;
}
}
In the dont working case no console window shows. For this case i wrote the output in a external file. The writing in file works. Only find the running program fail.
My settings in Task-Scheduler, it's in German, sorry:
IMAGE
Can somebody help?
Umbrecht
I've read some of the warnings against using the sysctl() call in C, and it seems if I cannot use sysctl() safely, the only other way I can find to make the needed change would be to use soemething like:
system("echo fs.inotify.max_user_watches=NEW_MAX_DIRECTORIES >> /etc/sysctl.conf");
system("sysctl -p");
(of course, this assumes ensuring the binary is running as root. However, I would rather NOT have to shell out using system calls.
Can someone point me in the correct and safe of using sysctl()?
here is a snippet of the code I am using.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
#include <errno.h>
int main ()
{
int ret;
const char *LOGNAME="iNotifyMonitor";
logger(INFO, "================================================");
ret = startDaemon();
daemonRunning = ret;
if (ret == 0)
{
daemonRunning = 1;
FIRST_RUN = 0;
}
if(ret)
{
syslog(LOG_USER | LOG_ERR, "Error starting iNotifyMonitor");
logger(ERR, "Unable to start iNotifyMonitor");
closelog();
return EXIT_FAILURE;
}
signal(SIGINT, signalHandler);
signal(SIGHUP, signalHandler);
char *log_file_name = malloc(sizeof(char *) * sizeof(char *));
sprintf(log_file_name, "%s%s", INM_LOG_DIR, INM_LOG_FILE);
/* Try to open log file to this daemon */
if (INM_OPEN_LOG && INM_LOG_FILE)
{
log_stream = fopen(concatString(INM_LOG_DIR, INM_LOG_FILE), "a+");
if (log_stream == NULL)
{
char *errMsg;
sprintf(errMsg, "Cannot open log file %s, error: %s", concatString(INM_LOG_DIR, INM_LOG_FILE), strerror(errno));
log_stream = stdout;
}
}
else
{
log_stream = stdout;
}
while (daemonRunning == 1)
{
if (ret < 0)
{
logger(LOG_ERR, "Can not write to log stream: %s, error: %s", (log_stream == stdout) ? "stdout" : log_file_name, strerror(errno));
break;
}
ret = fflush(log_stream);
if (ret != 0)
{
logger(LOG_ERR, "Can not fflush() log stream: %s, error: %s",
(log_stream == stdout) ? "stdout" : log_file_name, strerror(errno));
break;
}
int curcount =countDirectory("/home/darrinw/Development/CrossRoads/");
directoryCount = curcount;
if(directoryCounrt > INM_MAX_DIRECTORIES)
{
int newVal = roundUp(directoryCount, 32768);
// call to sysctl() to modify fs.inotify.max_users_watches=newVal
}
sleep(INM_SCAN_INTERVAL);
}
My understanding is that the modern recommended approach to access sysctl variables is via the pseudo-files in /proc/sys. So just open /proc/sys/fs/inotify/max_user_watches and write there.
int fd = open("/proc/sys/fs/inotify/max_user_watches", O_WRONLY);
dprintf(fd, "%d", NEW_MAX_DIRECTORIES);
close(fd);
Error checking left as an exercise.
Modifying /etc/sysctl.conf would make the setting persist across reboots (assuming your distribution uses the file this way, I am not sure if all of them do). That's kind of rude to do automatically; probably better to use the documentation to advise the system administrator to do it themselves if it's needed.
I'm working on a C application in which I need the name of the currently logged in user. I have tried using getlogin() and getlogin_r() with no success (tested on multiple systems with Ubuntu 16.04 LTS). The application will run as root so I cannot use the environment variables.
Both getlogin() and getlogin_r() work just fine on other Ubuntu 17.04/17.10/18.04(beta) so I don't understand why it doesn't work in 16.04.
Here is a code snippet that I used to test:
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>
int main(int argc, char *argv[])
{
char user[512] = {0};
int ret = getlogin_r(user, 512);
if ( ret != 0){
fprintf(stderr, "Unable to get User name. Return: %d\n", ret);
}
else{
fprintf(stdout, "Username: %s\n", user);
}
char *lgn;
struct passwd *pw;
if ((lgn = getlogin()) == NULL || (pw = getpwnam(lgn)) == NULL)
{
fprintf(stderr, "Get of user information failed.\n");
}
struct passwd *pwd = getpwuid(getuid());
if (pwd){
fprintf(stdout, "Success! Username: %s\n", pwd->pw_name);
}else
fprintf(stderr, "Failed");
return 0;
}
This is the output generated when I execute the code as root:
Unable to get User name. Return : 2
Get of user information failed.
Success! Username: root
getpwuid returns the details of the user running the process so it is not helpful.
I'm kind of stuck now and any help is highly appreciated.
Output using strerror()
getlogin_r() : No such process
getlogin() : No such file or directory
Success! Username: root
My SSH server uses double authtication. I do not know how its implemented. But initially its asks for a password, then again asks for another password to login to a separate console which is different from usual control.
My code is similar to the example code shown in the documentations,
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <libssh/libssh.h>
int main(int argc, char * argv[])
{
ssh_session my_ssh_session = ssh_new();
int rc;
char * password;
char * username = "admin";
// Check if ssh session exists.
if(my_ssh_session == NULL)
{
exit(-1);
}
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, "x.x.x.x");
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
fprintf(stderr, "Error Connecting to Server: %s.\n", ssh_get_error(my_ssh_session));
exit(-1);
}
password = getpass("Password: ");
rc = ssh_userauth_password(my_ssh_session, username, password);
if (rc != SSH_AUTH_SUCCESS)
{
fprintf(stderr, "ERROR Authenticating: %s.\n", ssh_get_error(my_ssh_session));
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
}
else
{
printf("Authentication Successful.\n");
}
ssh_free(my_ssh_session);
}
How do i implement a double authtication in this ? can you kindly help me out ?
What version of
libssh do you have?
"versions 0.5.1 and above have a logical error in the handling of a SSH_MSG_NEWKEYS and SSH_MSG_KEXDH_REPLY package. A detected error did not set the session into the error state correctly and further processed the packet which leads to a null pointer dereference. This is the packet after the initial key exchange and doesn’t require authentication."
Ref libssh
after change user from root to nobody in c language, and I am sure the program core dump, but always can't generate core file.
I'm sure nobody have the right to generate file in current dir. and ulimit -c is unlimited, and I use :
system("echo 'tesstestestestestetestestet!!!!!!' > hahahahhaahahah");
after change user from root to nobody, the file hahahahhaahahah was created!
so, I'm very confuse!
here is my c file:
#include <pwd.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
int main()
{
#if 1
struct passwd *pw;
//char *username = "root";
char *username = "nobody";
if (getuid() == 0 || geteuid() == 0)
{
if (username == 0 || *username == '\0')
{
fprintf(stderr, "can't run as root without the -u switch\n");
exit(-1);
}
if ((pw = getpwnam(username)) == NULL)
{
fprintf(stderr, "can't find the user %s to switch to\n", username);
exit(-1);
}
if (setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
{
fprintf(stderr, "failed to assume identity of user %s\n", username);
exit(-1);
}
}
#endif
printf("now user change to group id %d, user id %d\n", getgid(), getuid());
system("echo 'tesstestestestestetestestet!!!!!!' > hahahahhaahahah");
char *test_a = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
char *test_b;
strcpy(test_b, test_a);
*(char *)1=1;
printf("test_b:%s\n", test_b);
}
Read carefully core(5) man page:
There are various circumstances in which a core dump file is not produced:
.... skipping some text from the man page ....
The process is executing a set-user-ID (set-group-ID) program that is owned by a user (group) other than the real user (group) ID of the process.
So basically, after a successful setuid(2) syscall, core is not dumped.(for security reasons)
See also the Linux specific prctl(2) syscall, with PR_SET_DUMPABLE.
Read also http://advancedlinuxprogramming.com/
NB. Have a nobody writable directory is probably a bad idea. The nobody user should usually not own any file or directory!