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When using tcpdump -I -i wlanN and wlanN is not a monitor mode VAP,

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tcpdump will print an error message saying rfmon is not supported.
Give a concise explanation as to how one might solve this problem by
creating a monitor mode VAP.
This commit is contained in:
Rui Paulo 2013-07-31 02:13:18 +00:00
parent d1da193810
commit 480d5cc8f7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=253827
1 changed files with 23 additions and 0 deletions
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23
contrib/tcpdump/tcpdump.c
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@ -71,6 +71,8 @@ extern int SIZE_BUF;
#ifdef __FreeBSD__
#include <sys/capability.h>
#include <sys/ioccom.h>
#include <sys/types.h>
#include <sys/sysctl.h>
#include <net/bpf.h>
#include <fcntl.h>
#include <libgen.h>
@ -1307,6 +1309,27 @@ main(int argc, char **argv)
*cp != '\0')
error("%s: %s\n(%s)", device,
pcap_statustostr(status), cp);
#ifdef __FreeBSD__
else if (status == PCAP_ERROR_RFMON_NOTSUP &&
strncmp(device, "wlan", 4) == 0) {
char parent[8], newdev[8];
char sysctl[32];
size_t s = sizeof(parent);
snprintf(sysctl, sizeof(sysctl),
"net.wlan.%d.%%parent", atoi(device + 4));
sysctlbyname(sysctl, parent, &s, NULL, 0);
strlcpy(newdev, device, sizeof(newdev));
/* Suggest a new wlan device. */
newdev[strlen(newdev)-1]++;
error("%s is not a monitor mode VAP\n"
"To create a new monitor mode VAP use:\n"
" ifconfig %s create wlandev %s wlanmode "
"monitor\nand use %s as the tcpdump "
"interface", device, newdev, parent,
newdev);
}
#endif
else
error("%s: %s", device,
pcap_statustostr(status));