X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/1b15fedd1cb65a9d00c1d03bf7652e197006d19d..d2c7d4e92b665cb6dafe654e51a0b5baa487e6ed:/tcpdump.c?ds=sidebyside

diff --git a/tcpdump.c b/tcpdump.c
index 4e524082..c8da36ba 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -154,7 +154,6 @@ static struct printer printers[] = {
 #ifdef DLT_ARCNET_LINUX
 	{ arcnet_linux_if_print, DLT_ARCNET_LINUX },
 #endif
-	{ ether_if_print,	DLT_EN10MB },
 	{ token_if_print,	DLT_IEEE802 },
 #ifdef DLT_LANE8023
 	{ lane_if_print,        DLT_LANE8023 },
@@ -306,6 +305,7 @@ static struct printer printers[] = {
 };
 
 static struct ndo_printer ndo_printers[] = {
+	{ ether_if_print,	DLT_EN10MB },
 #ifdef DLT_IPNET
 	{ ipnet_if_print,	DLT_IPNET },
 #endif
@@ -1258,6 +1258,30 @@ main(int argc, char **argv)
 		(void)setsignal(SIGHUP, oldhandler);
 #endif /* WIN32 */
 
+#ifndef WIN32
+	/*
+	 * If a user name was specified with "-Z", attempt to switch to
+	 * that user's UID.  This would probably be used with sudo,
+	 * to allow tcpdump to be run in a special restricted
+	 * account (if you just want to allow users to open capture
+	 * devices, and can't just give users that permission,
+	 * you'd make tcpdump set-UID or set-GID).
+	 *
+	 * Tcpdump doesn't necessarily write only to one savefile;
+	 * the general only way to allow a -Z instance to write to
+	 * savefiles as the user under whose UID it's run, rather
+	 * than as the user specified with -Z, would thus be to switch
+	 * to the original user ID before opening a capture file and
+	 * then switch back to the -Z user ID after opening the savefile.
+	 * Switching to the -Z user ID only after opening the first
+	 * savefile doesn't handle the general case.
+	 */
+	if (getuid() == 0 || geteuid() == 0) {
+		if (username || chroot_dir)
+			droproot(username, chroot_dir);
+	}
+#endif /* WIN32 */
+
 	if (pcap_setfilter(pd, &fcode) < 0)
 		error("%s", pcap_geterr(pd));
 	if (WFileName) {
@@ -1311,16 +1335,7 @@ main(int argc, char **argv)
 		callback = print_packet;
 		pcap_userdata = (u_char *)&printinfo;
 	}
-#ifndef WIN32
-	/*
-	 * We cannot do this earlier, because we want to be able to open
-	 * the file (if done) for writing before giving up permissions.
-	 */
-	if (getuid() == 0 || geteuid() == 0) {
-		if (username || chroot_dir)
-			droproot(username, chroot_dir);
-	}
-#endif /* WIN32 */
+
 #ifdef SIGINFO
 	/*
 	 * We can't get statistics when reading from a file rather
@@ -1866,7 +1881,7 @@ usage(void)
 #endif /* WIN32 */
 #endif /* HAVE_PCAP_LIB_VERSION */
 	(void)fprintf(stderr,
-"Usage: %s [-aAbd" D_FLAG "ef" I_FLAG J_FLAG "KlLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [ -c count ]\n", program_name);
+"Usage: %s [-aAbd" D_FLAG "efh" I_FLAG J_FLAG "KlLnNOpqRStu" U_FLAG "vxX]" B_FLAG_USAGE " [ -c count ]\n", program_name);
 	(void)fprintf(stderr,
 "\t\t[ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]\n");
 	(void)fprintf(stderr,