diff --git a/fastrpc.cgi b/fastrpc.cgi
index aaa3af7cd..7872997d7 100755
--- a/fastrpc.cgi
+++ b/fastrpc.cgi
@@ -211,6 +211,12 @@ while(1) {
 			elsif ($use_ipv6 && vec($rmask, fileno($tsock6), 1)) {
 				accept(TRANS, $tsock6) || exit;
 				}
+			if ($arg->{'xferauth'}) {
+				my $auth = <TRANS>;
+				exit if (!defined($auth));
+				chomp($auth);
+				exit if ($auth ne $sid);
+				}
 			print STDERR "fastrpc[$$]: tcpwrite $file accepted\n" if ($gconfig{'rpcdebug'});
 			my $buf;
 			my $err;
@@ -240,7 +246,9 @@ while(1) {
 			$xfer_kids{$cpid} = 1;
 			print STDERR "fastrpc[$$]: tcpwrite $file started\n"
 				if ($gconfig{'rpcdebug'});
-			$rv = { 'status' => 1, 'rv' => [ $file, $tport ] };
+			$rv = { 'status' => 1,
+				'rv' => [ $file, $tport,
+					  $arg->{'xferauth'} ? $sid : undef ] };
 			}
 		close($tsock);
 		close($tsock6) if ($use_ipv6);
@@ -295,6 +303,12 @@ while(1) {
 				elsif (vec($rmask, fileno($tsock6), 1)) {
 					accept(TRANS, $tsock6) || exit;
 					}
+				if ($arg->{'xferauth'}) {
+					my $auth = <TRANS>;
+					exit if (!defined($auth));
+					chomp($auth);
+					exit if ($auth ne $sid);
+					}
 				my $buf;
 				while(read(FILE, $buf, 1024) > 0) {
 					print TRANS $buf;
@@ -309,7 +323,8 @@ while(1) {
 					     "started\n"
 					     	if ($gconfig{'rpcdebug'});
 				$rv = { 'status' => 1,
-					'rv' => [ $arg->{'file'}, $tport ] };
+					'rv' => [ $arg->{'file'}, $tport,
+						  $arg->{'xferauth'} ? $sid : undef ] };
 				}
 			close(FILE);
 			close($tsock);
diff --git a/web-lib-funcs.pl b/web-lib-funcs.pl
index d4fc5e997..6fb104e89 100755
--- a/web-lib-funcs.pl
+++ b/web-lib-funcs.pl
@@ -9020,12 +9020,14 @@ else {
 	my ($data, $got);
 	my $rv = &remote_rpc_call($host, { 'action' => 'tcpwrite',
 					   'file' => $remotefile,
-					   'name' => $remotebase } );
+					   'name' => $remotebase,
+					   'xferauth' => 1 } );
 	my $error;
 	my $serv = !ref($host) ? $host : ($host->{'ip'} || $host->{'host'});
 	&open_socket($serv || "localhost", $rv->[1], TWRITE, \$error);
 	return &$main::remote_error_handler("Failed to transfer file : $error")
 		if ($error);
+	print TWRITE $rv->[2],"\n" if ($rv->[2]);
 	open(FILE, "<".$localfile) ||
 		return &$main::remote_error_handler("Failed to open $localfile : $!");
 	my $bs = &get_buffer_size();
@@ -9072,7 +9074,8 @@ if ($sn eq "" && ref($s) && $s->{'local'}) {
 	}
 else {
 	my $rv = &remote_rpc_call($host, { 'action' => 'tcpread',
-					   'file' => $remotefile } );
+					   'file' => $remotefile,
+					   'xferauth' => 1 } );
 	if (!$rv->[0]) {
 		return &$main::remote_error_handler("Failed to transfer file : $rv->[1]");
 		}
@@ -9081,6 +9084,7 @@ else {
 	&open_socket($serv || "localhost", $rv->[1], TREAD, \$error);
 	return &$main::remote_error_handler("Failed to transfer file : $error")
 		if ($error);
+	print TREAD $rv->[2],"\n" if ($rv->[2]);
 	my $got;
 	open(FILE, ">$localfile") ||
 		return &$main::remote_error_handler("Failed to open $localfile : $!");