diff --git a/xCAT-server/lib/xcat/plugins/dhcp.pm b/xCAT-server/lib/xcat/plugins/dhcp.pm
index f4006937e..f7281552f 100644
--- a/xCAT-server/lib/xcat/plugins/dhcp.pm
+++ b/xCAT-server/lib/xcat/plugins/dhcp.pm
@@ -540,7 +540,7 @@ sub process_request
     }
 
    my $dhcplockfd;
-   open($dhcplockfd,"/tmp/xcat/dhcplock");
+   open($dhcplockfd,">","/tmp/xcat/dhcplock");
    flock($dhcplockfd,LOCK_EX);
    if (grep /^-n$/, @{$req->{arg}})
     {
diff --git a/xCAT-server/lib/xcat/plugins/hosts.pm b/xCAT-server/lib/xcat/plugins/hosts.pm
index cb6d2ce39..05f7f7ada 100644
--- a/xCAT-server/lib/xcat/plugins/hosts.pm
+++ b/xCAT-server/lib/xcat/plugins/hosts.pm
@@ -6,6 +6,7 @@ use xCAT::Table;
 use Data::Dumper;
 use File::Copy;
 use Getopt::Long;
+use Fcntl ':flock';
 
 
 my @hosts; #Hold /etc/hosts data to be written back
@@ -159,6 +160,7 @@ sub process_request {
   my $hoststab = xCAT::Table->new('hosts');
   my $sitetab = xCAT::Table->new('site');
   my $domain;
+  my $lockh;
   if ($sitetab) {
     my $dent = $sitetab->getAttribs({key=>'domain'},'value');
     if ($dent and $dent->{value}) {
@@ -177,6 +179,8 @@ sub process_request {
       my $bakname = "/etc/hosts.xcatbak";
       copy("/etc/hosts",$bakname);
     }
+    open($lockh,">","/tmp/xcat/hostsfile.lock");
+    flock($lockh,LOCK_EX);
     my $rconf;
     open($rconf,"/etc/hosts"); # Read file into memory
     if ($rconf) {
@@ -213,6 +217,7 @@ sub process_request {
     }
   }
   writeout();
+  flock($lockh,LOCK_UN);
 }