diff --git a/Lib/netrc.py b/Lib/netrc.py
--- a/Lib/netrc.py
+++ b/Lib/netrc.py
@@ -2,7 +2,7 @@
 
 # Module and documentation by Eric S. Raymond, 21 Dec 1998
 
-import os, shlex
+import os, stat, shlex, pwd
 
 __all__ = ["netrc", "NetrcParseError"]
 
@@ -21,12 +21,31 @@
 
 class netrc:
     def __init__(self, file=None):
-        if file is None:
+        if file is not None:
+            fp = open(file)
+        else:
             try:
                 file = os.path.join(os.environ['HOME'], ".netrc")
             except KeyError:
                 raise IOError("Could not find .netrc: $HOME is not set")
-        fp = open(file)
+            fp = open(file)
+            if os.name == 'posix':
+                prop = os.fstat(fp.fileno())
+                if prop.st_uid != os.getuid():
+                    try:
+                        fowner = pwd.getpwuid(prop.st_uid)[0]
+                    except KeyError:
+                        fowner = 'uid %s' % prop.st_uid
+                    try:
+                        user = pwd.getpwuid(os.getuid())[0]
+                    except KeyError:
+                        user = 'uid %s ' % os.getuid()
+                    raise OSError("~/.netrc file owner (%s) does not match"
+                                  " current user (%s)" % (fowner, user))
+                if (prop.st_mode & (stat.S_IRWXG | stat.S_IRWXO)):
+                     raise OSError("~/.netrc access too permissive: access"
+                                   " permissions must restrict access to"
+                                   " only the owner")
         self.hosts = {}
         self.macros = {}
         lexer = shlex.shlex(fp)