diff -r c3c188a0325a Lib/test/test_socket.py
--- a/Lib/test/test_socket.py	Thu Oct 11 17:22:45 2012 +0100
+++ b/Lib/test/test_socket.py	Thu Oct 11 09:52:49 2012 -0700
@@ -726,6 +726,19 @@
         if not fqhn in all_host_names:
             self.fail("Error testing host resolution mechanisms. (fqdn: %s, all: %s)" % (fqhn, repr(all_host_names)))
 
+    def testHostnameWhitespace(self):
+        hostnames = (
+                '127.0.0.1 ',
+                ' 127.0.0.1',
+                ' 127.0.0.1 ',
+                )
+        for hostname in hostnames:
+            try:
+                ip = socket.gethostbyname(hostname)
+            except socket.error:
+                self.fail('Failed to resolve %s' % hostname)
+            self.assertEqual(ip, '127.0.0.1')
+
     @unittest.skipUnless(hasattr(socket, 'sethostname'), "test needs socket.sethostname()")
     @unittest.skipUnless(hasattr(socket, 'gethostname'), "test needs socket.gethostname()")
     def test_sethostname(self):
diff -r c3c188a0325a Modules/socketmodule.c
--- a/Modules/socketmodule.c	Thu Oct 11 17:22:45 2012 +0100
+++ b/Modules/socketmodule.c	Thu Oct 11 09:52:49 2012 -0700
@@ -788,6 +788,29 @@
 #endif
 
 
+/* Convenient function to trim whitespace from a string input */
+static char *
+trimwhitespace(char *str)
+{
+    char *end, *cur;
+
+    cur = str;
+    while (isspace(*cur))
+        cur++;
+
+    if (*cur == '\0')   // str was ALL spaces
+        return str;     // do nothing - will fail socket.gethostbyname(' ')
+
+    end = cur + strlen(cur) - 1;
+    while (end > cur && isspace(*end))
+        end--;
+
+    *(end + 1) = '\0';
+
+    return cur;
+}
+
+
 /* Convert a string specifying a host name or one of a few symbolic
    names to a numeric IP address.  This usually calls gethostbyname()
    to do the work; the names "" and "<broadcast>" are special.
@@ -801,6 +824,9 @@
     int error;
     int d1, d2, d3, d4;
     char ch;
+    char *trimmed;
+
+    trimmed = trimwhitespace(name);
 
     memset((void *) addr_ret, '\0', sizeof(*addr_ret));
     if (name[0] == '\0') {
@@ -865,7 +891,7 @@
         sin->sin_addr.s_addr = INADDR_BROADCAST;
         return sizeof(sin->sin_addr);
     }
-    if (sscanf(name, "%d.%d.%d.%d%c", &d1, &d2, &d3, &d4, &ch) == 4 &&
+    if (sscanf(trimmed, "%d.%d.%d.%d%c", &d1, &d2, &d3, &d4, &ch) == 4 &&
         0 <= d1 && d1 <= 255 && 0 <= d2 && d2 <= 255 &&
         0 <= d3 && d3 <= 255 && 0 <= d4 && d4 <= 255) {
         struct sockaddr_in *sin;