diff --git a/src/libnm-glib-aux/nm-shared-utils.h b/src/libnm-glib-aux/nm-shared-utils.h
index aa6fdc70c7..d22a0d3572 100644
--- a/src/libnm-glib-aux/nm-shared-utils.h
+++ b/src/libnm-glib-aux/nm-shared-utils.h
@@ -2481,6 +2481,40 @@ nm_hexchar(int x, gboolean upper_case)
     return upper_case ? _nm_hexchar_table_upper[x & 15] : _nm_hexchar_table_lower[x & 15];
 }
 
+static inline gboolean
+nm_ascii_is_ctrl(char ch)
+{
+    /* 0 to ' '-1 is the C0 range.
+     *
+     * Other ranges may also be considered control characters, but NOT
+     * CONSIDERED by this function. For example:
+     *   - DEL (127) is also a control character.
+     *   - SP (' ', 0x20) is also considered a control character.
+     *   - DEL+1 (0x80) to 0x9F is C1 range.
+     *   - NBSP (0xA0) and SHY (0xAD) are ISO 8859 special characters
+     */
+    return ((guchar) ch) < ' ';
+}
+
+static inline gboolean
+nm_ascii_is_ctrl_or_del(char ch)
+{
+    return ((guchar) ch) < ' ' || ch == 127;
+}
+
+static inline gboolean
+nm_ascii_is_non_ascii(char ch)
+{
+    return ((guchar) ch) > 127;
+}
+
+static inline gboolean
+nm_ascii_is_regular(char ch)
+{
+    /* same as(!nm_ascii_is_ctrl_or_del(ch) && !nm_ascii_is_non_ascii(ch)) */
+    return ch >= ' ' && ch < 127;
+}
+
 char *nm_utils_bin2hexstr_full(gconstpointer addr,
                                gsize         length,
                                char          delimiter,
diff --git a/src/libnm-glib-aux/tests/test-shared-general.c b/src/libnm-glib-aux/tests/test-shared-general.c
index 593b8c42a1..98b98669bf 100644
--- a/src/libnm-glib-aux/tests/test-shared-general.c
+++ b/src/libnm-glib-aux/tests/test-shared-general.c
@@ -1370,6 +1370,49 @@ test_nm_g_source_sentinel(void)
 
 /*****************************************************************************/
 
+static void
+test_nm_ascii(void)
+{
+    int i;
+
+    for (i = 0; i < 256; i++) {
+        const char ch = i;
+        gboolean   is_space;
+
+        if (ch == 127) {
+            g_assert(nm_ascii_is_ctrl_or_del(ch));
+            g_assert(!nm_ascii_is_ctrl(ch));
+        } else
+            g_assert(nm_ascii_is_ctrl_or_del(ch) == nm_ascii_is_ctrl(ch));
+        g_assert(nm_ascii_is_ctrl_or_del(ch) == g_ascii_iscntrl(ch));
+
+        g_assert(nm_ascii_is_non_ascii(ch) == (i >= 128));
+
+        g_assert(!nm_ascii_is_ctrl_or_del(ch) || !nm_ascii_is_non_ascii(ch));
+
+        g_assert((nm_ascii_is_ctrl_or_del(ch) || nm_ascii_is_regular(ch))
+                 != nm_ascii_is_non_ascii(ch));
+
+        g_assert(nm_ascii_is_regular(ch)
+                 == (!nm_ascii_is_ctrl_or_del(ch) && !nm_ascii_is_non_ascii(ch)));
+
+        is_space = g_ascii_isspace(ch);
+        if (NM_IN_SET(ch, '\t', '\n', '\f', '\r')) {
+            /* hack is-space, so that the check below works to check for regular ASCII characters. */
+            g_assert(!nm_ascii_is_regular(ch));
+            g_assert(is_space);
+            is_space = FALSE;
+        }
+        g_assert(nm_ascii_is_regular(ch)
+                 == (g_ascii_isalnum(ch) || g_ascii_isalpha(ch) || g_ascii_isdigit(ch)
+                     || g_ascii_isgraph(ch) || g_ascii_islower(ch) || g_ascii_isprint(ch)
+                     || g_ascii_ispunct(ch) || is_space || g_ascii_isupper(ch)
+                     || g_ascii_isxdigit(ch)));
+    }
+}
+
+/*****************************************************************************/
+
 NMTST_DEFINE();
 
 int
@@ -1402,6 +1445,7 @@ main(int argc, char **argv)
     g_test_add_func("/general/test_strv_dup_packed", test_strv_dup_packed);
     g_test_add_func("/general/test_utils_hashtable_cmp", test_utils_hashtable_cmp);
     g_test_add_func("/general/test_nm_g_source_sentinel", test_nm_g_source_sentinel);
+    g_test_add_func("/general/test_nm_ascii", test_nm_ascii);
 
     return g_test_run();
 }