diff --git a/configure.ac b/configure.ac
index 932a39ac..d373e94b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -493,6 +493,7 @@ AC_CONFIG_FILES([
   sesman/tools/Makefile
   tests/Makefile
   tests/common/Makefile
+  tests/libxrdp/Makefile
   tests/memtest/Makefile
   tests/xrdp/Makefile
   tools/Makefile
diff --git a/libxrdp/xrdp_sec.c b/libxrdp/xrdp_sec.c
index c5b34272..8fa34aea 100644
--- a/libxrdp/xrdp_sec.c
+++ b/libxrdp/xrdp_sec.c
@@ -2330,7 +2330,7 @@ xrdp_sec_process_mcs_data_channels(struct xrdp_sec *self, struct stream *s)
 /*****************************************************************************/
 /* Process a [MS-RDPBCGR] TS_UD_CS_MONITOR message.
    reads the client monitors data */
-static int
+int
 xrdp_sec_process_mcs_data_monitors(struct xrdp_sec *self, struct stream *s)
 {
     int index;
@@ -2374,7 +2374,7 @@ xrdp_sec_process_mcs_data_monitors(struct xrdp_sec *self, struct stream *s)
         LOG(LOG_LEVEL_ERROR,
             "[MS-RDPBCGR] Protocol error: TS_UD_CS_MONITOR monitorCount "
             "MUST be less than 16, received: %d", monitorCount);
-        return 1;
+        return 2;
     }
 
     client_info->monitorCount = monitorCount;
@@ -2468,7 +2468,7 @@ xrdp_sec_process_mcs_data_monitors(struct xrdp_sec *self, struct stream *s)
             "Allowed height range: min %d, max %d. Height received: %d",
             0xC8, 0x7FFE, client_info->width,
             0xC8, 0x7FFE, client_info->height);
-        return 1; /* error */
+        return 3; /* error */
     }
 
     /* keep a copy of non negative monitor info values for xrdp_wm usage */
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 42b0df1c..01ed83f2 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -4,5 +4,6 @@ EXTRA_DIST = \
 
 SUBDIRS = \
   common \
+  libxrdp \
   memtest \
   xrdp
diff --git a/tests/libxrdp/Makefile.am b/tests/libxrdp/Makefile.am
new file mode 100644
index 00000000..e98e8d9c
--- /dev/null
+++ b/tests/libxrdp/Makefile.am
@@ -0,0 +1,23 @@
+AM_CPPFLAGS = \
+  -I$(top_builddir) \
+  -I$(top_srcdir)/libxrdp \
+  -I$(top_srcdir)/common
+
+LOG_DRIVER = env AM_TAP_AWK='$(AWK)' $(SHELL) \
+                  $(top_srcdir)/tap-driver.sh
+
+TESTS = test_libxrdp
+check_PROGRAMS = test_libxrdp
+
+test_libxrdp_SOURCES = \
+    test_libxrdp.h \
+    test_libxrdp_main.c \
+    test_monitor_processing.c
+
+test_libxrdp_CFLAGS = \
+    @CHECK_CFLAGS@
+
+test_libxrdp_LDADD = \
+    $(top_builddir)/common/libcommon.la \
+    $(top_builddir)/libxrdp/libxrdp.la \
+    @CHECK_LIBS@
diff --git a/tests/libxrdp/test_libxrdp.h b/tests/libxrdp/test_libxrdp.h
new file mode 100644
index 00000000..444adf9e
--- /dev/null
+++ b/tests/libxrdp/test_libxrdp.h
@@ -0,0 +1,8 @@
+#ifndef TEST_LIBXRDP_H
+#define TEST_LIBXRDP_H
+
+#include <check.h>
+
+Suite *make_suite_test_monitor_processing(void);
+
+#endif /* TEST_LIBXRDP_H */
\ No newline at end of file
diff --git a/tests/libxrdp/test_libxrdp_main.c b/tests/libxrdp/test_libxrdp_main.c
new file mode 100644
index 00000000..0bd15cad
--- /dev/null
+++ b/tests/libxrdp/test_libxrdp_main.c
@@ -0,0 +1,22 @@
+#if defined(HAVE_CONFIG_H)
+#include "config_ac.h"
+#endif
+
+#include <stdlib.h>
+#include <check.h>
+#include "test_libxrdp.h"
+
+int main (void)
+{
+    int number_failed;
+    SRunner *sr;
+
+    sr = srunner_create (make_suite_test_monitor_processing());
+    //   srunner_add_suite(sr, make_list_suite());
+
+    srunner_set_tap(sr, "-");
+    srunner_run_all (sr, CK_ENV);
+    number_failed = srunner_ntests_failed(sr);
+    srunner_free(sr);
+    return (number_failed == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
+}
diff --git a/tests/libxrdp/test_monitor_processing.c b/tests/libxrdp/test_monitor_processing.c
new file mode 100644
index 00000000..969da780
--- /dev/null
+++ b/tests/libxrdp/test_monitor_processing.c
@@ -0,0 +1,305 @@
+#if defined(HAVE_CONFIG_H)
+#include "config_ac.h"
+#endif
+
+#include "test_libxrdp.h"
+#include "libxrdp.h"
+#include "os_calls.h"
+
+struct xrdp_sec *sec_layer;
+struct xrdp_rdp *rdp_layer;
+struct xrdp_session *session;
+
+int
+xrdp_sec_process_mcs_data_monitors(struct xrdp_sec *self, struct stream *s);
+
+void setup(void)
+{
+    rdp_layer = (struct xrdp_rdp *)g_malloc(sizeof(struct xrdp_rdp), 1);
+    session = (struct xrdp_session *)g_malloc(sizeof(struct xrdp_session), 1);
+    session->rdp = rdp_layer;
+    session->client_info = &(((struct xrdp_rdp *)session->rdp)->client_info);
+    session->client_info->multimon = 1;
+    sec_layer = (struct xrdp_sec *) g_malloc(sizeof(struct xrdp_sec), 1);
+    sec_layer->rdp_layer = rdp_layer;
+}
+
+void teardown(void)
+{
+    g_free(sec_layer);
+    g_free(session);
+    g_free(rdp_layer);
+}
+
+START_TEST(test_process_monitors__when_flags_is_not_zero__fail)
+{
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 8);
+
+    out_uint32_le(s, 1);
+    out_uint32_le(s, 0);
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 1);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__when_mounter_count_is_greater_than_sixteen__fail)
+{
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 8);
+
+    out_uint32_le(s, 0);
+    out_uint32_le(s, 17);
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 2);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__with_single_monitor_happy_path)
+{
+    struct xrdp_client_info *client_info = &(rdp_layer->client_info);
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 28);
+
+    out_uint32_le(s, 0); //flags
+    out_uint32_le(s, 1); //monitorCount
+
+    // Pretend we have a 4k monitor
+    out_uint32_le(s, 0); //monitor left
+    out_uint32_le(s, 0); //monitor top
+    out_uint32_le(s, 3840); //monitor right
+    out_uint32_le(s, 2160); //monitor bottom
+    out_uint32_le(s, 1); //is primary
+
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    //Verify function call passed.
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 0);
+
+    ck_assert_int_eq(client_info->monitorCount, 1);
+
+    // Verify normal monitor
+    ck_assert_int_eq(client_info->minfo[0].left, 0);
+    ck_assert_int_eq(client_info->minfo[0].top, 0);
+    ck_assert_int_eq(client_info->minfo[0].right, 3840);
+    ck_assert_int_eq(client_info->minfo[0].bottom, 2160);
+    ck_assert_int_eq(client_info->minfo[0].is_primary, 1);
+
+    // Verify normalized monitor
+    ck_assert_int_eq(client_info->minfo_wm[0].left, 0);
+    ck_assert_int_eq(client_info->minfo_wm[0].top, 0);
+    ck_assert_int_eq(client_info->minfo_wm[0].right, 3840);
+    ck_assert_int_eq(client_info->minfo_wm[0].bottom, 2160);
+    ck_assert_int_eq(client_info->minfo_wm[0].is_primary, 1);
+
+    // Verify geometry (+1 greater than )
+    ck_assert_int_eq(client_info->width, 3841);
+    ck_assert_int_eq(client_info->height, 2161);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__when_no_primary_monitor_is_specified_one_is_selected)
+{
+    struct xrdp_client_info *client_info = &(rdp_layer->client_info);
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 28);
+
+    out_uint32_le(s, 0); //flags
+    out_uint32_le(s, 1); //monitorCount
+
+    // Pretend we have a 4k monitor
+    out_uint32_le(s, 0); //monitor left
+    out_uint32_le(s, 0); //monitor top
+    out_uint32_le(s, 3840); //monitor right
+    out_uint32_le(s, 2160); //monitor bottom
+    out_uint32_le(s, 0); //is primary
+
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    //Verify function call passed.
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 0);
+
+    ck_assert_int_eq(client_info->monitorCount, 1);
+
+    // Verify normal monitor
+    ck_assert_int_eq(client_info->minfo[0].left, 0);
+    ck_assert_int_eq(client_info->minfo[0].top, 0);
+    ck_assert_int_eq(client_info->minfo[0].right, 3840);
+    ck_assert_int_eq(client_info->minfo[0].bottom, 2160);
+    ck_assert_int_eq(client_info->minfo[0].is_primary, 1);
+
+    // Verify normalized monitor
+    ck_assert_int_eq(client_info->minfo_wm[0].left, 0);
+    ck_assert_int_eq(client_info->minfo_wm[0].top, 0);
+    ck_assert_int_eq(client_info->minfo_wm[0].right, 3840);
+    ck_assert_int_eq(client_info->minfo_wm[0].bottom, 2160);
+    ck_assert_int_eq(client_info->minfo_wm[0].is_primary, 1);
+
+    // Verify geometry (+1 greater than )
+    ck_assert_int_eq(client_info->width, 3841);
+    ck_assert_int_eq(client_info->height, 2161);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__when_virtual_desktop_width_is_too_large)
+{
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 28);
+
+    out_uint32_le(s, 0); //flags
+    out_uint32_le(s, 1); //monitorCount
+
+    // Pretend we have a 4k monitor
+    out_uint32_le(s, 0); //monitor left
+    out_uint32_le(s, 0); //monitor top
+    out_uint32_le(s, 33000); //monitor right
+    out_uint32_le(s, 2160); //monitor bottom
+    out_uint32_le(s, 1); //is primary
+
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    //Verify function call passed.
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 3);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__when_virtual_desktop_width_is_too_small)
+{
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 28);
+
+    out_uint32_le(s, 0); //flags
+    out_uint32_le(s, 1); //monitorCount
+
+    // Pretend we have a 4k monitor
+    out_uint32_le(s, 0); //monitor left
+    out_uint32_le(s, 0); //monitor top
+    out_uint32_le(s, 100); //monitor right
+    out_uint32_le(s, 2160); //monitor bottom
+    out_uint32_le(s, 1); //is primary
+
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    //Verify function call passed.
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 3);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__when_virtual_desktop_height_is_too_large)
+{
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 28);
+
+    out_uint32_le(s, 0); //flags
+    out_uint32_le(s, 1); //monitorCount
+
+    // Pretend we have a 4k monitor
+    out_uint32_le(s, 0); //monitor left
+    out_uint32_le(s, 0); //monitor top
+    out_uint32_le(s, 3840); //monitor right
+    out_uint32_le(s, 33000); //monitor bottom
+    out_uint32_le(s, 1); //is primary
+
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    //Verify function call passed.
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 3);
+
+    free_stream(s);
+}
+END_TEST
+
+START_TEST(test_process_monitors__when_virtual_desktop_height_is_too_small)
+{
+    struct stream *s = (struct stream *)NULL;
+    make_stream(s);
+    init_stream(s, 28);
+
+    out_uint32_le(s, 0); //flags
+    out_uint32_le(s, 1); //monitorCount
+
+    // Pretend we have a 4k monitor
+    out_uint32_le(s, 0); //monitor left
+    out_uint32_le(s, 0); //monitor top
+    out_uint32_le(s, 3840); //monitor right
+    out_uint32_le(s, 100); //monitor bottom
+    out_uint32_le(s, 1); //is primary
+
+    s_mark_end(s);
+    //Reset the read counter of the stream so the processing function handles it properly.
+    s->p = s->data;
+
+    //Verify function call passed.
+    int error = xrdp_sec_process_mcs_data_monitors(sec_layer, s);
+    ck_assert_int_eq(error, 3);
+
+    free_stream(s);
+}
+END_TEST
+
+/******************************************************************************/
+Suite *
+make_suite_test_monitor_processing(void)
+{
+    Suite *s;
+    TCase *tc_process_monitors;
+
+    s = suite_create("Monitor_Processing");
+
+    tc_process_monitors = tcase_create("xrdp_sec_process_mcs_data_monitors");
+    tcase_add_checked_fixture(tc_process_monitors, setup, teardown);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_flags_is_not_zero__fail);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_mounter_count_is_greater_than_sixteen__fail);
+    tcase_add_test(tc_process_monitors, test_process_monitors__with_single_monitor_happy_path);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_no_primary_monitor_is_specified_one_is_selected);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_virtual_desktop_width_is_too_large);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_virtual_desktop_width_is_too_small);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_virtual_desktop_height_is_too_large);
+    tcase_add_test(tc_process_monitors, test_process_monitors__when_virtual_desktop_height_is_too_small);
+
+    suite_add_tcase(s, tc_process_monitors);
+
+    return s;
+}