diff --git a/Makefile b/Makefile
index 0c31815..d2190f4 100644
--- a/Makefile
+++ b/Makefile
@@ -3,8 +3,8 @@
 
 include config.mk
 
-SRC = sis.c imap.c utils.c
-HDR = config.def.h imap.h utils.h imap.routines
+SRC = sis.c imap.c auth.c utils.c
+HDR = config.def.h imap.h auth.h utils.h imap.routines
 OBJ = ${SRC:.c=.o}
 
 all: options sis
diff --git a/auth.c b/auth.c
new file mode 100644
index 0000000..4da3ce7
--- /dev/null
+++ b/auth.c
@@ -0,0 +1,37 @@
+/*-
+ * Copyright (c) 2024, Lorenzo Torres
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the <organization> nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef AUTH_PAM
+
+int pam_conv_func(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr) {
+}
+
+uint8_t auth_pam(char *username, char *password)
+{
+}
+
+#endif
diff --git a/auth.h b/auth.h
new file mode 100644
index 0000000..8fd3ffc
--- /dev/null
+++ b/auth.h
@@ -0,0 +1,43 @@
+/*-
+ * Copyright (c) 2024, Lorenzo Torres
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the <organization> nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef AUTH_H
+#define AUTH_H
+
+#define AUTH_OK     0x1
+#define AUTH_FAIL   0x1 << 1
+
+#ifdef AUTH_PAM
+#include <security/pam_appl.h>
+#include <security/pam_modules.h>
+#include <security/pam_ext.h>
+
+uint8_t auth_pam(char *username, char *password);
+
+#endif
+
+#endif
diff --git a/config.def.h b/config.def.h
index e4eb0c8..cf5acd2 100644
--- a/config.def.h
+++ b/config.def.h
@@ -21,6 +21,11 @@
  * modify this.
  */
 #define CMD_MAX_SIZE    8000
+/*-
+ * Use pam (Pluggable Authentication Modules)
+ * as an authentication method
+ */
+#define AUTH_PAM
 
 static char *imap_capabilities[] = {
     "IMAP4rev1",
diff --git a/config.mk b/config.mk
index 518989f..a4e6864 100644
--- a/config.mk
+++ b/config.mk
@@ -15,7 +15,7 @@ INCS = -I.
 LIBS = -lssl -lcrypto
 # flags
 CPPFLAGS = -DVERSION=\"${VERSION}\" 
-CFLAGS  := -std=c99 -pedantic -Wall -O0 -Wno-gnu-label-as-value -Wno-gnu-zero-variadic-macro-arguments ${INCS} ${CPPFLAGS} 
+CFLAGS  := -std=gnu99 -pedantic -Wall -O0 -Wno-gnu-label-as-value -Wno-gnu-zero-variadic-macro-arguments ${INCS} ${CPPFLAGS} 
 CFLAGS  := ${CFLAGS} -g
 LDFLAGS  = ${LIBS}
 
diff --git a/imap.c b/imap.c
index 55b4cab..7987eb5 100644
--- a/imap.c
+++ b/imap.c
@@ -35,6 +35,7 @@
 #include <syslog.h>
 #include <errno.h>
 #include <config.h>
+#include <ctype.h>
 #include <utils.h>
 #include <imap.h>
 
@@ -370,10 +371,11 @@ uint8_t imap_match_cmd(char *cmd, size_t len)
 
 imap_cmd imap_parse_cmd(char *s)
 {
+    char *cpy;
     imap_cmd cmd;
     strstrip(s);
     size_t params = 0, id_len = 0, i = 0;
-    char *cpy;
+
     printf("%s\n", s);
 
     cmd.params = NULL;    
@@ -393,6 +395,9 @@ imap_cmd imap_parse_cmd(char *s)
 
     id_len -= 1;
     s -= id_len+1;
+
+    cpy = s;
+    for (; (cpy-s) <= id_len; ++cpy) *cpy = tolower(*cpy);
     cmd.id = imap_match_cmd(s, id_len);
     s += id_len+2;
 
diff --git a/imap.routines b/imap.routines
index f334e9b..ce74423 100644
--- a/imap.routines
+++ b/imap.routines
@@ -16,6 +16,8 @@ name: { \
 #define IMAP_ROUTINE_END imap_flush(node, ssl);
 #define IMAP_ROUTINE_OK(routine) \
     imap_write(node, ssl, "%s OK " #routine " completed\n", cmd.tag);
+#define IMAP_ROUTINE_NO(routine) \
+    imap_write(node, ssl, "%s NO " #routine " completed\n", cmd.tag);
 #define IMAP_STRING(fmt, ...) \
     imap_write(node, ssl, fmt, ##__VA_ARGS__);
 #define IMAP_NLINE imap_write(node, ssl, "\n");
@@ -77,7 +79,7 @@ static inline uint8_t imap_routine_auth(imap_cmd cmd, client_list *node, uint8_t
 
     int bytes;
 
-    if (strcmp(cmd.params[0], "PLAIN") == 0) {
+    if (strcmp(cmd.params[0], "plain") == 0) {
         IMAP_STRING("+\n");
         if ((bytes = imap_read(node, buf, CMD_MAX_SIZE, ssl)) < 0) {
             perror("recv");
@@ -98,5 +100,15 @@ static inline uint8_t imap_routine_auth(imap_cmd cmd, client_list *node, uint8_t
 
 static inline uint8_t imap_routine_login(imap_cmd cmd, client_list *node, uint8_t ssl, uint8_t state)
 {
+    IMAP_CHECK_STATE(NO_AUTH)
+    IMAP_CHECK_ARGS(2)
+
+    if ((strcmp(cmd.params[0], "lorenzo") == 0) && (strcmp(cmd.params[1], "lorenzo06") == 0)) {
+        IMAP_ROUTINE_OK(LOGIN)
+    } else {
+        IMAP_ROUTINE_NO(LOGIN)
+    }
+    
+    IMAP_ROUTINE_END
     return IMAP_SUCCESS;
 }