--- a/common-algo.c	Fri Jan 23 22:23:23 2015 +0800
+++ b/common-algo.c	Fri Jan 23 22:37:14 2015 +0800
@@ -84,10 +84,14 @@
 
 /* A few void* s are required to silence warnings
  * about the symmetric_CBC vs symmetric_CTR cipher_state pointer */
+#ifdef DROPBEAR_ENABLE_CBC_MODE
 const struct dropbear_cipher_mode dropbear_mode_cbc =
 	{(void*)cbc_start, (void*)cbc_encrypt, (void*)cbc_decrypt};
+#endif // DROPBEAR_ENABLE_CBC_MODE
+
 const struct dropbear_cipher_mode dropbear_mode_none =
 	{void_start, void_cipher, void_cipher};
+
 #ifdef DROPBEAR_ENABLE_CTR_MODE
 /* a wrapper to make ctr_start and cbc_start look the same */
 static int dropbear_big_endian_ctr_start(int cipher, 
@@ -98,7 +102,7 @@
 }
 const struct dropbear_cipher_mode dropbear_mode_ctr =
 	{(void*)dropbear_big_endian_ctr_start, (void*)ctr_encrypt, (void*)ctr_decrypt};
-#endif
+#endif // DROPBEAR_ENABLE_CTR_MODE
 
 /* Mapping of ssh hashes to libtomcrypt hashes, including keysize etc.
    {&hash_desc, keysize, hashsize} */
@@ -145,7 +149,7 @@
 #endif
 #endif /* DROPBEAR_ENABLE_CTR_MODE */
 
-/* CBC modes are always enabled */
+#ifdef DROPBEAR_ENABLE_CBC_MODE
 #ifdef DROPBEAR_AES128
 	{"aes128-cbc", 0, &dropbear_aes128, 1, &dropbear_mode_cbc},
 #endif
@@ -165,6 +169,7 @@
 #ifdef DROPBEAR_BLOWFISH
 	{"blowfish-cbc", 0, &dropbear_blowfish, 1, &dropbear_mode_cbc},
 #endif
+#endif /* DROPBEAR_ENABLE_CBC_MODE */
 #ifdef DROPBEAR_NONE_CIPHER
 	{"none", 0, (void*)&dropbear_nocipher, 1, &dropbear_mode_none},
 #endif

--- a/options.h	Fri Jan 23 22:23:23 2015 +0800
+++ b/options.h	Fri Jan 23 22:37:14 2015 +0800
@@ -95,8 +95,12 @@
 #define DROPBEAR_AES256
 /* Compiling in Blowfish will add ~6kB to runtime heap memory usage */
 /*#define DROPBEAR_BLOWFISH*/
-#define DROPBEAR_TWOFISH256
-#define DROPBEAR_TWOFISH128
+/*#define DROPBEAR_TWOFISH256*/
+/*#define DROPBEAR_TWOFISH128*/
+
+/* Enable CBC mode for ciphers. This has security issues though
+ * is the most compatible with older SSH implementations */
+#define DROPBEAR_ENABLE_CBC_MODE
 
 /* Enable "Counter Mode" for ciphers. This is more secure than normal
  * CBC mode against certain attacks. This adds around 1kB to binary