snake-os/dropbear-weakkex.diff at master · vanaware/snake-os · GitHub

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diff -ur dropbear-2012.55/algo.h dropbear-2012.55-new/algo.h
--- dropbear-2012.55/algo.h	2012-02-23 14:47:05.000000000 +0100
+++ dropbear-2012.55-new/algo.h	2012-08-29 00:31:50.193120988 +0200
@@ -47,6 +47,7 @@

 /* lists mapping ssh types of algorithms to internal values */
 extern algo_type sshkex[];
+extern algo_type sshkex_weak[];
 extern algo_type sshhostkey[];
 extern algo_type sshciphers[];
 extern algo_type sshhashes[];
diff -ur dropbear-2012.55/common-algo.c dropbear-2012.55-new/common-algo.c
--- dropbear-2012.55/common-algo.c	2012-02-23 14:47:05.000000000 +0100
+++ dropbear-2012.55-new/common-algo.c	2012-08-29 00:29:59.020120965 +0200
@@ -192,6 +192,11 @@
 	{NULL, 0, NULL, 0, NULL}
 };

+algo_type sshkex_weak[] = {
+	{"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1, NULL},
+	{NULL, 0, NULL, 0, NULL}
+};
+
 algo_type sshkex[] = {
 	{"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1, NULL},
 	{"diffie-hellman-group14-sha1", DROPBEAR_KEX_DH_GROUP14, NULL, 1, NULL},
diff -ur dropbear-2012.55/common-kex.c dropbear-2012.55-new/common-kex.c
--- dropbear-2012.55/common-kex.c	2012-02-23 14:47:05.000000000 +0100
+++ dropbear-2012.55-new/common-kex.c	2012-08-29 00:37:12.386121162 +0200
@@ -101,7 +101,7 @@
 	buf_incrwritepos(ses.writepayload, 16);

 	/* kex algos */
-	buf_put_algolist(ses.writepayload, sshkex);
+	buf_put_algolist(ses.writepayload, (opts.weakkex ? sshkex_weak : sshkex));

 	/* server_host_key_algorithms */
 	buf_put_algolist(ses.writepayload, sshhostkey);
@@ -671,7 +671,7 @@
 	ses.newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));

 	/* kex_algorithms */
-	algo = ses.buf_match_algo(ses.payload, sshkex, &goodguess);
+	algo = ses.buf_match_algo(ses.payload, (opts.weakkex ? sshkex_weak : sshkex), &goodguess);
 	allgood &= goodguess;
 	if (algo == NULL) {
 		erralgo = "kex";
diff -ur dropbear-2012.55/runopts.h dropbear-2012.55-new/runopts.h
--- dropbear-2012.55/runopts.h	2012-02-23 14:47:06.000000000 +0100
+++ dropbear-2012.55-new/runopts.h	2012-08-29 00:42:30.929121249 +0200
@@ -46,7 +46,7 @@
 	 * intermediate stages are compressed streams, so are uncompressible. */
 	int enable_compress;
 #endif
-
+	int weakkex;

 } runopts;

Nur in dropbear-2012.55-new/: runopts.h~.
diff -ur dropbear-2012.55/svr-runopts.c dropbear-2012.55-new/svr-runopts.c
--- dropbear-2012.55/svr-runopts.c	2012-02-23 14:47:06.000000000 +0100
+++ dropbear-2012.55-new/svr-runopts.c	2012-08-29 00:35:37.716121195 +0200
@@ -146,6 +146,8 @@
 	opts.listen_fwd_all = 0;
 #endif

+	opts.weakkex = 0;
+
 	for (i = 1; i < (unsigned int)argc; i++) {
 		if (nextisport) {
 			addportandaddress(argv[i]);
@@ -247,6 +249,9 @@
 					debug_trace = 1;
 					break;
 #endif
+				case 'x':
+					opts.weakkex = 1;
+					break;
 				default:
 					fprintf(stderr, "Unknown argument %s\n", argv[i]);
 					printhelp(argv[0]);