Tera Term, Unexpected SSH2 message(80) on current stage(6) [was Re: SAP-2015-3-1 issues]

[Darren Tucker]

On Fri, Apr 10, 2015 at 04:45:56AM +0900, IWAMOTO Kouichi wrote:
> On Wed, 08 Apr 2015 21:28:53 -0500
> Bryan Drewery <bryan at shatow.net> wrote:
> 
> > This patch fixes it in OpenSSH for me:
> > 
> > https://people.freebsd.org/~bdrewery/patches/ttssh-host-keys.diff
> 
> In this change, hostkey rotation is not used if Tera Term supports it in future.
> Could you change a modification to the compat.c as follows?
> 
> --- compat.c.orig	2015-03-17 14:49:20.000000000 +0900
> +++ compat.c	2015-04-09 18:35:16.000000000 +0900
> @@ -167,6 +167,17 @@
>  					SSH_BUG_SCANNER },
>  		{ "Probe-*",
>  					SSH_BUG_PROBE },
> +		{ "TTSSH/1.5.*,"
> +		  "TeraTerm SSH*,"

Should this match all of TTSSH/1.* rather than just 1.5?  Also for
tidiness I'd rather keep the TTSSH entries grouped together and have the
compat check with the rest of the hostkey notification code rather than
inline with the main code.  Does this still work?

Also, we're nearly out of bug bits, we might have to order some more :-)

Index: compat.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/compat.c,v
retrieving revision 1.88
diff -u -p -r1.88 compat.c
--- compat.c	7 Apr 2015 23:00:42 -0000	1.88
+++ compat.c	10 Apr 2015 00:21:23 -0000
@@ -165,6 +165,17 @@ compat_datafellows(const char *version)
 					SSH_BUG_SCANNER },
 		{ "Probe-*",
 					SSH_BUG_PROBE },
+		{ "TeraTerm SSH*,"
+		  "TTSSH/1.5.*,"
+		  "TTSSH/2.1*,"
+		  "TTSSH/2.2*,"
+		  "TTSSH/2.3*,"
+		  "TTSSH/2.4*,"
+		  "TTSSH/2.5*,"
+		  "TTSSH/2.6*,"
+		  "TTSSH/2.70*,"
+		  "TTSSH/2.71*,"
+		  "TTSSH/2.72*",	SSH_BUG_HOSTKEYS },
 		{ NULL,			0 }
 	};
 
Index: compat.h
===================================================================
RCS file: /cvs/src/usr.bin/ssh/compat.h,v
retrieving revision 1.46
diff -u -p -r1.46 compat.h
--- compat.h	19 Jan 2015 20:20:20 -0000	1.46
+++ compat.h	10 Apr 2015 00:21:23 -0000
@@ -60,6 +60,7 @@
 #define SSH_NEW_OPENSSH		0x04000000
 #define SSH_BUG_DYNAMIC_RPORT	0x08000000
 #define SSH_BUG_CURVE25519PAD	0x10000000
+#define SSH_BUG_HOSTKEYS	0x20000000
 
 void     enable_compat13(void);
 void     enable_compat20(void);
Index: sshd.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/sshd.c,v
retrieving revision 1.445
diff -u -p -r1.445 sshd.c
--- sshd.c	31 Mar 2015 22:55:24 -0000	1.445
+++ sshd.c	10 Apr 2015 00:21:23 -0000
@@ -891,6 +891,10 @@ notify_hostkeys(struct ssh *ssh)
 	int i, nkeys, r;
 	char *fp;
 
+	/* Some clients cannot cope with the hostkeys message, skip those. */
+	if (datafellows & SSH_BUG_HOSTKEYS)
+		return;
+
 	if ((buf = sshbuf_new()) == NULL)
 		fatal("%s: sshbuf_new", __func__);
 	for (i = nkeys = 0; i < options.num_host_key_files; i++) {

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.