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Date:      Tue,  5 Dec 2000 01:14:07 +0100 (CET)
From:      sec@ice.42.org
To:        FreeBSD-gnats-submit@freebsd.org
Subject:   bin/23286: openssh is too verbose
Message-ID:  <20001205001407.B834DF9@ice.42.org>
Resent-Message-ID: <200012050020.eB50K0l32129@freefall.freebsd.org>

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>Number:         23286
>Category:       bin
>Synopsis:       openssh is too verbose
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Mon Dec 04 16:20:00 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Stefan `Sec` Zehl
>Release:        FreeBSD 4.1-STABLE i386
>Organization:
>Environment:

	

>Description:

The ssh binary in the FreeBSD base distribution is too verbose.
When ssh'ing to an host running an old ssh version it outputs:

| Warning: Server lies about size of server host key: actual size is 1023 bits vs. announced 1024.
| Warning: This may be due to an old implementation of ssh.

This has several problems:
- It is not possible to disable this without disabling ALL warnings.
  Disabling ALL warnings is obviously not a good idea for security related
  products
- It outputs this even in non-interactive mode, so I'm forced to modify
  automatic scrips to cater for this behaviour. This way the FreeBSD-4.x
  ssh is gratitously incompatible to older versions.
- If users get exposed to meaningless warnings they quickly learn to ignore
  warnings. This is obviosly a bad idea, as we want them to notice in case
  there is somthing we really need to warn the user about.

>How-To-Repeat:

ssh to an host with an old keysize length.

>Fix:

Cater explicitly for the 'one-bit-defference' case, and remove that now
meaningless 'This may be due to an old implementation' line.

--- /usr/src/crypto/openssh/sshconnect1.c.orig	Tue Dec  5 00:44:27 2000
+++ /usr/src/crypto/openssh/sshconnect1.c	Tue Dec  5 00:44:27 2000
@@ -744,9 +744,9 @@
 
 	rbits = BN_num_bits(host_key->n);
 	if (bits != rbits) {
+		if (rbits+1 != bits)
 		log("Warning: Server lies about size of server host key: "
 		    "actual size is %d bits vs. announced %d.", rbits, bits);
-		log("Warning: This may be due to an old implementation of ssh.");
 	}
 
 	/* Get protocol flags. */
	


>Release-Note:
>Audit-Trail:
>Unformatted:


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