Net::SSH Protocol Error

perlssh has asked for the wisdom of the Perl Monks concerning the following question:

I upgraded my SSH Server to Openssh 7.1p1 to overcome security vulnerabilities. But now my perl scripts using Net::SSH have stopped working and they give a Protocol Error as follow:

Protocol error: expected packet type 91, got 80 at /auto/share/perl/5.8.6/lib/site_perl/5.8.6/Net/SSH/Perl/Packet.pm line 222 /

Here is the complete debug trace:

: Reading configuration data /etc/ssh_config
: Allocated local port 1023.
: Connecting to 10.98.109.105, port 22.
: Remote version string: SSH-2.0-OpenSSH_7.1

: Remote protocol version 2.0, remote software version OpenSSH_7.1
: Net::SSH::Perl Version 1.42, protocol version 2.0.
: No compat match: OpenSSH_7.1
: Connection established.
: Sent key-exchange init (KEXINIT), wait response.
: Algorithms, c->s: 3des-cbc hmac-sha1 none
: Algorithms, s->c: 3des-cbc hmac-sha1 none
: Entering Diffie-Hellman Group 1 key exchange.
: Sent DH public key, waiting for reply.
: Received host key, type 'ssh-rsa'.
: Host '10.98.109.105' is known and matches the host key.
: Computing shared secret key.
: Verifying server signature.
: Send NEWKEYS.
: Waiting for NEWKEYS message.
: Enabling encryption/MAC/compression.
: Sending request for user-authentication service.
: Service accepted: ssh-userauth.
: Trying empty user-authentication request.
: Authentication methods that can continue: publickey,password,keyboar
+d-interactive.
: Next method to try is publickey.
: Next method to try is password.
: Trying password authentication.
: Login completed, opening dummy shell channel.
: channel 0: new [client-session]
: Requesting channel_open for channel 0.
Protocol error: expected packet type 91, got 80 at /auto/share/perl/5.
+8.6/lib/site_perl/5.8.6/Net/SSH/Perl/Packet.pm line 222
/
[download]

Can someone please help how to resolve this error?

Thanks!

Comment on Net::SSH Protocol Error Download Code

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Re: Net::SSH Protocol Error by atcroft (Abbot) on Oct 13, 2015 at 21:56 UTC
It is my understanding that in OpenSSH 7.x several changes regarding weak and legacy cryptography. (I ran into a similar problem upgrading OpenSSH on my home server.) Under "Potentially Incompatible Changes", this item may be to related: * Support for ssh-dss, ssh-dss-cert-* host and user keys is disabled by default at run-time. These may be re-enabled using the instructions at http://www.openssh.com/legacy.html The following links may be more informative: Using OpenSSH with legacy SSH implementations Release notes, OpenSSH 7.1 Release notes, OpenSSH 7.0 Release notes, OpenSSH 6.9 Release notes, OpenSSH 6.8 Hope that helps.	[reply]
Re: Net::SSH Protocol Error by salva (Canon) on Oct 14, 2015 at 06:10 UTC
You can try replacing Net::SSH::Perl by Net::OpenSSH::Compat::Perl which uses the OpenSSH binary client underneath resulting in a much better interoperability.	[reply]
Debugging Net::SSH Protocol Error by cmv (Chaplain) on Oct 07, 2016 at 15:24 UTC
Monks- This error has been looming for quite a while, and it has just recently hit-the-fan for me. If anybody has a solution, please speak up. I am attempting to debug, and am using this note to document my progress. Any help or suggestions is much appreciated! -Craig I am running with perl v5.8.8 built for darwin using the following: `Module id = Net::SSH::Perl CPAN_USERID SCHWIGON (Steffen Schwigon <schwigon@cpan.org>) CPAN_VERSION 2.01 CPAN_FILE S/SC/SCHWIGON/Net-SSH-Perl-2.01.tar.gz MANPAGE Net::SSH::Perl - Perl client Interface to SSH INST_FILE /opt/exp/perl/perl5.8/lib/site_perl/5.8.8/Net/SSH/Per +l.pm INST_VERSION 1.34` [download] The exact error message I get is as follows: `XS_Tk__Callback_Call error:Protocol error: expected packet type 91, go +t 80 at /opt/exp/perl/perl5.8/lib/site_perl/5.8.8/Net/SSH/Perl/Packet +.pm line 222` [download] Read more... (2 kB) Checking out Packet.pm I see line 222 in the following: `217 sub read_expect { 218 my $class = shift; 219 my($ssh, $type) = @_; 220 my $pack = $class->read($ssh); 221 if ($pack->type != $type) { 222 $ssh->fatal_disconnect(sprintf 223 "Protocol error: expected packet type %d, got %d", 224 $type, $pack->type); 225 } 226 $pack; 227 }` [download] It seems that `read_expect()` in this case is being called from here: `caller DUMP: $VAR1 = 'Net::SSH::Perl::SSH2'; $VAR2 = '/opt/exp/perl/perl5.8/lib/site_perl/5.8.8/Net/SSH/Perl/SSH2.p +m'; $VAR3 = 78;` [download] Going to SSH2.pm shows line 78 to look like this: 65 sub login { 66 my $ssh = shift; 67 $ssh->SUPER::login(@_); 68 my $suppress_shell = $_[2]; 69 $ssh->_login or $ssh->fatal_disconnect("Permission denied"); 70 71 $ssh->debug("Login completed, opening dummy shell channel."); 72 my $cmgr = $ssh->channel_mgr; 73 my $channel = $cmgr->new_channel( 74 ctype => 'session', local_window => 0, 75 local_maxpacket => 0, remote_name => 'client-session'); 76 $channel->open; 77 78 my $packet = Net::SSH::Perl::Packet->read_expect($ssh, 79 SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); 80 $cmgr->input_open_confirmation($packet); 81 82 unless ($suppress_shell) { 83 $ssh->debug("Got channel open confirmation, requesting she +ll."); 84 $channel->request("shell", 0); 85 } 86 } [download] So we are in the process of logging in, and expecting to get a SSH2_MSG_CHANNEL_OPEN_CONFIRMATION (defined as 91 in constants.pm), but instead we are getting message 80, which is not defined in any of the Net:SSH:Perl code. Google points me here to see a list of messages and see that message 80 is: `80 SSH_MSG_GLOBAL_REQUEST` [download] Okay, why the heck are we getting this message in the middle of login? More googling leads me to IETF which states: `4. Global Requests There are several kinds of requests that affect the state of the remote end globally, independent of any channels. An example is a request to start TCP/IP forwarding for a specific port. Note that both the client and server MAY send global requests at any time, an +d the receiver MUST respond appropriately.` [download] Read more... (2 kB) Huh, interesting. I didn't know about SSH global requests, but why is it making Net::SSH::Perl barf now? More googling gets me to stackoverflow which seems to have a reasonable answer: The message 80 stands for SSH_MSG_GLOBAL_REQUEST. Modern versions of OpenSSH server use this generic message for various proprietary extensions of the SSH protocol. Most clients will/should silently ignore unrecognized messages. The SSH.NET does ignore the SSH_MSG_GLOBAL_REQUEST too, but it does not expect the message until an authentication completes. Unfortunately it seems that OpenSSH sends some of these (maybe the hostkeys-prove-00@openssh.com) even before the authentication. The problem has been fixed in SSH.NET 2016.0.0-beta1. See Issue #8. So it seems that a good hack might be to get Net::SSH::Perl to simply ignore all of these global requests. Does that sound right? Any better suggestions?	[reply] [d/l] [select]
Re: Debugging Net::SSH Protocol Error by Mr. Muskrat (Canon) on Oct 07, 2016 at 19:45 UTC
Are you sure that you have version 2.01 of Net::SSH::Perl installed? Line 222 of Net::SSH::Perl::Packet is not the one you indicated.... https://metacpan.org/source/SCHWIGON/Net-SSH-Perl-2.01/lib/Net/SSH/Perl/Packet.pm#L222 It looks like you have something between versions 1.25 and 1.42.	[reply]
Re^2: Debugging Net::SSH Protocol Error by cmv (Chaplain) on Oct 11, 2016 at 11:53 UTC
Mr. Muskrat++ Thanks for the pointer. You are correct - I am not on version 2.01 as I thought. Looking at the 2.01 code, they already have a fix in place for this issue. I'm glad it was fixed! -Craig	[reply]
Working Hack for Net::SSH Protocol Error by cmv (Chaplain) on Oct 07, 2016 at 16:58 UTC
Folks- This is a quick hack that seems to be working for me. Suggestions on a better one would be welcome! Thanks -Craig Editing .../Net/SSH/Perl/Packet.pm: `217 sub read_expect { 218 my $class = shift; 219 my($ssh, $type) = @_; 220 my $pack = $class->read($ssh); 221 while($pack->type == 80) { # CMV Hack start vvvv 222 print STDERR "IGNORING GLOBAL MESSAGE..."; 223 $pack = $class->read($ssh); 224 print STDERR " NEXT MESSAGE IS: ", $pack->type, "\n"; 225 } # CMV Hack end ^^^^ 226 if ($pack->type != $type) { 227 $ssh->fatal_disconnect(sprintf 228 "Protocol error: expected packet type %d, got %d", 229 $type, $pack->type); 230 } 231 $pack; 232 }` [download]	[reply] [d/l]
Re: Net::SSH Protocol Error by klongfel (Initiate) on Feb 19, 2016 at 18:54 UTC
Hi, I have the same issue and have not been able to resolve it after looking at the OpenSSH links. Were you able to resolve this? If so how? Thanks, Kevin	[reply]