| Subject: | SSH to a cisco router: "Channel open failure: 1: reason 4:" |
Net-SSH-Perl-1.29 works well when connecting to a Linux machine, but
when connecting to a Cisco Router it fails. These are the DEBUG
messages:
$ssh = Net::SSH::Perl->new("$host", (debug => $DEBUG, protocol
=> '2,1') );
NMCPorto.rin.telecom.pt: Reading configuration
data /home/config/.ssh/config
NMCPorto.rin.telecom.pt: Reading configuration data /etc/ssh_config
NMCPorto.rin.telecom.pt: Connecting to 10.156.253.12, port 22.
NMCPorto.rin.telecom.pt: Remote protocol version 2.0, remote software
version Cisco-1.25
NMCPorto.rin.telecom.pt: Net::SSH::Perl Version 1.29, protocol version
2.0.
NMCPorto.rin.telecom.pt: No compat match: Cisco-1.25.
NMCPorto.rin.telecom.pt: Connection established.
$ssh->login($user, $pass);
NMCPorto.rin.telecom.pt: Sent key-exchange init (KEXINIT), wait
response.
NMCPorto.rin.telecom.pt: Algorithms, c->s: 3des-cbc hmac-sha1 none
NMCPorto.rin.telecom.pt: Algorithms, s->c: 3des-cbc hmac-sha1 none
NMCPorto.rin.telecom.pt: Entering Diffie-Hellman Group 1 key exchange.
NMCPorto.rin.telecom.pt: Sent DH public key, waiting for reply.
NMCPorto.rin.telecom.pt: Received host key, type 'ssh-rsa'.
NMCPorto.rin.telecom.pt: Host '10.156.253.12' is known and matches the
host key.
NMCPorto.rin.telecom.pt: Computing shared secret key.
NMCPorto.rin.telecom.pt: Verifying server signature.
NMCPorto.rin.telecom.pt: Waiting for NEWKEYS message.
NMCPorto.rin.telecom.pt: Enabling incoming encryption/MAC/compression.
NMCPorto.rin.telecom.pt: Send NEWKEYS, enable outgoing
encryption/MAC/compression.
NMCPorto.rin.telecom.pt: Sending request for user-authentication
service.
NMCPorto.rin.telecom.pt: Service accepted: ssh-userauth.
NMCPorto.rin.telecom.pt: Trying empty user-authentication request.
NMCPorto.rin.telecom.pt: Authentication methods that can continue:
password.
NMCPorto.rin.telecom.pt: Next method to try is password.
NMCPorto.rin.telecom.pt: Trying password authentication.
NMCPorto.rin.telecom.pt: Login completed, opening dummy shell channel.
NMCPorto.rin.telecom.pt: channel 0: new [client-session]
NMCPorto.rin.telecom.pt: Requesting channel_open for channel 0.
NMCPorto.rin.telecom.pt: channel 0: open confirm rwindow 1024 rmax 4096
NMCPorto.rin.telecom.pt: Got channel open confirmation, requesting
shell.
NMCPorto.rin.telecom.pt: Requesting service shell on channel 0.
($stdout, $stderr, $exit) = $ssh->cmd("show version");
NMCPorto.rin.telecom.pt: channel 1: new [client-session]
NMCPorto.rin.telecom.pt: Requesting channel_open for channel 1.
NMCPorto.rin.telecom.pt: Entering interactive session.
NMCPorto.rin.telecom.pt: Channel open failure: 1: reason 4:
... and the connection stops, and the command is not given.
This seems to have something to do with Channel Opening.
----------------------
Then I searched the web and found out a forum in which it was told to
make some changes in …/Net/SSH/Perl/SSH2.pm
- In sub login I removed the code that opens a "dummy channel"
# $ssh->debug("Login completed, opening dummy shell channel.");
# my $cmgr = $ssh->channel_mgr;
# my $channel = $cmgr->new_channel(
# ctype => 'session', local_window => 0,
# local_maxpacket => 0, remote_name => 'client-session');
# $channel->open;
#
# my $packet = Net::SSH::Perl::Packet->read_expect($ssh,
# SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
# $cmgr->input_open_confirmation($packet);
#
# unless ($suppress_shell) {
# $ssh->debug("Got channel open confirmation, requesting
shell.");
# $channel->request("shell", 0);
# }
- In sub client_loop, I changed the line:
last unless $oc > 1;
to
last unless $oc > 0;
With these changes I can now connect to the Router Cisco, but I can
only execute 1 (one) command. Here is the DEBUG:
$ssh = Net::SSH::Perl->new("$host", (debug => $DEBUG, protocol
=> '2,1') );
(...DEBUG remains the same)
$ssh->login($user, $pass);
NMCPorto.rin.telecom.pt: Sent key-exchange init (KEXINIT), wait
response.
NMCPorto.rin.telecom.pt: Algorithms, c->s: 3des-cbc hmac-sha1 none
NMCPorto.rin.telecom.pt: Algorithms, s->c: 3des-cbc hmac-sha1 none
NMCPorto.rin.telecom.pt: Entering Diffie-Hellman Group 1 key exchange.
NMCPorto.rin.telecom.pt: Sent DH public key, waiting for reply.
NMCPorto.rin.telecom.pt: Received host key, type 'ssh-rsa'.
NMCPorto.rin.telecom.pt: Host '10.156.253.12' is known and matches the
host key.
NMCPorto.rin.telecom.pt: Computing shared secret key.
NMCPorto.rin.telecom.pt: Verifying server signature.
NMCPorto.rin.telecom.pt: Waiting for NEWKEYS message.
NMCPorto.rin.telecom.pt: Enabling incoming encryption/MAC/compression.
NMCPorto.rin.telecom.pt: Send NEWKEYS, enable outgoing
encryption/MAC/compression.
NMCPorto.rin.telecom.pt: Sending request for user-authentication
service.
NMCPorto.rin.telecom.pt: Service accepted: ssh-userauth.
NMCPorto.rin.telecom.pt: Trying empty user-authentication request.
NMCPorto.rin.telecom.pt: Authentication methods that can continue:
password.
NMCPorto.rin.telecom.pt: Next method to try is password.
NMCPorto.rin.telecom.pt: Trying password authentication.
($stdout, $stderr, $exit) = $ssh->cmd("show version");
NMCPorto.rin.telecom.pt: channel 0: new [client-session]
NMCPorto.rin.telecom.pt: Requesting channel_open for channel 0.
NMCPorto.rin.telecom.pt: Entering interactive session.
NMCPorto.rin.telecom.pt: Sending command: show ver
NMCPorto.rin.telecom.pt: Requesting service exec on channel 0.
NMCPorto.rin.telecom.pt: channel 0: open confirm rwindow 1024 rmax 4096
NMCPorto.rin.telecom.pt: input_channel_request: rtype exit-status
reply 0
NMCPorto.rin.telecom.pt: channel 0: rcvd eof
NMCPorto.rin.telecom.pt: channel 0: output open -> drain
NMCPorto.rin.telecom.pt: channel 0: obuf empty
NMCPorto.rin.telecom.pt: channel 0: output drain -> closed
NMCPorto.rin.telecom.pt: channel 0: close_write
NMCPorto.rin.telecom.pt: channel 0: rcvd close
NMCPorto.rin.telecom.pt: channel 0: input open -> closed
NMCPorto.rin.telecom.pt: channel 0: close_read
NMCPorto.rin.telecom.pt: channel 0: send close
NMCPorto.rin.telecom.pt: channel 0: full closed
But now if I try executing another command, this happens:
($stdout, $stderr, $exit) = $ssh->cmd("show runn");
NMCPorto.rin.telecom.pt: channel 1: new [client-session]
NMCPorto.rin.telecom.pt: Requesting channel_open for channel 1.
... and the process suddently exits.
Even if this script is not compatible, is it possible for me to make
any changes so multiple commands to a Cisco Router can be made?
I would deeply appreciate any help you could give me!
Running in:
Linux Fedora 4 x86_64
Perl v5.8.6 built for x86_64-linux-thread-multi.
Net::SSH::Perl-1.29