search for: ssh_msg_channel_open

...forwarding in OpenSSH when trying to use dynamic ports. While it is possible to use OpenSSH to request a dynamic port and the OpenSSH sshd handles it just fine, the OpenSSH client gets confused when multiple ports are opened this way, due to the information passed in the "forwarded-tcpip" SSH_MSG_CHANNEL_OPEN message which is sent back to the client when connections are opened. To illustrate this problem, I tried the following with OpenSSH 6.2p1: ssh -vvv -R 0:localhost:80 -R 0:localhost:81 localhost In the debug output, I saw the lines: debug1: remote forward success for: listen 0, connect localhost...

...forwarding in OpenSSH when trying to use dynamic ports. While it is possible to use OpenSSH to request a dynamic port and the OpenSSH sshd handles it just fine, the OpenSSH client gets confused when multiple ports are opened this way, due to the information passed in the "forwarded-tcpip" SSH_MSG_CHANNEL_OPEN message which is sent back to the client when connections are opened. To illustrate this problem, I tried the following with OpenSSH 6.2p1: ssh -v -R 0:localhost:80 -R 0:localhost:81 localhost In the debug output, I saw the lines: debug1: remote forward success for: listen 0, connect localhost:8...

...attempted to implement support for direct-streamlocal at openssh.com channels in my own SSH implementation and found that the documentation in the OpenSSH PROTOCOL file doesn't match the implementation in OpenSSH. The PROTOCOL file describes the channel open message as: byte SSH_MSG_CHANNEL_OPEN string "direct-streamlocal at openssh.com" uint32 sender channel uint32 initial window size uint32 maximum packet size string socket path However, the implementation tacks some additional data to the end...

The full SSH_MSG_CHANNEL_DATA packet looks like this: uint32 packet length byte SSH_MSG_CHANNEL_DATA uint32 recipient channel uint32 nr data bytes byte[] data OpenSSH_6.1p1 considers that the 'maximum packet size' from SSH_MSG_CHANNEL_OPEN or SSH_MSG_CHANNEL_OPEN_CONFIRMATION impacts only the 'byte[] data' field and not the entire message (headers included). Section 5.1 from RFC 4254 (which talks about this limitation) leaves room for interpretation when it comes to the 'maximum packet size' because it "specif...

...f the protocol (which currently bypass these restrictions) and further develop the approach to cover the other 2 major messages detailed below. * SSH_MSG_GLOBAL_REQUEST {"tcpip-forward", "cancel-tcpip-forward", "direct-tcpip"} returning SSH_MSG_REQUEST_FAILURE * SSH_MSG_CHANNEL_OPEN {"session", "x11", etc...} returning SSH_OPEN_ADMINISTRATIVELY_PROHIBITED I'm also going to resolve an issue where sftp-server can't send the client the real user/group after chroot(). Eventually, I could see this code becoming a base for more user-friendly option...

When forwarding a Unix-domain socket, the remote socket path must be absolute (otherwise the forwarding fails later). However, guessing absolute path on the remote end is sometimes not straightforward, because the file system location may vary for many reasons, including the system installation, the choices of NFS mount points, or the remote user ID. To allow ssh clients to request remote socket

...-------------------------------------------------------------------------------------------------- 7.2. TCP/IP Forwarding Channels When a connection comes to a port for which remote forwarding has been requested, a channel is opened to forward the port to the other side. byte SSH_MSG_CHANNEL_OPEN string "forwarded-tcpip" uint32 sender channel uint32 initial window size uint32 maximum packet size string address that was connected uint32 port that was connected ###string originator IP address###################################...

Dear all, For my thesis, I've been working on automatic inference of state machines for SSH servers. I ran into a couple of particularities regarding OpenSSH's inferred state machine, and was hoping some of you might be interested. Maybe you can even shed some light on it. Setup: I'm using LearnLib's (Java) version of the L* learning algorithm [1] to come up with sequences of