draft-ietf-secsh-connect-16.txt   draft-ietf-secsh-connect-17.txt 
Network Working Group T. Ylonen Network Working Group T. Ylonen
Internet-Draft T. Kivinen Internet-Draft T. Kivinen
Expires: March 21, 2003 SSH Communications Security Corp Expires: January 12, 2004 SSH Communications Security Corp
M. Saarinen M. Saarinen
University of Jyvaskyla University of Jyvaskyla
T. Rinne T. Rinne
S. Lehtinen S. Lehtinen
SSH Communications Security Corp SSH Communications Security Corp
September 20, 2002 July 14, 2003
SSH Connection Protocol SSH Connection Protocol
draft-ietf-secsh-connect-16.txt draft-ietf-secsh-connect-17.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six
and may be updated, replaced, or obsoleted by other documents at any months and may be updated, replaced, or obsoleted by other
time. It is inappropriate to use Internet-Drafts as reference documents at any time. It is inappropriate to use Internet-Drafts
material or to cite them other than as "work in progress." as reference material or to cite them other than as "work in
progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on March 21, 2003. This Internet-Draft will expire on January 12, 2004.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract Abstract
SSH is a protocol for secure remote login and other secure network SSH is a protocol for secure remote login and other secure network
services over an insecure network. services over an insecure network.
This document describes the SSH Connection Protocol. It provides This document describes the SSH Connection Protocol. It provides
interactive login sessions, remote execution of commands, forwarded interactive login sessions, remote execution of commands,
TCP/IP connections, and forwarded X11 connections. All of these forwarded TCP/IP connections, and forwarded X11 connections. All
channels are multiplexed into a single encrypted tunnel. of these channels are multiplexed into a single encrypted tunnel.
The SSH Connection Protocol has been designed to run on top of the The SSH Connection Protocol has been designed to run on top of the
SSH transport layer and user authentication protocols. SSH transport layer and user authentication protocols.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Global Requests . . . . . . . . . . . . . . . . . . . . . . 3 2. Global Requests . . . . . . . . . . . . . . . . . . . . . . 3
3. Channel Mechanism . . . . . . . . . . . . . . . . . . . . . 3 3. Channel Mechanism . . . . . . . . . . . . . . . . . . . . . 3
3.1 Opening a Channel . . . . . . . . . . . . . . . . . . . . . 4 3.1 Opening a Channel . . . . . . . . . . . . . . . . . . . . . 4
3.2 Data Transfer . . . . . . . . . . . . . . . . . . . . . . . 5 3.2 Data Transfer . . . . . . . . . . . . . . . . . . . . . . . 5
3.3 Closing a Channel . . . . . . . . . . . . . . . . . . . . . 6 3.3 Closing a Channel . . . . . . . . . . . . . . . . . . . . . 6
3.4 Channel-Specific Requests . . . . . . . . . . . . . . . . . 7 3.4 Channel-Specific Requests . . . . . . . . . . . . . . . . . 7
4. Interactive Sessions . . . . . . . . . . . . . . . . . . . . 7 4. Interactive Sessions . . . . . . . . . . . . . . . . . . . . 8
4.1 Opening a Session . . . . . . . . . . . . . . . . . . . . . 8 4.1 Opening a Session . . . . . . . . . . . . . . . . . . . . . 8
4.2 Requesting a Pseudo-Terminal . . . . . . . . . . . . . . . . 8 4.2 Requesting a Pseudo-Terminal . . . . . . . . . . . . . . . . 8
4.3 X11 Forwarding . . . . . . . . . . . . . . . . . . . . . . . 8 4.3 X11 Forwarding . . . . . . . . . . . . . . . . . . . . . . . 9
4.3.1 Requesting X11 Forwarding . . . . . . . . . . . . . . . . . 8 4.3.1 Requesting X11 Forwarding . . . . . . . . . . . . . . . . . 9
4.3.2 X11 Channels . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3.2 X11 Channels . . . . . . . . . . . . . . . . . . . . . . . . 9
4.4 Environment Variable Passing . . . . . . . . . . . . . . . . 10 4.4 Environment Variable Passing . . . . . . . . . . . . . . . . 10
4.5 Starting a Shell or a Command . . . . . . . . . . . . . . . 10 4.5 Starting a Shell or a Command . . . . . . . . . . . . . . . 10
4.6 Session Data Transfer . . . . . . . . . . . . . . . . . . . 11 4.6 Session Data Transfer . . . . . . . . . . . . . . . . . . . 11
4.7 Window Dimension Change Message . . . . . . . . . . . . . . 11 4.7 Window Dimension Change Message . . . . . . . . . . . . . . 11
4.8 Local Flow Control . . . . . . . . . . . . . . . . . . . . . 11 4.8 Local Flow Control . . . . . . . . . . . . . . . . . . . . . 12
4.9 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.9 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.10 Returning Exit Status . . . . . . . . . . . . . . . . . . . 12 4.10 Returning Exit Status . . . . . . . . . . . . . . . . . . . 12
5. TCP/IP Port Forwarding . . . . . . . . . . . . . . . . . . . 13 5. TCP/IP Port Forwarding . . . . . . . . . . . . . . . . . . . 14
5.1 Requesting Port Forwarding . . . . . . . . . . . . . . . . . 13 5.1 Requesting Port Forwarding . . . . . . . . . . . . . . . . . 14
5.2 TCP/IP Forwarding Channels . . . . . . . . . . . . . . . . . 14 5.2 TCP/IP Forwarding Channels . . . . . . . . . . . . . . . . . 15
6. Encoding of Terminal Modes . . . . . . . . . . . . . . . . . 16 6. Encoding of Terminal Modes . . . . . . . . . . . . . . . . . 16
7. Summary of Message Numbers . . . . . . . . . . . . . . . . . 17 7. Summary of Message Numbers . . . . . . . . . . . . . . . . . 18
8. Security Considerations . . . . . . . . . . . . . . . . . . 18 8. Security Considerations . . . . . . . . . . . . . . . . . . 18
9. Intellectual Property . . . . . . . . . . . . . . . . . . . 19 9. Intellectual Property . . . . . . . . . . . . . . . . . . . 18
10. Additional Information . . . . . . . . . . . . . . . . . . . 19 10. Additional Information . . . . . . . . . . . . . . . . . . . 19
References . . . . . . . . . . . . . . . . . . . . . . . . . 19 References . . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 20
Full Copyright Statement . . . . . . . . . . . . . . . . . . 22 Full Copyright Statement . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
The SSH Connection Protocol has been designed to run on top of the The SSH Connection Protocol has been designed to run on top of the
SSH transport layer and user authentication protocols. It provides SSH transport layer and user authentication protocols. It
interactive login sessions, remote execution of commands, forwarded provides interactive login sessions, remote execution of commands,
TCP/IP connections, and forwarded X11 connections. The service name forwarded TCP/IP connections, and forwarded X11 connections. The
for this protocol (after user authentication) is "ssh-connection". service name for this protocol (after user authentication) is
"ssh-connection".
This document should be read only after reading the SSH architecture This document should be read only after reading the SSH
document [SSH-ARCH]. This document freely uses terminology and architecture document [SSH-ARCH]. This document freely uses
notation from the architecture document without reference or further terminology and notation from the architecture document without
explanation. reference or further explanation.
2. Global Requests 2. Global Requests
There are several kinds of requests that affect the state of the There are several kinds of requests that affect the state of the
remote end "globally", independent of any channels. An example is a remote end "globally", independent of any channels. An example is
request to start TCP/IP forwarding for a specific port. All such a request to start TCP/IP forwarding for a specific port. All
requests use the following format. such requests use the following format.
byte SSH_MSG_GLOBAL_REQUEST byte SSH_MSG_GLOBAL_REQUEST
string request name (restricted to US-ASCII) string request name (restricted to US-ASCII)
boolean want reply boolean want reply
... request-specific data follows ... request-specific data follows
Request names follow the DNS extensibility naming convention outlined Request names follow the DNS extensibility naming convention
in [SSH-ARCH]. outlined in [SSH-ARCH].
The recipient will respond to this message with The recipient will respond to this message with
SSH_MSG_REQUEST_SUCCESS or SSH_MSG_REQUEST_FAILURE if `want reply' is SSH_MSG_REQUEST_SUCCESS or SSH_MSG_REQUEST_FAILURE if `want reply'
TRUE. is TRUE.
byte SSH_MSG_REQUEST_SUCCESS byte SSH_MSG_REQUEST_SUCCESS
..... response specific data ..... response specific data
Usually the response specific data is non-existent. Usually the response specific data is non-existent.
If the recipient does not recognize or support the request, it simply If the recipient does not recognize or support the request, it
responds with SSH_MSG_REQUEST_FAILURE. simply responds with SSH_MSG_REQUEST_FAILURE.
byte SSH_MSG_REQUEST_FAILURE byte SSH_MSG_REQUEST_FAILURE
3. Channel Mechanism 3. Channel Mechanism
All terminal sessions, forwarded connections, etc. are channels. All terminal sessions, forwarded connections, etc. are channels.
Either side may open a channel. Multiple channels are multiplexed Either side may open a channel. Multiple channels are multiplexed
into a single connection. into a single connection.
Channels are identified by numbers at each end. The number referring Channels are identified by numbers at each end. The number
to a channel may be different on each side. Requests to open a referring to a channel may be different on each side. Requests to
channel contain the sender's channel number. Any other channel- open a channel contain the sender's channel number. Any other
related messages contain the recipient's channel number for the channel-related messages contain the recipient's channel number
channel. for the channel.
Channels are flow-controlled. No data may be sent to a channel until Channels are flow-controlled. No data may be sent to a channel
a message is received to indicate that window space is available. until a message is received to indicate that window space is
available.
3.1 Opening a Channel 3.1 Opening a Channel
When either side wishes to open a new channel, it allocates a local When either side wishes to open a new channel, it allocates a
number for the channel. It then sends the following message to the local number for the channel. It then sends the following message
other side, and includes the local channel number and initial window to the other side, and includes the local channel number and
size in the message. initial window size in the message.
byte SSH_MSG_CHANNEL_OPEN byte SSH_MSG_CHANNEL_OPEN
string channel type (restricted to US-ASCII) string channel type (restricted to US-ASCII)
uint32 sender channel uint32 sender channel
uint32 initial window size uint32 initial window size
uint32 maximum packet size uint32 maximum packet size
... channel type specific data follows ... channel type specific data follows
The channel type is a name as described in the SSH architecture The channel type is a name as described in the SSH architecture
document, with similar extension mechanisms. `sender channel' is a document, with similar extension mechanisms. `sender channel' is
local identifier for the channel used by the sender of this message. a local identifier for the channel used by the sender of this
`initial window size' specifies how many bytes of channel data can be message. `initial window size' specifies how many bytes of
sent to the sender of this message without adjusting the window. channel data can be sent to the sender of this message without
`Maximum packet size' specifies the maximum size of an individual adjusting the window. `Maximum packet size' specifies the maximum
data packet that can be sent to the sender (for example, one might size of an individual data packet that can be sent to the sender
want to use smaller packets for interactive connections to get better (for example, one might want to use smaller packets for
interactive response on slow links). interactive connections to get better interactive response on slow
links).
The remote side then decides whether it can open the channel, and The remote side then decides whether it can open the channel, and
responds with either responds with either
byte SSH_MSG_CHANNEL_OPEN_CONFIRMATION byte SSH_MSG_CHANNEL_OPEN_CONFIRMATION
uint32 recipient channel uint32 recipient channel
uint32 sender channel uint32 sender channel
uint32 initial window size uint32 initial window size
uint32 maximum packet size uint32 maximum packet size
... channel type specific data follows ... channel type specific data follows
where `recipient channel' is the channel number given in the original where `recipient channel' is the channel number given in the
open request, and `sender channel' is the channel number allocated by original open request, and `sender channel' is the channel number
the other side, or allocated by the other side, or
byte SSH_MSG_CHANNEL_OPEN_FAILURE byte SSH_MSG_CHANNEL_OPEN_FAILURE
uint32 recipient channel uint32 recipient channel
uint32 reason code uint32 reason code
string additional textual information (ISO-10646 UTF-8 [RFC2279]) string additional textual information (ISO-10646 UTF-8 [RFC2279])
string language tag (as defined in [RFC1766]) string language tag (as defined in [RFC1766])
If the recipient of the SSH_MSG_CHANNEL_OPEN message does not support If the recipient of the SSH_MSG_CHANNEL_OPEN message does not
the specified channel type, it simply responds with support the specified channel type, it simply responds with
SSH_MSG_CHANNEL_OPEN_FAILURE. The client MAY show the additional SSH_MSG_CHANNEL_OPEN_FAILURE. The client MAY show the additional
information to the user. If this is done, the client software should information to the user. If this is done, the client software
take the precautions discussed in [SSH-ARCH]. should take the precautions discussed in [SSH-ARCH].
The following reason codes are defined: The following reason codes are defined:
#define SSH_OPEN_ADMINISTRATIVELY_PROHIBITED 1 #define SSH_OPEN_ADMINISTRATIVELY_PROHIBITED 1
#define SSH_OPEN_CONNECT_FAILED 2 #define SSH_OPEN_CONNECT_FAILED 2
#define SSH_OPEN_UNKNOWN_CHANNEL_TYPE 3 #define SSH_OPEN_UNKNOWN_CHANNEL_TYPE 3
#define SSH_OPEN_RESOURCE_SHORTAGE 4 #define SSH_OPEN_RESOURCE_SHORTAGE 4
3.2 Data Transfer 3.2 Data Transfer
The window size specifies how many bytes the other party can send The window size specifies how many bytes the other party can send
before it must wait for the window to be adjusted. Both parties use before it must wait for the window to be adjusted. Both parties
the following message to adjust the window. use the following message to adjust the window.
byte SSH_MSG_CHANNEL_WINDOW_ADJUST byte SSH_MSG_CHANNEL_WINDOW_ADJUST
uint32 recipient channel uint32 recipient channel
uint32 bytes to add uint32 bytes to add
After receiving this message, the recipient MAY send the given number After receiving this message, the recipient MAY send the given
of bytes more than it was previously allowed to send; the window size number of bytes more than it was previously allowed to send; the
is incremented. window size is incremented.
Data transfer is done with messages of the following type. Data transfer is done with messages of the following type.
byte SSH_MSG_CHANNEL_DATA byte SSH_MSG_CHANNEL_DATA
uint32 recipient channel uint32 recipient channel
string data string data
The maximum amount of data allowed is the current window size. The The maximum amount of data allowed is the current window size.
window size is decremented by the amount of data sent. Both parties The window size is decremented by the amount of data sent. Both
MAY ignore all extra data sent after the allowed window is empty. parties MAY ignore all extra data sent after the allowed window is
empty.
Additionally, some channels can transfer several types of data. An Additionally, some channels can transfer several types of data.
example of this is stderr data from interactive sessions. Such data An example of this is stderr data from interactive sessions. Such
can be passed with SSH_MSG_CHANNEL_EXTENDED_DATA messages, where a data can be passed with SSH_MSG_CHANNEL_EXTENDED_DATA messages,
separate integer specifies the type of the data. The available types where a separate integer specifies the type of the data. The
and their interpretation depend on the type of the channel. available types and their interpretation depend on the type of the
channel.
byte SSH_MSG_CHANNEL_EXTENDED_DATA byte SSH_MSG_CHANNEL_EXTENDED_DATA
uint32 recipient_channel uint32 recipient_channel
uint32 data_type_code uint32 data_type_code
string data string data
Data sent with these messages consumes the same window as ordinary Data sent with these messages consumes the same window as ordinary
data. data.
Currently, only the following type is defined. Currently, only the following type is defined.
skipping to change at page 6, line 27 skipping to change at page 6, line 34
3.3 Closing a Channel 3.3 Closing a Channel
When a party will no longer send more data to a channel, it SHOULD When a party will no longer send more data to a channel, it SHOULD
send SSH_MSG_CHANNEL_EOF. send SSH_MSG_CHANNEL_EOF.
byte SSH_MSG_CHANNEL_EOF byte SSH_MSG_CHANNEL_EOF
uint32 recipient_channel uint32 recipient_channel
No explicit response is sent to this message; however, the No explicit response is sent to this message; however, the
application may send EOF to whatever is at the other end of the application may send EOF to whatever is at the other end of the
channel. Note that the channel remains open after this message, and channel. Note that the channel remains open after this message,
more data may still be sent in the other direction. This message and more data may still be sent in the other direction. This
does not consume window space and can be sent even if no window space message does not consume window space and can be sent even if no
is available. window space is available.
When either party wishes to terminate the channel, it sends When either party wishes to terminate the channel, it sends
SSH_MSG_CHANNEL_CLOSE. Upon receiving this message, a party MUST SSH_MSG_CHANNEL_CLOSE. Upon receiving this message, a party MUST
send back a SSH_MSG_CHANNEL_CLOSE unless it has already sent this send back a SSH_MSG_CHANNEL_CLOSE unless it has already sent this
message for the channel. The channel is considered closed for a message for the channel. The channel is considered closed for a
party when it has both sent and received SSH_MSG_CHANNEL_CLOSE, and party when it has both sent and received SSH_MSG_CHANNEL_CLOSE,
the party may then reuse the channel number. A party MAY send and the party may then reuse the channel number. A party MAY send
SSH_MSG_CHANNEL_CLOSE without having sent or received SSH_MSG_CHANNEL_CLOSE without having sent or received
SSH_MSG_CHANNEL_EOF. SSH_MSG_CHANNEL_EOF.
byte SSH_MSG_CHANNEL_CLOSE byte SSH_MSG_CHANNEL_CLOSE
uint32 recipient_channel uint32 recipient_channel
This message does not consume window space and can be sent even if no This message does not consume window space and can be sent even if
window space is available. no window space is available.
It is recommended that any data sent before this message is delivered It is recommended that any data sent before this message is
to the actual destination, if possible. delivered to the actual destination, if possible.
3.4 Channel-Specific Requests 3.4 Channel-Specific Requests
Many channel types have extensions that are specific to that Many channel types have extensions that are specific to that
particular channel type. An example is requesting a pty (pseudo particular channel type. An example is requesting a pty (pseudo
terminal) for an interactive session. terminal) for an interactive session.
All channel-specific requests use the following format. All channel-specific requests use the following format.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string request type (restricted to US-ASCII) string request type (restricted to US-ASCII)
boolean want reply boolean want reply
... type-specific data ... type-specific data
If want reply is FALSE, no response will be sent to the request. If want reply is FALSE, no response will be sent to the request.
Otherwise, the recipient responds with either SSH_MSG_CHANNEL_SUCCESS Otherwise, the recipient responds with either
or SSH_MSG_CHANNEL_FAILURE, or request-specific continuation SSH_MSG_CHANNEL_SUCCESS or SSH_MSG_CHANNEL_FAILURE, or request-
messages. If the request is not recognized or is not supported for specific continuation messages. If the request is not recognized
the channel, SSH_MSG_CHANNEL_FAILURE is returned. or is not supported for the channel, SSH_MSG_CHANNEL_FAILURE is
returned.
This message does not consume window space and can be sent even if no This message does not consume window space and can be sent even if
window space is available. Request types are local to each channel no window space is available. Request types are local to each
type. channel type.
The client is allowed to send further messages without waiting for The client is allowed to send further messages without waiting for
the response to the request. the response to the request.
request type names follow the DNS extensibility naming convention request type names follow the DNS extensibility naming convention
outlined in [SSH-ARCH] outlined in [SSH-ARCH]
byte SSH_MSG_CHANNEL_SUCCESS byte SSH_MSG_CHANNEL_SUCCESS
uint32 recipient_channel uint32 recipient_channel
byte SSH_MSG_CHANNEL_FAILURE byte SSH_MSG_CHANNEL_FAILURE
uint32 recipient_channel uint32 recipient_channel
These messages do not consume window space and can be sent even if no These messages do not consume window space and can be sent even if
window space is available. no window space is available.
4. Interactive Sessions 4. Interactive Sessions
A session is a remote execution of a program. The program may be a A session is a remote execution of a program. The program may be
shell, an application, a system command, or some built-in subsystem. a shell, an application, a system command, or some built-in
It may or may not have a tty, and may or may not involve X11 subsystem. It may or may not have a tty, and may or may not
forwarding. Multiple sessions can be active simultaneously. involve X11 forwarding. Multiple sessions can be active
simultaneously.
4.1 Opening a Session 4.1 Opening a Session
A session is started by sending the following message. A session is started by sending the following message.
byte SSH_MSG_CHANNEL_OPEN byte SSH_MSG_CHANNEL_OPEN
string "session" string "session"
uint32 sender channel uint32 sender channel
uint32 initial window size uint32 initial window size
uint32 maximum packet size uint32 maximum packet size
Client implementations SHOULD reject any session channel open Client implementations SHOULD reject any session channel open
requests to make it more difficult for a corrupt server to attack the requests to make it more difficult for a corrupt server to attack
client. the client.
4.2 Requesting a Pseudo-Terminal 4.2 Requesting a Pseudo-Terminal
A pseudo-terminal can be allocated for the session by sending the A pseudo-terminal can be allocated for the session by sending the
following message. following message.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient_channel uint32 recipient_channel
string "pty-req" string "pty-req"
boolean want_reply boolean want_reply
string TERM environment variable value (e.g., vt100) string TERM environment variable value (e.g., vt100)
uint32 terminal width, characters (e.g., 80) uint32 terminal width, characters (e.g., 80)
uint32 terminal height, rows (e.g., 24) uint32 terminal height, rows (e.g., 24)
uint32 terminal width, pixels (e.g., 640) uint32 terminal width, pixels (e.g., 640)
uint32 terminal height, pixels (e.g., 480) uint32 terminal height, pixels (e.g., 480)
string encoded terminal modes string encoded terminal modes
The encoding of terminal modes is described in Section Encoding of The encoding of terminal modes is described in Section Encoding of
Terminal Modes (Section 6). Zero dimension parameters MUST be Terminal Modes (Section 6). Zero dimension parameters MUST be
ignored. The character/row dimensions override the pixel dimensions ignored. The character/row dimensions override the pixel
(when nonzero). Pixel dimensions refer to the drawable area of the dimensions (when nonzero). Pixel dimensions refer to the drawable
window. area of the window.
The dimension parameters are only informational. The dimension parameters are only informational.
The client SHOULD ignore pty requests. The client SHOULD ignore pty requests.
4.3 X11 Forwarding 4.3 X11 Forwarding
4.3.1 Requesting X11 Forwarding 4.3.1 Requesting X11 Forwarding
X11 forwarding may be requested for a session by sending X11 forwarding may be requested for a session by sending
skipping to change at page 9, line 12 skipping to change at page 9, line 21
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "x11-req" string "x11-req"
boolean want reply boolean want reply
boolean single connection boolean single connection
string x11 authentication protocol string x11 authentication protocol
string x11 authentication cookie string x11 authentication cookie
uint32 x11 screen number uint32 x11 screen number
It is recommended that the authentication cookie that is sent be a It is recommended that the authentication cookie that is sent be a
fake, random cookie, and that the cookie is checked and replaced by fake, random cookie, and that the cookie is checked and replaced
the real cookie when a connection request is received. by the real cookie when a connection request is received.
X11 connection forwarding should stop when the session channel is X11 connection forwarding should stop when the session channel is
closed; however, already opened forwardings should not be closed; however, already opened forwardings should not be
automatically closed when the session channel is closed. automatically closed when the session channel is closed.
If `single connection' is TRUE, only a single connection should be If `single connection' is TRUE, only a single connection should be
forwarded. No more connections will be forwarded after the first, or forwarded. No more connections will be forwarded after the first,
after the session channel has been closed. or after the session channel has been closed.
The `x11 authentication protocol' is the name of the X11 The `x11 authentication protocol' is the name of the X11
authentication method used, e.g. "MIT-MAGIC-COOKIE-1". authentication method used, e.g. "MIT-MAGIC-COOKIE-1".
The x11 authentication cookie MUST be hexadecimal encoded. The x11 authentication cookie MUST be hexadecimal encoded.
X Protocol is documented in [SCHEIFLER]. X Protocol is documented in [SCHEIFLER].
4.3.2 X11 Channels 4.3.2 X11 Channels
X11 channels are opened with a channel open request. The resulting X11 channels are opened with a channel open request. The
channels are independent of the session, and closing the session resulting channels are independent of the session, and closing the
channel does not close the forwarded X11 channels. session channel does not close the forwarded X11 channels.
byte SSH_MSG_CHANNEL_OPEN byte SSH_MSG_CHANNEL_OPEN
string "x11" string "x11"
uint32 sender channel uint32 sender channel
uint32 initial window size uint32 initial window size
uint32 maximum packet size uint32 maximum packet size
string originator address (e.g. "192.168.7.38") string originator address (e.g. "192.168.7.38")
uint32 originator port uint32 originator port
The recipient should respond with
The recipient should respond with SSH_MSG_CHANNEL_OPEN_CONFIRMATION SSH_MSG_CHANNEL_OPEN_CONFIRMATION or SSH_MSG_CHANNEL_OPEN_FAILURE.
or SSH_MSG_CHANNEL_OPEN_FAILURE.
Implementations MUST reject any X11 channel open requests if they Implementations MUST reject any X11 channel open requests if they
have not requested X11 forwarding. have not requested X11 forwarding.
4.4 Environment Variable Passing 4.4 Environment Variable Passing
Environment variables may be passed to the shell/command to be Environment variables may be passed to the shell/command to be
started later. Uncontrolled setting of environment variables in a started later. Uncontrolled setting of environment variables in a
privileged process can be a security hazard. It is recommended that privileged process can be a security hazard. It is recommended
implementations either maintain a list of allowable variable names or that implementations either maintain a list of allowable variable
only set environment variables after the server process has dropped names or only set environment variables after the server process
sufficient privileges. has dropped sufficient privileges.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "env" string "env"
boolean want reply boolean want reply
string variable name string variable name
string variable value string variable value
4.5 Starting a Shell or a Command 4.5 Starting a Shell or a Command
Once the session has been set up, a program is started at the remote Once the session has been set up, a program is started at the
end. The program can be a shell, an application program or a remote end. The program can be a shell, an application program or
subsystem with a host-independent name. Only one of these requests a subsystem with a host-independent name. Only one of these
can succeed per channel. requests can succeed per channel.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "shell" string "shell"
boolean want reply boolean want reply
This message will request the user's default shell (typically defined This message will request the user's default shell (typically
in /etc/passwd in UNIX systems) to be started at the other end. defined in /etc/passwd in UNIX systems) to be started at the other
end.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "exec" string "exec"
boolean want reply boolean want reply
string command string command
This message will request the server to start the execution of the This message will request the server to start the execution of the
given command. The command string may contain a path. Normal given command. The command string may contain a path. Normal
precautions MUST be taken to prevent the execution of unauthorized precautions MUST be taken to prevent the execution of unauthorized
commands. commands.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "subsystem" string "subsystem"
boolean want reply boolean want reply
string subsystem name string subsystem name
This last form executes a predefined subsystem. It is expected that
these will include a general file transfer mechanism, and possibly
other features. Implementations may also allow configuring more such
mechanisms. As the user's shell is usually used to execute the
subsystem, it is advisable for the subsystem protocol to have a
"magic cookie" at the beginning of the protocol transaction to
distinguish it from arbitrary output generated by shell
initialization scripts etc. This spurious output from the shell may
be filtered out either at the server or at the client.
The server SHOULD not halt the execution of the protocol stack when This last form executes a predefined subsystem. It is expected
starting a shell or a program. All input and output from these that these will include a general file transfer mechanism, and
SHOULD be redirected to the channel or to the encrypted tunnel. possibly other features. Implementations may also allow
configuring more such mechanisms. As the user's shell is usually
used to execute the subsystem, it is advisable for the subsystem
protocol to have a "magic cookie" at the beginning of the protocol
transaction to distinguish it from arbitrary output generated by
shell initialization scripts etc. This spurious output from the
shell may be filtered out either at the server or at the client.
It is RECOMMENDED to request and check the reply for these messages. The server SHOULD not halt the execution of the protocol stack
The client SHOULD ignore these messages. when starting a shell or a program. All input and output from
these SHOULD be redirected to the channel or to the encrypted
tunnel.
It is RECOMMENDED to request and check the reply for these
messages. The client SHOULD ignore these messages.
Subsystem names follow the DNS extensibility naming convention Subsystem names follow the DNS extensibility naming convention
outlined in [SSH-ARCH]. outlined in [SSH-ARCH].
4.6 Session Data Transfer 4.6 Session Data Transfer
Data transfer for a session is done using SSH_MSG_CHANNEL_DATA and Data transfer for a session is done using SSH_MSG_CHANNEL_DATA and
SSH_MSG_CHANNEL_EXTENDED_DATA packets and the window mechanism. The SSH_MSG_CHANNEL_EXTENDED_DATA packets and the window mechanism.
extended data type SSH_EXTENDED_DATA_STDERR has been defined for The extended data type SSH_EXTENDED_DATA_STDERR has been defined
stderr data. for stderr data.
4.7 Window Dimension Change Message 4.7 Window Dimension Change Message
When the window (terminal) size changes on the client side, it MAY When the window (terminal) size changes on the client side, it MAY
send a message to the other side to inform it of the new dimensions. send a message to the other side to inform it of the new
dimensions.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient_channel uint32 recipient_channel
string "window-change" string "window-change"
boolean FALSE boolean FALSE
uint32 terminal width, columns uint32 terminal width, columns
uint32 terminal height, rows uint32 terminal height, rows
uint32 terminal width, pixels uint32 terminal width, pixels
uint32 terminal height, pixels uint32 terminal height, pixels
No response SHOULD be sent to this message. No response SHOULD be sent to this message.
4.8 Local Flow Control 4.8 Local Flow Control
On many systems, it is possible to determine if a pseudo-terminal is On many systems, it is possible to determine if a pseudo-terminal
using control-S/control-Q flow control. When flow control is is using control-S/control-Q flow control. When flow control is
allowed, it is often desirable to do the flow control at the client allowed, it is often desirable to do the flow control at the
end to speed up responses to user requests. This is facilitated by client end to speed up responses to user requests. This is
the following notification. Initially, the server is responsible for facilitated by the following notification. Initially, the server
flow control. (Here, again, client means the side originating the is responsible for flow control. (Here, again, client means the
session, and server means the other side.) side originating the session, and server means the other side.)
The message below is used by the server to inform the client when it The message below is used by the server to inform the client when
can or cannot perform flow control (control-S/control-Q processing). it can or cannot perform flow control (control-S/control-Q
If `client can do' is TRUE, the client is allowed to do flow control processing). If `client can do' is TRUE, the client is allowed to
using control-S and control-Q. The client MAY ignore this message. do flow control using control-S and control-Q. The client MAY
ignore this message.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "xon-xoff" string "xon-xoff"
boolean FALSE boolean FALSE
boolean client can do boolean client can do
No response is sent to this message. No response is sent to this message.
4.9 Signals 4.9 Signals
A signal can be delivered to the remote process/service using the A signal can be delivered to the remote process/service using the
following message. Some systems may not implement signals, in which following message. Some systems may not implement signals, in
case they SHOULD ignore this message. which case they SHOULD ignore this message.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "signal" string "signal"
boolean FALSE boolean FALSE
string signal name without the "SIG" prefix. string signal name without the "SIG" prefix.
Signal names will be encoded as discussed in the "exit-signal" Signal names will be encoded as discussed in the "exit-signal"
SSH_MSG_CHANNEL_REQUEST. SSH_MSG_CHANNEL_REQUEST.
4.10 Returning Exit Status 4.10 Returning Exit Status
When the command running at the other end terminates, the following When the command running at the other end terminates, the
message can be sent to return the exit status of the command. following message can be sent to return the exit status of the
Returning the status is RECOMMENDED. No acknowledgment is sent for command. Returning the status is RECOMMENDED. No acknowledgment
this message. The channel needs to be closed with is sent for this message. The channel needs to be closed with
SSH_MSG_CHANNEL_CLOSE after this message. SSH_MSG_CHANNEL_CLOSE after this message.
The client MAY ignore these messages. The client MAY ignore these messages.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient_channel uint32 recipient_channel
string "exit-status" string "exit-status"
boolean FALSE boolean FALSE
uint32 exit_status uint32 exit_status
The remote command may also terminate violently due to a signal. The remote command may also terminate violently due to a signal.
Such a condition can be indicated by the following message. A zero Such a condition can be indicated by the following message. A
exit_status usually means that the command terminated successfully. zero exit_status usually means that the command terminated
successfully.
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "exit-signal" string "exit-signal"
boolean FALSE boolean FALSE
string signal name without the "SIG" prefix. string signal name without the "SIG" prefix.
boolean core dumped boolean core dumped
string error message (ISO-10646 UTF-8) string error message (ISO-10646 UTF-8)
string language tag (as defined in [RFC1766]) string language tag (as defined in [RFC1766])
skipping to change at page 13, line 34 skipping to change at page 13, line 47
INT INT
KILL KILL
PIPE PIPE
QUIT QUIT
SEGV SEGV
TERM TERM
USR1 USR1
USR2 USR2
Additional signal names MAY be sent in the format "sig-name@xyz", Additional signal names MAY be sent in the format "sig-name@xyz",
where `sig-name' and `xyz' may be anything a particular implementor where `sig-name' and `xyz' may be anything a particular
wants (except the `@' sign). However, it is suggested that if a implementor wants (except the `@' sign). However, it is suggested
`configure' script is used, the non-standard signal names it finds be that if a `configure' script is used, the non-standard signal
encoded as "SIG@xyz.config.guess", where `SIG' is the signal name names it finds be encoded as "SIG@xyz.config.guess", where `SIG'
without the "SIG" prefix, and `xyz' be the host type, as determined is the signal name without the "SIG" prefix, and `xyz' be the host
by `config.guess'. type, as determined by `config.guess'.
The `error message' contains an additional explanation of the error The `error message' contains an additional explanation of the
message. The message may consist of multiple lines. The client error message. The message may consist of multiple lines. The
software MAY display this message to the user. If this is done, the client software MAY display this message to the user. If this is
client software should take the precautions discussed in [SSH-ARCH]. done, the client software should take the precautions discussed in
[SSH-ARCH].
5. TCP/IP Port Forwarding 5. TCP/IP Port Forwarding
5.1 Requesting Port Forwarding 5.1 Requesting Port Forwarding
A party need not explicitly request forwardings from its own end to A party need not explicitly request forwardings from its own end
the other direction. However, if it wishes that connections to a to the other direction. However, if it wishes that connections to
port on the other side be forwarded to the local side, it must a port on the other side be forwarded to the local side, it must
explicitly request this. explicitly request this.
byte SSH_MSG_GLOBAL_REQUEST byte SSH_MSG_GLOBAL_REQUEST
string "tcpip-forward" string "tcpip-forward"
boolean want reply boolean want reply
string address to bind (e.g. "0.0.0.0") string address to bind (e.g. "0.0.0.0")
uint32 port number to bind uint32 port number to bind
`Address to bind' and `port number to bind' specify the IP address `Address to bind' and `port number to bind' specify the IP address
and port to which the socket to be listened is bound. The address and port to which the socket to be listened is bound. The address
should be "0.0.0.0" if connections are allowed from anywhere. (Note should be "0.0.0.0" if connections are allowed from anywhere.
that the client can still filter connections based on information (Note that the client can still filter connections based on
passed in the open request.) information passed in the open request.)
Implementations should only allow forwarding privileged ports if the Implementations should only allow forwarding privileged ports if
user has been authenticated as a privileged user. the user has been authenticated as a privileged user.
Client implementations SHOULD reject these messages; they are Client implementations SHOULD reject these messages; they are
normally only sent by the client. normally only sent by the client.
If a client passes 0 as port number to bind and has want reply TRUE If a client passes 0 as port number to bind and has want reply
then the server allocates the next available unprivileged port number TRUE then the server allocates the next available unprivileged
and replies with the following message, otherwise there is no port number and replies with the following message, otherwise
response specific data. there is no response specific data.
byte SSH_MSG_GLOBAL_REQUEST_SUCCESS byte SSH_MSG_GLOBAL_REQUEST_SUCCESS
uint32 port that was bound on the server uint32 port that was bound on the server
A port forwarding can be cancelled with the following message. Note A port forwarding can be cancelled with the following message.
that channel open requests may be received until a reply to this Note that channel open requests may be received until a reply to
message is received. this message is received.
byte SSH_MSG_GLOBAL_REQUEST byte SSH_MSG_GLOBAL_REQUEST
string "cancel-tcpip-forward" string "cancel-tcpip-forward"
boolean want reply boolean want reply
string address_to_bind (e.g. "127.0.0.1") string address_to_bind (e.g. "127.0.0.1")
uint32 port number to bind uint32 port number to bind
Client implementations SHOULD reject these messages; they are Client implementations SHOULD reject these messages; they are
normally only sent by the client. normally only sent by the client.
5.2 TCP/IP Forwarding Channels 5.2 TCP/IP Forwarding Channels
When a connection comes to a port for which remote forwarding has 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 been requested, a channel is opened to forward the port to the
side. other side.
byte SSH_MSG_CHANNEL_OPEN byte SSH_MSG_CHANNEL_OPEN
string "forwarded-tcpip" string "forwarded-tcpip"
uint32 sender channel uint32 sender channel
uint32 initial window size uint32 initial window size
uint32 maximum packet size uint32 maximum packet size
string address that was connected string address that was connected
uint32 port that was connected uint32 port that was connected
string originator IP address string originator IP address
uint32 originator port uint32 originator port
Implementations MUST reject these messages unless they have Implementations MUST reject these messages unless they have
previously requested a remote TCP/IP port forwarding with the given previously requested a remote TCP/IP port forwarding with the
port number. given port number.
When a connection comes to a locally forwarded TCP/IP port, the When a connection comes to a locally forwarded TCP/IP port, the
following packet is sent to the other side. Note that these messages following packet is sent to the other side. Note that these
MAY be sent also for ports for which no forwarding has been messages MAY be sent also for ports for which no forwarding has
explicitly requested. The receiving side must decide whether to been explicitly requested. The receiving side must decide whether
allow the forwarding. to allow the forwarding.
byte SSH_MSG_CHANNEL_OPEN byte SSH_MSG_CHANNEL_OPEN
string "direct-tcpip" string "direct-tcpip"
uint32 sender channel uint32 sender channel
uint32 initial window size uint32 initial window size
uint32 maximum packet size uint32 maximum packet size
string host to connect string host to connect
uint32 port to connect uint32 port to connect
string originator IP address string originator IP address
uint32 originator port uint32 originator port
`Host to connect' and `port to connect' specify the TCP/IP host and `Host to connect' and `port to connect' specify the TCP/IP host
port where the recipient should connect the channel. `Host to and port where the recipient should connect the channel. `Host to
connect' may be either a domain name or a numeric IP address. connect' may be either a domain name or a numeric IP address.
`Originator IP address' is the numeric IP address of the machine `Originator IP address' is the numeric IP address of the machine
where the connection request comes from, and `originator port' is the where the connection request comes from, and `originator port' is
port on the originator host from where the connection came from. the port on the originator host from where the connection came
from.
Forwarded TCP/IP channels are independent of any sessions, and Forwarded TCP/IP channels are independent of any sessions, and
closing a session channel does not in any way imply that forwarded closing a session channel does not in any way imply that forwarded
connections should be closed. connections should be closed.
Client implementations SHOULD reject direct TCP/IP open requests for Client implementations SHOULD reject direct TCP/IP open requests
security reasons. for security reasons.
6. Encoding of Terminal Modes 6. Encoding of Terminal Modes
Terminal modes (as passed in a pty request) are encoded into a byte Terminal modes (as passed in a pty request) are encoded into a
stream. It is intended that the coding be portable across different byte stream. It is intended that the coding be portable across
environments. different environments.
The tty mode description is a stream of bytes. The stream consists The tty mode description is a stream of bytes. The stream
of opcode-argument pairs. It is terminated by opcode TTY_OP_END (0). consists of opcode-argument pairs. It is terminated by opcode
Opcodes 1 to 159 have a single uint32 argument. Opcodes 160 to 255 TTY_OP_END (0). Opcodes 1 to 159 have a single uint32 argument.
are not yet defined, and cause parsing to stop (they should only be Opcodes 160 to 255 are not yet defined, and cause parsing to stop
used after any other data). (they should only be used after any other data).
The client SHOULD put in the stream any modes it knows about, and the The client SHOULD put in the stream any modes it knows about, and
server MAY ignore any modes it does not know about. This allows some the server MAY ignore any modes it does not know about. This
degree of machine-independence, at least between systems that use a allows some degree of machine-independence, at least between
POSIX-like tty interface. The protocol can support other systems as systems that use a POSIX-like tty interface. The protocol can
well, but the client may need to fill reasonable values for a number support other systems as well, but the client may need to fill
of parameters so the server pty gets set to a reasonable mode (the reasonable values for a number of parameters so the server pty
server leaves all unspecified mode bits in their default values, and gets set to a reasonable mode (the server leaves all unspecified
only some combinations make sense). mode bits in their default values, and only some combinations make
sense).
The following opcodes have been defined. The naming of opcodes The following opcodes have been defined. The naming of opcodes
mostly follows the POSIX terminal mode flags. mostly follows the POSIX terminal mode flags.
0 TTY_OP_END Indicates end of options. 0 TTY_OP_END Indicates end of options.
1 VINTR Interrupt character; 255 if none. Similarly for the 1 VINTR Interrupt character; 255 if none. Similarly for the
other characters. Not all of these characters are other characters. Not all of these characters are
supported on all systems. supported on all systems.
2 VQUIT The quit character (sends SIGQUIT signal on POSIX 2 VQUIT The quit character (sends SIGQUIT signal on POSIX
systems). systems).
skipping to change at page 18, line 19 skipping to change at page 18, line 34
#define SSH_MSG_CHANNEL_EXTENDED_DATA 95 #define SSH_MSG_CHANNEL_EXTENDED_DATA 95
#define SSH_MSG_CHANNEL_EOF 96 #define SSH_MSG_CHANNEL_EOF 96
#define SSH_MSG_CHANNEL_CLOSE 97 #define SSH_MSG_CHANNEL_CLOSE 97
#define SSH_MSG_CHANNEL_REQUEST 98 #define SSH_MSG_CHANNEL_REQUEST 98
#define SSH_MSG_CHANNEL_SUCCESS 99 #define SSH_MSG_CHANNEL_SUCCESS 99
#define SSH_MSG_CHANNEL_FAILURE 100 #define SSH_MSG_CHANNEL_FAILURE 100
8. Security Considerations 8. Security Considerations
This protocol is assumed to run on top of a secure, authenticated This protocol is assumed to run on top of a secure, authenticated
transport. User authentication and protection against network-level transport. User authentication and protection against network-
attacks are assumed to be provided by the underlying protocols. level attacks are assumed to be provided by the underlying
protocols.
This protocol can, however, be used to execute commands on remote
machines. The protocol also permits the server to run commands on
the client. Implementations may wish to disallow this to prevent an
attacker from coming from the server machine to the client machine.
X11 forwarding provides major security improvements over normal
cookie-based X11 forwarding. The cookie never needs to be
transmitted in the clear, and traffic is encrypted and integrity-
protected. No useful authentication data will remain on the server
machine after the connection has been closed. On the other hand, in
some situations a forwarded X11 connection might be used to get
access to the local X server across security perimeters.
Port forwardings can potentially allow an intruder to cross security
perimeters such as firewalls. They do not offer anything
fundamentally new that a user could not do otherwise; however, they
make opening tunnels very easy. Implementations should allow policy
control over what can be forwarded. Administrators should be able to
deny forwardings where appropriate.
Since this protocol normally runs inside an encrypted tunnel,
firewalls will not be able to examine the traffic.
It is RECOMMENDED that implementations disable all the potentially It is RECOMMENDED that implementations disable all the potentially
dangerous features (e.g. agent forwarding, X11 forwarding, and dangerous features (e.g. agent forwarding, X11 forwarding, and
TCP/IP forwarding) if the host key has changed. TCP/IP forwarding) if the host key has changed.
Full security considerations for this protocol are provided in
Section 8 of [SSH-ARCH]
9. Intellectual Property 9. Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described
this document or the extent to which any license under such rights in this document or the extent to which any license under such
might or might not be available; neither does it represent that it rights might or might not be available; neither does it represent
has made any effort to identify any such rights. Information on the that it has made any effort to identify any such rights.
IETF's procedures with respect to rights in standards-track and Information on the IETF's procedures with respect to rights in
standards-related documentation can be found in BCP-11. Copies of standards-track and standards-related documentation can be found
claims of rights made available for publication and any assurances of in BCP-11. Copies of claims of rights made available for
licenses to be made available, or the result of an attempt made to publication and any assurances of licenses to be made available,
obtain a general license or permission for the use of such or the result of an attempt made to obtain a general license or
proprietary rights by implementers or users of this specification can permission for the use of such proprietary rights by implementers
be obtained from the IETF Secretariat. or users of this specification can be obtained from the IETF
Secretariat.
The IETF has been notified of intellectual property rights claimed in The IETF has been notified of intellectual property rights claimed
regard to some or all of the specification contained in this in regard to some or all of the specification contained in this
document. For more information consult the online list of claimed document. For more information consult the online list of claimed
rights. rights.
10. Additional Information 10. Additional Information
The current document editor is: Darren.Moffat@Sun.COM. Comments on The current document editor is: Darren.Moffat@Sun.COM. Comments
this internet draft should be sent to the IETF SECSH working group, on this internet draft should be sent to the IETF SECSH working
details at: http://ietf.org/html.charters/secsh-charter.html group, details at: http://ietf.org/html.charters/secsh-
charter.html
References References
[RFC1766] Alvestrand, H., "Tags for the Identification of [RFC1766] Alvestrand, H., "Tags for the Identification of
Languages", RFC 1766, March 1995. Languages", RFC 1766, March 1995.
[RFC1884] Hinden, R., Deering, S. and Editors, "IP Version 6 [RFC1884] Hinden, R., Deering, S. and Editors, "IP Version 6
Addressing Architecture", RFC 1884, December 1995. Addressing Architecture", RFC 1884, December 1995.
[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO [RFC2279] Yergeau, F., "UTF-8, a transformation format of
10646", RFC 2279, January 1998. ISO 10646", RFC 2279, January 1998.
[SCHEIFLER] Scheifler, R., "X Window System : The Complete [SCHEIFLER] Scheifler, R., "X Window System : The Complete
Reference to Xlib, X Protocol, Icccm, Xlfd, 3rd Reference to Xlib, X Protocol, Icccm, Xlfd, 3rd
edition.", Digital Press ISBN 1555580882, Feburary edition.", Digital Press ISBN 1555580882, Feburary
1992. 1992.
[POSIX] ISO/IEC, 9945-1., "Information technology -- Portable [POSIX] ISO/IEC, 9945-1., "Information technology --
Operating System Interface (POSIX)-Part 1: System Portable Operating System Interface (POSIX)-Part
Application Program Interface (API) C Language", 1: System Application Program Interface (API) C
ANSI/IEE Std 1003.1, July 1996. Language", ANSI/IEE Std 1003.1, July 1996.
[SSH-ARCH] Ylonen, T., "SSH Protocol Architecture", I-D draft- [SSH-ARCH] Ylonen, T., "SSH Protocol Architecture", I-D
ietf-architecture-13.txt, September 2002. draft-ietf-architecture-14.txt, July 2003.
[SSH-TRANS] Ylonen, T., "SSH Transport Layer Protocol", I-D [SSH-TRANS] Ylonen, T., "SSH Transport Layer Protocol", I-D
draft-ietf-transport-15.txt, September 2002. draft-ietf-transport-16.txt, July 2003.
[SSH-USERAUTH] Ylonen, T., "SSH Authentication Protocol", I-D draft- [SSH-USERAUTH] Ylonen, T., "SSH Authentication Protocol", I-D
ietf-userauth-16.txt, September 2002. draft-ietf-userauth-17.txt, July 2003.
[SSH-CONNECT] Ylonen, T., "SSH Connection Protocol", I-D draft- [SSH-CONNECT] Ylonen, T., "SSH Connection Protocol", I-D draft-
ietf-connect-16.txt, September 2002. ietf-connect-17.txt, July 2003.
[SSH-NUMBERS] Lehtinen, S. and D. Moffat, "SSH Protocol Assigned
Numbers", I-D draft-ietf-secsh-assignednumbers-
03.txt, July 2003.
Authors' Addresses Authors' Addresses
Tatu Ylonen Tatu Ylonen
SSH Communications Security Corp SSH Communications Security Corp
Fredrikinkatu 42 Fredrikinkatu 42
HELSINKI FIN-00100 HELSINKI FIN-00100
Finland Finland
EMail: ylo@ssh.com EMail: ylo@ssh.com
skipping to change at page 22, line 7 skipping to change at page 22, line 7
Sami Lehtinen Sami Lehtinen
SSH Communications Security Corp SSH Communications Security Corp
Fredrikinkatu 42 Fredrikinkatu 42
HELSINKI FIN-00100 HELSINKI FIN-00100
Finland Finland
EMail: sjl@ssh.com EMail: sjl@ssh.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain it to others, and derivative works that comment on or otherwise
or assist in its implementation may be prepared, copied, published explain it or assist in its implementation may be prepared,
and distributed, in whole or in part, without restriction of any copied, published and distributed, in whole or in part, without
kind, provided that the above copyright notice and this paragraph are restriction of any kind, provided that the above copyright notice
included on all such copies and derivative works. However, this and this paragraph are included on all such copies and derivative
document itself may not be modified in any way, such as by removing works. However, this document itself may not be modified in any
the copyright notice or references to the Internet Society or other way, such as by removing the copyright notice or references to the
Internet organizations, except as needed for the purpose of Internet Society or other Internet organizations, except as needed
developing Internet standards in which case the procedures for for the purpose of developing Internet standards in which case the
copyrights defined in the Internet Standards process must be procedures for copyrights defined in the Internet Standards
followed, or as required to translate it into languages other than process must be followed, or as required to translate it into
English. languages other than English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns. be revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement Acknowledgement
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/