Provided by: python-twisted-core_17.9.0-2ubuntu0.3_all 
NAME
conch — Conch SSH client
SYNOPSIS
conch [-AaCfINnrsTtVvx] [-c cipher_spec] [-e escape_char] [-i identity_file] [-K connection_spec]
[-L port:host:hostport] [-l user] [-m mac_spec] [-o openssh_option] [-p port] [-R port:host:hostport]
[user@] hostname [command]
DESCRIPTION
conch is a SSHv2 client for logging into a remote machine and executing commands. It provides encrypted
and secure communications across a possibly insecure network. Arbitrary TCP/IP ports can also be forwarded
over the secure connection.
conch connects and logs into hostname (as user or the current username). The user must prove her/his
identity through a public-key or a password. Alternatively, if a connection is already open to a server, a
new shell can be opened over the connection without having to reauthenticate.
If command is specified, command is executed instead of a shell. If the -s option is given, command is
treated as an SSHv2 subsystem name.
Authentication
Conch supports the public-key, keyboard-interactive, and password authentications.
The public-key method allows the RSA or DSA algorithm to be used. The client uses his/her private key,
$HOME/.ssh/id_rsa or $HOME/.ssh/id_dsa to sign the session identifier, known only by the client and server.
The server checks that the matching public key is valid for the user, and that the signature is correct.
If public-key authentication fails, conch can authenticate by sending an encrypted password over the
connection.
Connection sharing
conch has the ability to multiplex multiple shells, commands and TCP/IP ports over the same secure
connection. To disable multiplexing for a connection, use the -I flag.
The -K option determines how the client connects to the remote host. It is a comma-separated list of the
methods to use, in order of preference. The two connection methods are ‘unix’ (for connecting over a
multiplexed connection) and ‘direct’ (to connect directly). To disable connecting over a multiplexed
connection, do not include ‘unix’ in the preference list.
As an example of how connection sharing works, to speed up CVS over SSH:
conch --noshell --fork -l cvs_user cvs_host
set CVS_RSH=conch
Now, when CVS connects to cvs_host as cvs_user, instead of making a new connection to the server, conch
will add a new channel to the existing connection. This saves the cost of repeatedly negotiating the
cryptography and authentication.
The options are as follows:
-A Enables authentication agent forwarding.
-a Disables authentication agent forwarding (default).
-C Enable compression.
-c cipher_spec
Selects encryption algorithms to be used for this connection, as a comma-separated list of ciphers
in order of preference. The list that conch supports is (in order of default preference):
aes256-ctr, aes256-cbc, aes192-ctr, aes192-cbc, aes128-ctr, aes128-cbc, cast128-ctr, cast128-cbc,
blowfish-ctr, blowfish, idea-ctr, idea-cbc, 3des-ctr, 3des-cbc.
-e ch | ^ch | none
Sets the escape character for sessions with a PTY (default: ‘~’). The escape character is only
recognized at the beginning of a line (after a newline). The escape character followed by a dot
(‘.’) closes the connection; followed by ^Z suspends the connection; and followed by the escape
character sends the escape character once. Setting the character to “none” disables any escapes.
-f Fork to background after authentication.
-I Do not allow connection sharing over this connection.
-i identity_spec
The file from which the identity (private key) for RSA or DSA authentication is read. The defaults
are $HOME/.ssh/id_rsa and $HOME/.ssh/id_dsa. It is possible to use this option more than once to
use more than one private key.
-K connection_spec
Selects methods for connection to the server, as a comma-separated list of methods in order of
preference. See Connection sharing for more information.
-L port:host:hostport
Specifies that the given port on the client host is to be forwarded to the given host and port on
the remote side. This allocates a socket to listen to port on the local side, and when connections
are made to that socket, they are forwarded over the secure channel and a connection is made to
host port hostport from the remote machine. Only root can forward privieged ports.
-l user
Log in using this username.
-m mac_spec
Selects MAC (message authentication code) algorithms, as a comma-separated list in order of
preference. The list that conch supports is (in order of preference): hmac-sha2-512, hmac-
sha2-384, hmac-sha2-256, hmac-sha1, hmac-md5.
-N Do not execute a shell or command.
-n Redirect input from /dev/null.
-o openssh_option
Ignored OpenSSH options.
-p port
The port to connect to on the server.
-R port:host:hostport
Specifies that the given port on the remote host is to be forwarded to the given host and port on
the local side. This allocates a socket to listen to port on the remote side, and when connections
are made to that socket, they are forwarded over the secure channel and a connection is made to
host port hostport from the client host. Only root can forward privieged ports.
-s Reconnect to the server if the connection is lost.
-s Invoke command (mandatory) as a SSHv2 subsystem.
-T Do not allocate a TTY.
-t Allocate a TTY even if command is given.
-V Display version number only.
-v Log to stderr.
-x Disable X11 connection forwarding (default).
AUTHOR
Written by Paul Swartz <z3p@twistedmatrix.com>.
REPORTING BUGS
To report a bug, visit http://twistedmatrix.com/trac/
COPYRIGHT
Copyright © 2002-2008 Twisted Matrix Laboratories.
This is free software; see the source for copying conditions. There is NO warranty; not even for
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
ssh(1)