ssh.h - security/openssh-library - Rivoreo Source Code Repositories

 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
  *
  * Generic header file for ssh.
  *
  * As far as I am concerned, the code I have written for this software
  * can be used freely for any purpose.  Any derived versions of this
  * software must be clearly marked as such, and if the derived work is
  * incompatible with the protocol description in the RFC file, it must be
  * called by a name other than "ssh" or "Secure Shell".
  */

 /* RCSID("$OpenBSD: ssh.h,v 1.55 2000/11/25 17:19:33 markus Exp $"); */

 #ifndef SSH_H
 #define SSH_H

 #include <netinet/in.h> /* For struct sockaddr_in */
 #include <pwd.h> /* For struct pw */
 #include <stdarg.h> /* For va_list */
 #include <syslog.h> /* For LOG_AUTH and friends */
 #include <sys/socket.h> /* For struct sockaddr_storage */
 #include "fake-socket.h" /* For struct sockaddr_storage */
 #ifdef HAVE_SYS_SELECT_H
 # include <sys/select.h>
 #endif
 #include "rsa.h"
 #include "cipher.h"

 /* Cipher used for encrypting authentication files. */
 #define SSH_AUTHFILE_CIPHER	SSH_CIPHER_3DES

 /* Default port number. */
 #define SSH_DEFAULT_PORT	22

 /* Maximum number of TCP/IP ports forwarded per direction. */
 #define SSH_MAX_FORWARDS_PER_DIRECTION	100

 /*
  * Maximum number of RSA authentication identity files that can be specified
  * in configuration files or on the command line.
  */
 #define SSH_MAX_IDENTITY_FILES		100

 /*
  * Major protocol version.  Different version indicates major incompatiblity
  * that prevents communication.
  *
  * Minor protocol version.  Different version indicates minor incompatibility
  * that does not prevent interoperation.
  */
 #define PROTOCOL_MAJOR_1	1
 #define PROTOCOL_MINOR_1	5

 /* We support both SSH1 and SSH2 */
 #define PROTOCOL_MAJOR_2	2
 #define PROTOCOL_MINOR_2	0

 /*
  * Name for the service.  The port named by this service overrides the
  * default port if present.
  */
 #define SSH_SERVICE_NAME	"ssh"

 #if defined(USE_PAM) && !defined(SSHD_PAM_SERVICE)
 # define SSHD_PAM_SERVICE       "sshd"
 #endif

 #ifndef ETCDIR
 #define ETCDIR			"/etc"
 #endif /* ETCDIR */

 #ifndef PIDDIR
 #define PIDDIR			"/var/run"
 #endif /* PIDDIR */

 /*
  * System-wide file containing host keys of known hosts.  This file should be
  * world-readable.
  */
 #define SSH_SYSTEM_HOSTFILE	ETCDIR "/ssh_known_hosts"
 #define SSH_SYSTEM_HOSTFILE2	ETCDIR "/ssh_known_hosts2"

 /*
  * Of these, ssh_host_key must be readable only by root, whereas ssh_config
  * should be world-readable.
  */
 #define HOST_KEY_FILE		ETCDIR "/ssh_host_key"
 #define SERVER_CONFIG_FILE	ETCDIR "/sshd_config"
 #define HOST_CONFIG_FILE	ETCDIR "/ssh_config"
 #define HOST_DSA_KEY_FILE	ETCDIR "/ssh_host_dsa_key"
 #define DH_PRIMES		ETCDIR "/primes"

 #ifndef SSH_PROGRAM
 #define SSH_PROGRAM			"/usr/bin/ssh"
 #endif /* SSH_PROGRAM */

 #ifndef LOGIN_PROGRAM
 # ifdef LOGIN_PROGRAM_FALLBACK
 #  define LOGIN_PROGRAM		LOGIN_PROGRAM_FALLBACK
 # else
 #  define LOGIN_PROGRAM		"/usr/bin/login"
 # endif
 #endif /* LOGIN_PROGRAM */

 #ifndef ASKPASS_PROGRAM
 #define ASKPASS_PROGRAM		"/usr/lib/ssh/ssh-askpass"
 #endif /* ASKPASS_PROGRAM */

 /*
  * The process id of the daemon listening for connections is saved here to
  * make it easier to kill the correct daemon when necessary.
  */
 #define SSH_DAEMON_PID_FILE	PIDDIR "/sshd.pid"

 /*
  * The directory in user\'s home directory in which the files reside. The
  * directory should be world-readable (though not all files are).
  */
 #define SSH_USER_DIR		".ssh"

 /*
  * Relevant only when using builtin PRNG.
  */
 #ifndef SSH_PRNG_SEED_FILE
 # define SSH_PRNG_SEED_FILE      SSH_USER_DIR"/prng_seed"
 #endif /* SSH_PRNG_SEED_FILE */
 #ifndef SSH_PRNG_COMMAND_FILE
 # define SSH_PRNG_COMMAND_FILE   ETCDIR "/ssh_prng_cmds"
 #endif /* SSH_PRNG_COMMAND_FILE */

 /*
  * Per-user file containing host keys of known hosts.  This file need not be
  * readable by anyone except the user him/herself, though this does not
  * contain anything particularly secret.
  */
 #define SSH_USER_HOSTFILE	"~/.ssh/known_hosts"
 #define SSH_USER_HOSTFILE2	"~/.ssh/known_hosts2"

 /*
  * Name of the default file containing client-side authentication key. This
  * file should only be readable by the user him/herself.
  */
 #define SSH_CLIENT_IDENTITY	".ssh/identity"
 #define SSH_CLIENT_ID_DSA	".ssh/id_dsa"
 #define SSH_CLIENT_ID_RSA	".ssh/id_rsa"

 /*
  * Configuration file in user\'s home directory.  This file need not be
  * readable by anyone but the user him/herself, but does not contain anything
  * particularly secret.  If the user\'s home directory resides on an NFS
  * volume where root is mapped to nobody, this may need to be world-readable.
  */
 #define SSH_USER_CONFFILE	".ssh/config"

 /*
  * File containing a list of those rsa keys that permit logging in as this
  * user.  This file need not be readable by anyone but the user him/herself,
  * but does not contain anything particularly secret.  If the user\'s home
  * directory resides on an NFS volume where root is mapped to nobody, this
  * may need to be world-readable.  (This file is read by the daemon which is
  * running as root.)
  */
 #define SSH_USER_PERMITTED_KEYS	".ssh/authorized_keys"
 #define SSH_USER_PERMITTED_KEYS2	".ssh/authorized_keys2"

 /*
  * Per-user and system-wide ssh "rc" files.  These files are executed with
  * /bin/sh before starting the shell or command if they exist.  They will be
  * passed "proto cookie" as arguments if X11 forwarding with spoofing is in
  * use.  xauth will be run if neither of these exists.
  */
 #define SSH_USER_RC		".ssh/rc"
 #define SSH_SYSTEM_RC		ETCDIR "/sshrc"

 /*
  * Ssh-only version of /etc/hosts.equiv.  Additionally, the daemon may use
  * ~/.rhosts and /etc/hosts.equiv if rhosts authentication is enabled.
  */
 #define SSH_HOSTS_EQUIV		ETCDIR "/shosts.equiv"

 /*
  * Name of the environment variable containing the pathname of the
  * authentication socket.
  */
 #define SSH_AUTHSOCKET_ENV_NAME	"SSH_AUTH_SOCK"

 /*
  * Name of the environment variable containing the pathname of the
  * authentication socket.
  */
 #define SSH_AGENTPID_ENV_NAME	"SSH_AGENT_PID"

 /*
  * Default path to ssh-askpass used by ssh-add,
  * environment variable for overwriting the default location
  */
 #ifndef SSH_ASKPASS_DEFAULT
 # define SSH_ASKPASS_DEFAULT	"/usr/X11R6/bin/ssh-askpass"
 #endif
 #define SSH_ASKPASS_ENV		"SSH_ASKPASS"

 /*
  * Force host key length and server key length to differ by at least this
  * many bits.  This is to make double encryption with rsaref work.
  */
 #define SSH_KEY_BITS_RESERVED		128

 /*
  * Length of the session key in bytes.  (Specified as 256 bits in the
  * protocol.)
  */
 #define SSH_SESSION_KEY_LENGTH		32

 /* Name of Kerberos service for SSH to use. */
 #define KRB4_SERVICE_NAME		"rcmd"

 /*
  * Authentication methods.  New types can be added, but old types should not
  * be removed for compatibility.  The maximum allowed value is 31.
  */
 #define SSH_AUTH_RHOSTS		1
 #define SSH_AUTH_RSA		2
 #define SSH_AUTH_PASSWORD	3
 #define SSH_AUTH_RHOSTS_RSA	4
 #define SSH_AUTH_TIS		5
 #define SSH_AUTH_KERBEROS	6
 #define SSH_PASS_KERBEROS_TGT	7
 				/* 8 to 15 are reserved */
 #define SSH_PASS_AFS_TOKEN	21

 /* Protocol flags.  These are bit masks. */
 #define SSH_PROTOFLAG_SCREEN_NUMBER	1	/* X11 forwarding includes screen */
 #define SSH_PROTOFLAG_HOST_IN_FWD_OPEN	2	/* forwarding opens contain host */

 /*
  * Definition of message types.  New values can be added, but old values
  * should not be removed or without careful consideration of the consequences
  * for compatibility.  The maximum value is 254; value 255 is reserved for
  * future extension.
  */
 /* Message name */			/* msg code */	/* arguments */
 #define SSH_MSG_NONE				0	/* no message */
 #define SSH_MSG_DISCONNECT			1	/* cause (string) */
 #define SSH_SMSG_PUBLIC_KEY			2	/* ck,msk,srvk,hostk */
 #define SSH_CMSG_SESSION_KEY			3	/* key (BIGNUM) */
 #define SSH_CMSG_USER				4	/* user (string) */
 #define SSH_CMSG_AUTH_RHOSTS			5	/* user (string) */
 #define SSH_CMSG_AUTH_RSA			6	/* modulus (BIGNUM) */
 #define SSH_SMSG_AUTH_RSA_CHALLENGE		7	/* int (BIGNUM) */
 #define SSH_CMSG_AUTH_RSA_RESPONSE		8	/* int (BIGNUM) */
 #define SSH_CMSG_AUTH_PASSWORD			9	/* pass (string) */
 #define SSH_CMSG_REQUEST_PTY		        10	/* TERM, tty modes */
 #define SSH_CMSG_WINDOW_SIZE		        11	/* row,col,xpix,ypix */
 #define SSH_CMSG_EXEC_SHELL			12	/* */
 #define SSH_CMSG_EXEC_CMD			13	/* cmd (string) */
 #define SSH_SMSG_SUCCESS			14	/* */
 #define SSH_SMSG_FAILURE			15	/* */
 #define SSH_CMSG_STDIN_DATA			16	/* data (string) */
 #define SSH_SMSG_STDOUT_DATA			17	/* data (string) */
 #define SSH_SMSG_STDERR_DATA			18	/* data (string) */
 #define SSH_CMSG_EOF				19	/* */
 #define SSH_SMSG_EXITSTATUS			20	/* status (int) */
 #define SSH_MSG_CHANNEL_OPEN_CONFIRMATION	21	/* channel (int) */
 #define SSH_MSG_CHANNEL_OPEN_FAILURE		22	/* channel (int) */
 #define SSH_MSG_CHANNEL_DATA			23	/* ch,data (int,str) */
 #define SSH_MSG_CHANNEL_CLOSE			24	/* channel (int) */
 #define SSH_MSG_CHANNEL_CLOSE_CONFIRMATION	25	/* channel (int) */
 /*      SSH_CMSG_X11_REQUEST_FORWARDING         26         OBSOLETE */
 #define SSH_SMSG_X11_OPEN			27	/* channel (int) */
 #define SSH_CMSG_PORT_FORWARD_REQUEST		28	/* p,host,hp (i,s,i) */
 #define SSH_MSG_PORT_OPEN			29	/* ch,h,p (i,s,i) */
 #define SSH_CMSG_AGENT_REQUEST_FORWARDING	30	/* */
 #define SSH_SMSG_AGENT_OPEN			31	/* port (int) */
 #define SSH_MSG_IGNORE				32	/* string */
 #define SSH_CMSG_EXIT_CONFIRMATION		33	/* */
 #define SSH_CMSG_X11_REQUEST_FORWARDING		34	/* proto,data (s,s) */
 #define SSH_CMSG_AUTH_RHOSTS_RSA		35	/* user,mod (s,mpi) */
 #define SSH_MSG_DEBUG				36	/* string */
 #define SSH_CMSG_REQUEST_COMPRESSION		37	/* level 1-9 (int) */
 #define SSH_CMSG_MAX_PACKET_SIZE		38	/* size 4k-1024k (int) */
 #define SSH_CMSG_AUTH_TIS			39	/* we use this for s/key */
 #define SSH_SMSG_AUTH_TIS_CHALLENGE		40	/* challenge (string) */
 #define SSH_CMSG_AUTH_TIS_RESPONSE		41	/* response (string) */
 #define SSH_CMSG_AUTH_KERBEROS			42	/* (KTEXT) */
 #define SSH_SMSG_AUTH_KERBEROS_RESPONSE		43	/* (KTEXT) */
 #define SSH_CMSG_HAVE_KERBEROS_TGT		44	/* credentials (s) */
 #define SSH_CMSG_HAVE_AFS_TOKEN			65	/* token (s) */

 /*------------ definitions for login.c -------------*/

 /*
  * Returns the time when the user last logged in.  Returns 0 if the
  * information is not available.  This must be called before record_login.
  * The host from which the user logged in is stored in buf.
  */
 unsigned long
 get_last_login_time(uid_t uid, const char *logname,
     char *buf, unsigned int bufsize);

 /*
  * Records that the user has logged in.  This does many things normally done
  * by login(1).
  */
 void
 record_login(pid_t pid, const char *ttyname, const char *user, uid_t uid,
     const char *host, struct sockaddr *addr);

 /*
  * Records that the user has logged out.  This does many thigs normally done
  * by login(1) or init.
  */
 void    record_logout(pid_t pid, const char *ttyname);

 /*------------ definitions for sshconnect.c ----------*/

 /*
  * Opens a TCP/IP connection to the remote server on the given host.  If port
  * is 0, the default port will be used.  If anonymous is zero, a privileged
  * port will be allocated to make the connection. This requires super-user
  * privileges if anonymous is false. Connection_attempts specifies the
  * maximum number of tries, one per second.  This returns true on success,
  * and zero on failure.  If the connection is successful, this calls
  * packet_set_connection for the connection.
  */
 int
 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
     u_short port, int connection_attempts,
     int anonymous, uid_t original_real_uid,
     const char *proxy_command);

 /*
  * Starts a dialog with the server, and authenticates the current user on the
  * server.  This does not need any extra privileges.  The basic connection to
  * the server must already have been established before this is called. If
  * login fails, this function prints an error and never returns. This
  * initializes the random state, and leaves it initialized (it will also have
  * references from the packet module).
  */

 void
 ssh_login(int host_key_valid, RSA * host_key, const char *host,
     struct sockaddr * hostaddr, uid_t original_real_uid);

 /*------------ Definitions for various authentication methods. -------*/

 /*
  * Tries to authenticate the user using the .rhosts file.  Returns true if
  * authentication succeeds.  If ignore_rhosts is non-zero, this will not
  * consider .rhosts and .shosts (/etc/hosts.equiv will still be used).
  */
 int     auth_rhosts(struct passwd * pw, const char *client_user);

 /*
  * Tries to authenticate the user using the .rhosts file and the host using
  * its host key.  Returns true if authentication succeeds.
  */
 int
 auth_rhosts_rsa(struct passwd * pw, const char *client_user, RSA* client_host_key);

 /*
  * Tries to authenticate the user using password.  Returns true if
  * authentication succeeds.
  */
 int     auth_password(struct passwd * pw, const char *password);

 /*
  * Performs the RSA authentication dialog with the client.  This returns 0 if
  * the client could not be authenticated, and 1 if authentication was
  * successful.  This may exit if there is a serious protocol violation.
  */
 int     auth_rsa(struct passwd * pw, BIGNUM * client_n);

 /*
  * Parses an RSA key (number of bits, e, n) from a string.  Moves the pointer
  * over the key.  Skips any whitespace at the beginning and at end.
  */
 int     auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n);

 /*
  * Returns the name of the machine at the other end of the socket.  The
  * returned string should be freed by the caller.
  */
 char   *get_remote_hostname(int socket);

 /*
  * Return the canonical name of the host in the other side of the current
  * connection (as returned by packet_get_connection).  The host name is
  * cached, so it is efficient to call this several times.
  */
 const char *get_canonical_hostname(void);

 /*
  * Returns the remote IP address as an ascii string.  The value need not be
  * freed by the caller.
  */
 const char *get_remote_ipaddr(void);

 /* Returns the port number of the peer of the socket. */
 int     get_peer_port(int sock);

 /* Returns the port number of the remote/local host. */
 int     get_remote_port(void);
 int	get_local_port(void);


 /*
  * Performs the RSA authentication challenge-response dialog with the client,
  * and returns true (non-zero) if the client gave the correct answer to our
  * challenge; returns zero if the client gives a wrong answer.
  */
 int     auth_rsa_challenge_dialog(RSA *pk);

 /*
  * Reads a passphrase from /dev/tty with echo turned off.  Returns the
  * passphrase (allocated with xmalloc).  Exits if EOF is encountered. If
  * from_stdin is true, the passphrase will be read from stdin instead.
  */
 char   *read_passphrase(char *prompt, int from_stdin);


 /*------------ Definitions for logging. -----------------------*/

 /* Supported syslog facilities and levels. */
 typedef enum {
 	SYSLOG_FACILITY_DAEMON,
 	SYSLOG_FACILITY_USER,
 	SYSLOG_FACILITY_AUTH,
 #ifdef LOG_AUTHPRIV
 	SYSLOG_FACILITY_AUTHPRIV,
 #endif
 	SYSLOG_FACILITY_LOCAL0,
 	SYSLOG_FACILITY_LOCAL1,
 	SYSLOG_FACILITY_LOCAL2,
 	SYSLOG_FACILITY_LOCAL3,
 	SYSLOG_FACILITY_LOCAL4,
 	SYSLOG_FACILITY_LOCAL5,
 	SYSLOG_FACILITY_LOCAL6,
 	SYSLOG_FACILITY_LOCAL7
 }       SyslogFacility;

 typedef enum {
 	SYSLOG_LEVEL_QUIET,
 	SYSLOG_LEVEL_FATAL,
 	SYSLOG_LEVEL_ERROR,
 	SYSLOG_LEVEL_INFO,
 	SYSLOG_LEVEL_VERBOSE,
 	SYSLOG_LEVEL_DEBUG1,
 	SYSLOG_LEVEL_DEBUG2,
 	SYSLOG_LEVEL_DEBUG3
 }       LogLevel;
 /* Initializes logging. */
 void    log_init(char *av0, LogLevel level, SyslogFacility facility, int on_stderr);

 /* Logging implementation, depending on server or client */
 void    do_log(LogLevel level, const char *fmt, va_list args);

 /* name to facility/level */
 SyslogFacility log_facility_number(char *name);
 LogLevel log_level_number(char *name);

 /* Output a message to syslog or stderr */
 void    fatal(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void    error(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void    log(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void    verbose(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void    debug(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void    debug2(const char *fmt,...) __attribute__((format(printf, 1, 2)));
 void    debug3(const char *fmt,...) __attribute__((format(printf, 1, 2)));

 /* same as fatal() but w/o logging */
 void    fatal_cleanup(void);

 /*
  * Registers a cleanup function to be called by fatal()/fatal_cleanup()
  * before exiting. It is permissible to call fatal_remove_cleanup for the
  * function itself from the function.
  */
 void    fatal_add_cleanup(void (*proc) (void *context), void *context);

 /* Removes a cleanup function to be called at fatal(). */
 void    fatal_remove_cleanup(void (*proc) (void *context), void *context);

 /* ---- misc */

 /*
  * Expands tildes in the file name.  Returns data allocated by xmalloc.
  * Warning: this calls getpw*.
  */
 char   *tilde_expand_filename(const char *filename, uid_t my_uid);

 /* remove newline at end of string */
 char	*chop(char *s);

 /* return next token in configuration line */
 char	*strdelim(char **s);

 /* set filedescriptor to non-blocking */
 void	set_nonblock(int fd);

 /*
  * Performs the interactive session.  This handles data transmission between
  * the client and the program.  Note that the notion of stdin, stdout, and
  * stderr in this function is sort of reversed: this function writes to stdin
  * (of the child program), and reads from stdout and stderr (of the child
  * program).
  */
 void    server_loop(pid_t pid, int fdin, int fdout, int fderr);
 void    server_loop2(void);

 /* Client side main loop for the interactive session. */
 int     client_loop(int have_pty, int escape_char, int id);

 /* Linked list of custom environment strings (see auth-rsa.c). */
 struct envstring {
 	struct envstring *next;
 	char   *s;
 };

 /*
  * Ensure all of data on socket comes through. f==read || f==write
  */
 ssize_t	atomicio(ssize_t (*f)(), int fd, void *s, size_t n);

 #ifdef KRB4
 #include <krb.h>
 /*
  * Performs Kerberos v4 mutual authentication with the client. This returns 0
  * if the client could not be authenticated, and 1 if authentication was
  * successful.  This may exit if there is a serious protocol violation.
  */
 int     auth_krb4(const char *server_user, KTEXT auth, char **client);
 int     krb4_init(uid_t uid);
 void    krb4_cleanup_proc(void *ignore);
 int	auth_krb4_password(struct passwd * pw, const char *password);

 #ifdef AFS
 #include <kafs.h>

 /* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */
 int     auth_kerberos_tgt(struct passwd * pw, const char *string);
 int     auth_afs_token(struct passwd * pw, const char *token_string);

 int     creds_to_radix(CREDENTIALS * creds, unsigned char *buf, size_t buflen);
 int     radix_to_creds(const char *buf, CREDENTIALS * creds);
 #endif				/* AFS */

 #endif				/* KRB4 */

 #ifdef SKEY
 #include <skey.h>
 char   *skey_fake_keyinfo(char *username);
 int	auth_skey_password(struct passwd * pw, const char *password);
 #endif				/* SKEY */

 /* AF_UNSPEC or AF_INET or AF_INET6 */
 extern int IPv4or6;

 #endif				/* SSH_H */
	/*
	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	* All rights reserved
	*
	* Generic header file for ssh.
	*
	* As far as I am concerned, the code I have written for this software
	* can be used freely for any purpose. Any derived versions of this
	* software must be clearly marked as such, and if the derived work is
	* incompatible with the protocol description in the RFC file, it must be
	* called by a name other than "ssh" or "Secure Shell".
	*/

	/* RCSID("$OpenBSD: ssh.h,v 1.55 2000/11/25 17:19:33 markus Exp $"); */

	#ifndef SSH_H
	#define SSH_H

	#include <netinet/in.h> /* For struct sockaddr_in */
	#include <pwd.h> /* For struct pw */
	#include <stdarg.h> /* For va_list */
	#include <syslog.h> /* For LOG_AUTH and friends */
	#include <sys/socket.h> /* For struct sockaddr_storage */
	#include "fake-socket.h" /* For struct sockaddr_storage */
	#ifdef HAVE_SYS_SELECT_H
	# include <sys/select.h>
	#endif
	#include "rsa.h"
	#include "cipher.h"

	/* Cipher used for encrypting authentication files. */
	#define SSH_AUTHFILE_CIPHER SSH_CIPHER_3DES

	/* Default port number. */
	#define SSH_DEFAULT_PORT 22

	/* Maximum number of TCP/IP ports forwarded per direction. */
	#define SSH_MAX_FORWARDS_PER_DIRECTION 100

	/*
	* Maximum number of RSA authentication identity files that can be specified
	* in configuration files or on the command line.
	*/
	#define SSH_MAX_IDENTITY_FILES 100

	/*
	* Major protocol version. Different version indicates major incompatiblity
	* that prevents communication.
	*
	* Minor protocol version. Different version indicates minor incompatibility
	* that does not prevent interoperation.
	*/
	#define PROTOCOL_MAJOR_1 1
	#define PROTOCOL_MINOR_1 5

	/* We support both SSH1 and SSH2 */
	#define PROTOCOL_MAJOR_2 2
	#define PROTOCOL_MINOR_2 0

	/*
	* Name for the service. The port named by this service overrides the
	* default port if present.
	*/
	#define SSH_SERVICE_NAME "ssh"

	#if defined(USE_PAM) && !defined(SSHD_PAM_SERVICE)
	# define SSHD_PAM_SERVICE "sshd"
	#endif

	#ifndef ETCDIR
	#define ETCDIR "/etc"
	#endif /* ETCDIR */

	#ifndef PIDDIR
	#define PIDDIR "/var/run"
	#endif /* PIDDIR */

	/*
	* System-wide file containing host keys of known hosts. This file should be
	* world-readable.
	*/
	#define SSH_SYSTEM_HOSTFILE ETCDIR "/ssh_known_hosts"
	#define SSH_SYSTEM_HOSTFILE2 ETCDIR "/ssh_known_hosts2"

	/*
	* Of these, ssh_host_key must be readable only by root, whereas ssh_config
	* should be world-readable.
	*/
	#define HOST_KEY_FILE ETCDIR "/ssh_host_key"
	#define SERVER_CONFIG_FILE ETCDIR "/sshd_config"
	#define HOST_CONFIG_FILE ETCDIR "/ssh_config"
	#define HOST_DSA_KEY_FILE ETCDIR "/ssh_host_dsa_key"
	#define DH_PRIMES ETCDIR "/primes"

	#ifndef SSH_PROGRAM
	#define SSH_PROGRAM "/usr/bin/ssh"
	#endif /* SSH_PROGRAM */

	#ifndef LOGIN_PROGRAM
	# ifdef LOGIN_PROGRAM_FALLBACK
	# define LOGIN_PROGRAM LOGIN_PROGRAM_FALLBACK
	# else
	# define LOGIN_PROGRAM "/usr/bin/login"
	# endif
	#endif /* LOGIN_PROGRAM */

	#ifndef ASKPASS_PROGRAM
	#define ASKPASS_PROGRAM "/usr/lib/ssh/ssh-askpass"
	#endif /* ASKPASS_PROGRAM */

	/*
	* The process id of the daemon listening for connections is saved here to
	* make it easier to kill the correct daemon when necessary.
	*/
	#define SSH_DAEMON_PID_FILE PIDDIR "/sshd.pid"

	/*
	* The directory in user\'s home directory in which the files reside. The
	* directory should be world-readable (though not all files are).
	*/
	#define SSH_USER_DIR ".ssh"

	/*
	* Relevant only when using builtin PRNG.
	*/
	#ifndef SSH_PRNG_SEED_FILE
	# define SSH_PRNG_SEED_FILE SSH_USER_DIR"/prng_seed"
	#endif /* SSH_PRNG_SEED_FILE */
	#ifndef SSH_PRNG_COMMAND_FILE
	# define SSH_PRNG_COMMAND_FILE ETCDIR "/ssh_prng_cmds"
	#endif /* SSH_PRNG_COMMAND_FILE */

	/*
	* Per-user file containing host keys of known hosts. This file need not be
	* readable by anyone except the user him/herself, though this does not
	* contain anything particularly secret.
	*/
	#define SSH_USER_HOSTFILE "~/.ssh/known_hosts"
	#define SSH_USER_HOSTFILE2 "~/.ssh/known_hosts2"

	/*
	* Name of the default file containing client-side authentication key. This
	* file should only be readable by the user him/herself.
	*/
	#define SSH_CLIENT_IDENTITY ".ssh/identity"
	#define SSH_CLIENT_ID_DSA ".ssh/id_dsa"
	#define SSH_CLIENT_ID_RSA ".ssh/id_rsa"

	/*
	* Configuration file in user\'s home directory. This file need not be
	* readable by anyone but the user him/herself, but does not contain anything
	* particularly secret. If the user\'s home directory resides on an NFS
	* volume where root is mapped to nobody, this may need to be world-readable.
	*/
	#define SSH_USER_CONFFILE ".ssh/config"

	/*
	* File containing a list of those rsa keys that permit logging in as this
	* user. This file need not be readable by anyone but the user him/herself,
	* but does not contain anything particularly secret. If the user\'s home
	* directory resides on an NFS volume where root is mapped to nobody, this
	* may need to be world-readable. (This file is read by the daemon which is
	* running as root.)
	*/
	#define SSH_USER_PERMITTED_KEYS ".ssh/authorized_keys"
	#define SSH_USER_PERMITTED_KEYS2 ".ssh/authorized_keys2"

	/*
	* Per-user and system-wide ssh "rc" files. These files are executed with
	* /bin/sh before starting the shell or command if they exist. They will be
	* passed "proto cookie" as arguments if X11 forwarding with spoofing is in
	* use. xauth will be run if neither of these exists.
	*/
	#define SSH_USER_RC ".ssh/rc"
	#define SSH_SYSTEM_RC ETCDIR "/sshrc"

	/*
	* Ssh-only version of /etc/hosts.equiv. Additionally, the daemon may use
	* ~/.rhosts and /etc/hosts.equiv if rhosts authentication is enabled.
	*/
	#define SSH_HOSTS_EQUIV ETCDIR "/shosts.equiv"

	/*
	* Name of the environment variable containing the pathname of the
	* authentication socket.
	*/
	#define SSH_AUTHSOCKET_ENV_NAME "SSH_AUTH_SOCK"

	/*
	* Name of the environment variable containing the pathname of the
	* authentication socket.
	*/
	#define SSH_AGENTPID_ENV_NAME "SSH_AGENT_PID"

	/*
	* Default path to ssh-askpass used by ssh-add,
	* environment variable for overwriting the default location
	*/
	#ifndef SSH_ASKPASS_DEFAULT
	# define SSH_ASKPASS_DEFAULT "/usr/X11R6/bin/ssh-askpass"
	#endif
	#define SSH_ASKPASS_ENV "SSH_ASKPASS"

	/*
	* Force host key length and server key length to differ by at least this
	* many bits. This is to make double encryption with rsaref work.
	*/
	#define SSH_KEY_BITS_RESERVED 128

	/*
	* Length of the session key in bytes. (Specified as 256 bits in the
	* protocol.)
	*/
	#define SSH_SESSION_KEY_LENGTH 32

	/* Name of Kerberos service for SSH to use. */
	#define KRB4_SERVICE_NAME "rcmd"

	/*
	* Authentication methods. New types can be added, but old types should not
	* be removed for compatibility. The maximum allowed value is 31.
	*/
	#define SSH_AUTH_RHOSTS 1
	#define SSH_AUTH_RSA 2
	#define SSH_AUTH_PASSWORD 3
	#define SSH_AUTH_RHOSTS_RSA 4
	#define SSH_AUTH_TIS 5
	#define SSH_AUTH_KERBEROS 6
	#define SSH_PASS_KERBEROS_TGT 7
	/* 8 to 15 are reserved */
	#define SSH_PASS_AFS_TOKEN 21

	/* Protocol flags. These are bit masks. */
	#define SSH_PROTOFLAG_SCREEN_NUMBER 1 /* X11 forwarding includes screen */
	#define SSH_PROTOFLAG_HOST_IN_FWD_OPEN 2 /* forwarding opens contain host */

	/*
	* Definition of message types. New values can be added, but old values
	* should not be removed or without careful consideration of the consequences
	* for compatibility. The maximum value is 254; value 255 is reserved for
	* future extension.
	*/
	/* Message name / / msg code / / arguments */
	#define SSH_MSG_NONE 0 /* no message */
	#define SSH_MSG_DISCONNECT 1 /* cause (string) */
	#define SSH_SMSG_PUBLIC_KEY 2 /* ck,msk,srvk,hostk */
	#define SSH_CMSG_SESSION_KEY 3 /* key (BIGNUM) */
	#define SSH_CMSG_USER 4 /* user (string) */
	#define SSH_CMSG_AUTH_RHOSTS 5 /* user (string) */
	#define SSH_CMSG_AUTH_RSA 6 /* modulus (BIGNUM) */
	#define SSH_SMSG_AUTH_RSA_CHALLENGE 7 /* int (BIGNUM) */
	#define SSH_CMSG_AUTH_RSA_RESPONSE 8 /* int (BIGNUM) */
	#define SSH_CMSG_AUTH_PASSWORD 9 /* pass (string) */
	#define SSH_CMSG_REQUEST_PTY 10 /* TERM, tty modes */
	#define SSH_CMSG_WINDOW_SIZE 11 /* row,col,xpix,ypix */
	#define SSH_CMSG_EXEC_SHELL 12 /* */
	#define SSH_CMSG_EXEC_CMD 13 /* cmd (string) */
	#define SSH_SMSG_SUCCESS 14 /* */
	#define SSH_SMSG_FAILURE 15 /* */
	#define SSH_CMSG_STDIN_DATA 16 /* data (string) */
	#define SSH_SMSG_STDOUT_DATA 17 /* data (string) */
	#define SSH_SMSG_STDERR_DATA 18 /* data (string) */
	#define SSH_CMSG_EOF 19 /* */
	#define SSH_SMSG_EXITSTATUS 20 /* status (int) */
	#define SSH_MSG_CHANNEL_OPEN_CONFIRMATION 21 /* channel (int) */
	#define SSH_MSG_CHANNEL_OPEN_FAILURE 22 /* channel (int) */
	#define SSH_MSG_CHANNEL_DATA 23 /* ch,data (int,str) */
	#define SSH_MSG_CHANNEL_CLOSE 24 /* channel (int) */
	#define SSH_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* channel (int) */
	/* SSH_CMSG_X11_REQUEST_FORWARDING 26 OBSOLETE */
	#define SSH_SMSG_X11_OPEN 27 /* channel (int) */
	#define SSH_CMSG_PORT_FORWARD_REQUEST 28 /* p,host,hp (i,s,i) */
	#define SSH_MSG_PORT_OPEN 29 /* ch,h,p (i,s,i) */
	#define SSH_CMSG_AGENT_REQUEST_FORWARDING 30 /* */
	#define SSH_SMSG_AGENT_OPEN 31 /* port (int) */
	#define SSH_MSG_IGNORE 32 /* string */
	#define SSH_CMSG_EXIT_CONFIRMATION 33 /* */
	#define SSH_CMSG_X11_REQUEST_FORWARDING 34 /* proto,data (s,s) */
	#define SSH_CMSG_AUTH_RHOSTS_RSA 35 /* user,mod (s,mpi) */
	#define SSH_MSG_DEBUG 36 /* string */
	#define SSH_CMSG_REQUEST_COMPRESSION 37 /* level 1-9 (int) */
	#define SSH_CMSG_MAX_PACKET_SIZE 38 /* size 4k-1024k (int) */
	#define SSH_CMSG_AUTH_TIS 39 /* we use this for s/key */
	#define SSH_SMSG_AUTH_TIS_CHALLENGE 40 /* challenge (string) */
	#define SSH_CMSG_AUTH_TIS_RESPONSE 41 /* response (string) */
	#define SSH_CMSG_AUTH_KERBEROS 42 /* (KTEXT) */
	#define SSH_SMSG_AUTH_KERBEROS_RESPONSE 43 /* (KTEXT) */
	#define SSH_CMSG_HAVE_KERBEROS_TGT 44 /* credentials (s) */
	#define SSH_CMSG_HAVE_AFS_TOKEN 65 /* token (s) */

	/------------ definitions for login.c -------------/

	/*
	* Returns the time when the user last logged in. Returns 0 if the
	* information is not available. This must be called before record_login.
	* The host from which the user logged in is stored in buf.
	*/
	unsigned long
	get_last_login_time(uid_t uid, const char *logname,
	char *buf, unsigned int bufsize);

	/*
	* Records that the user has logged in. This does many things normally done
	* by login(1).
	*/
	void
	record_login(pid_t pid, const char ttyname, const char user, uid_t uid,
	const char host, struct sockaddr addr);

	/*
	* Records that the user has logged out. This does many thigs normally done
	* by login(1) or init.
	*/
	void record_logout(pid_t pid, const char *ttyname);

	/------------ definitions for sshconnect.c ----------/

	/*
	* Opens a TCP/IP connection to the remote server on the given host. If port
	* is 0, the default port will be used. If anonymous is zero, a privileged
	* port will be allocated to make the connection. This requires super-user
	* privileges if anonymous is false. Connection_attempts specifies the
	* maximum number of tries, one per second. This returns true on success,
	* and zero on failure. If the connection is successful, this calls
	* packet_set_connection for the connection.
	*/
	int
	ssh_connect(const char host, struct sockaddr_storage hostaddr,
	u_short port, int connection_attempts,
	int anonymous, uid_t original_real_uid,
	const char *proxy_command);

	/*
	* Starts a dialog with the server, and authenticates the current user on the
	* server. This does not need any extra privileges. The basic connection to
	* the server must already have been established before this is called. If
	* login fails, this function prints an error and never returns. This
	* initializes the random state, and leaves it initialized (it will also have
	* references from the packet module).
	*/

	void
	ssh_login(int host_key_valid, RSA * host_key, const char *host,
	struct sockaddr * hostaddr, uid_t original_real_uid);

	/------------ Definitions for various authentication methods. -------/

	/*
	* Tries to authenticate the user using the .rhosts file. Returns true if
	* authentication succeeds. If ignore_rhosts is non-zero, this will not
	* consider .rhosts and .shosts (/etc/hosts.equiv will still be used).
	*/
	int auth_rhosts(struct passwd * pw, const char *client_user);

	/*
	* Tries to authenticate the user using the .rhosts file and the host using
	* its host key. Returns true if authentication succeeds.
	*/
	int
	auth_rhosts_rsa(struct passwd * pw, const char client_user, RSA client_host_key);

	/*
	* Tries to authenticate the user using password. Returns true if
	* authentication succeeds.
	*/
	int auth_password(struct passwd * pw, const char *password);

	/*
	* Performs the RSA authentication dialog with the client. This returns 0 if
	* the client could not be authenticated, and 1 if authentication was
	* successful. This may exit if there is a serious protocol violation.
	*/
	int auth_rsa(struct passwd * pw, BIGNUM * client_n);

	/*
	* Parses an RSA key (number of bits, e, n) from a string. Moves the pointer
	* over the key. Skips any whitespace at the beginning and at end.
	*/
	int auth_rsa_read_key(char *cpp, unsigned int bitsp, BIGNUM * e, BIGNUM * n);

	/*
	* Returns the name of the machine at the other end of the socket. The
	* returned string should be freed by the caller.
	*/
	char *get_remote_hostname(int socket);

	/*
	* Return the canonical name of the host in the other side of the current
	* connection (as returned by packet_get_connection). The host name is
	* cached, so it is efficient to call this several times.
	*/
	const char *get_canonical_hostname(void);

	/*
	* Returns the remote IP address as an ascii string. The value need not be
	* freed by the caller.
	*/
	const char *get_remote_ipaddr(void);

	/* Returns the port number of the peer of the socket. */
	int get_peer_port(int sock);

	/* Returns the port number of the remote/local host. */
	int get_remote_port(void);
	int get_local_port(void);


	/*
	* Performs the RSA authentication challenge-response dialog with the client,
	* and returns true (non-zero) if the client gave the correct answer to our
	* challenge; returns zero if the client gives a wrong answer.
	*/
	int auth_rsa_challenge_dialog(RSA *pk);

	/*
	* Reads a passphrase from /dev/tty with echo turned off. Returns the
	* passphrase (allocated with xmalloc). Exits if EOF is encountered. If
	* from_stdin is true, the passphrase will be read from stdin instead.
	*/
	char read_passphrase(char prompt, int from_stdin);


	/------------ Definitions for logging. -----------------------/

	/* Supported syslog facilities and levels. */
	typedef enum {
	SYSLOG_FACILITY_DAEMON,
	SYSLOG_FACILITY_USER,
	SYSLOG_FACILITY_AUTH,
	#ifdef LOG_AUTHPRIV
	SYSLOG_FACILITY_AUTHPRIV,
	#endif
	SYSLOG_FACILITY_LOCAL0,
	SYSLOG_FACILITY_LOCAL1,
	SYSLOG_FACILITY_LOCAL2,
	SYSLOG_FACILITY_LOCAL3,
	SYSLOG_FACILITY_LOCAL4,
	SYSLOG_FACILITY_LOCAL5,
	SYSLOG_FACILITY_LOCAL6,
	SYSLOG_FACILITY_LOCAL7
	} SyslogFacility;

	typedef enum {
	SYSLOG_LEVEL_QUIET,
	SYSLOG_LEVEL_FATAL,
	SYSLOG_LEVEL_ERROR,
	SYSLOG_LEVEL_INFO,
	SYSLOG_LEVEL_VERBOSE,
	SYSLOG_LEVEL_DEBUG1,
	SYSLOG_LEVEL_DEBUG2,
	SYSLOG_LEVEL_DEBUG3
	} LogLevel;
	/* Initializes logging. */
	void log_init(char *av0, LogLevel level, SyslogFacility facility, int on_stderr);

	/* Logging implementation, depending on server or client */
	void do_log(LogLevel level, const char *fmt, va_list args);

	/* name to facility/level */
	SyslogFacility log_facility_number(char *name);
	LogLevel log_level_number(char *name);

	/* Output a message to syslog or stderr */
	void fatal(const char *fmt,...) __attribute__((format(printf, 1, 2)));
	void error(const char *fmt,...) __attribute__((format(printf, 1, 2)));
	void log(const char *fmt,...) __attribute__((format(printf, 1, 2)));
	void verbose(const char *fmt,...) __attribute__((format(printf, 1, 2)));
	void debug(const char *fmt,...) __attribute__((format(printf, 1, 2)));
	void debug2(const char *fmt,...) __attribute__((format(printf, 1, 2)));
	void debug3(const char *fmt,...) __attribute__((format(printf, 1, 2)));

	/* same as fatal() but w/o logging */
	void fatal_cleanup(void);

	/*
	* Registers a cleanup function to be called by fatal()/fatal_cleanup()
	* before exiting. It is permissible to call fatal_remove_cleanup for the
	* function itself from the function.
	*/
	void fatal_add_cleanup(void (proc) (void context), void *context);

	/* Removes a cleanup function to be called at fatal(). */
	void fatal_remove_cleanup(void (proc) (void context), void *context);

	/* ---- misc */

	/*
	* Expands tildes in the file name. Returns data allocated by xmalloc.
	* Warning: this calls getpw*.
	*/
	char tilde_expand_filename(const char filename, uid_t my_uid);

	/* remove newline at end of string */
	char chop(char s);

	/* return next token in configuration line */
	char strdelim(char *s);

	/* set filedescriptor to non-blocking */
	void set_nonblock(int fd);

	/*
	* Performs the interactive session. This handles data transmission between
	* the client and the program. Note that the notion of stdin, stdout, and
	* stderr in this function is sort of reversed: this function writes to stdin
	* (of the child program), and reads from stdout and stderr (of the child
	* program).
	*/
	void server_loop(pid_t pid, int fdin, int fdout, int fderr);
	void server_loop2(void);

	/* Client side main loop for the interactive session. */
	int client_loop(int have_pty, int escape_char, int id);

	/* Linked list of custom environment strings (see auth-rsa.c). */
	struct envstring {
	struct envstring *next;
	char *s;
	};

	/*
	* Ensure all of data on socket comes through. f==read \|\| f==write
	*/
	ssize_t atomicio(ssize_t (f)(), int fd, void s, size_t n);

	#ifdef KRB4
	#include <krb.h>
	/*
	* Performs Kerberos v4 mutual authentication with the client. This returns 0
	* if the client could not be authenticated, and 1 if authentication was
	* successful. This may exit if there is a serious protocol violation.
	*/
	int auth_krb4(const char server_user, KTEXT auth, char *client);
	int krb4_init(uid_t uid);
	void krb4_cleanup_proc(void *ignore);
	int auth_krb4_password(struct passwd * pw, const char *password);

	#ifdef AFS
	#include <kafs.h>

	/* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */
	int auth_kerberos_tgt(struct passwd * pw, const char *string);
	int auth_afs_token(struct passwd * pw, const char *token_string);

	int creds_to_radix(CREDENTIALS * creds, unsigned char *buf, size_t buflen);
	int radix_to_creds(const char buf, CREDENTIALS creds);
	#endif /* AFS */

	#endif /* KRB4 */

	#ifdef SKEY
	#include <skey.h>
	char skey_fake_keyinfo(char username);
	int auth_skey_password(struct passwd * pw, const char *password);
	#endif /* SKEY */

	/* AF_UNSPEC or AF_INET or AF_INET6 */
	extern int IPv4or6;

	#endif /* SSH_H */