Vendor import of OpenSSH.

1 files changed, 726 insertions, 0 deletions

diff --git a/crypto/openssh/ssh.h b/crypto/openssh/ssh.h
new file mode 100644
index 0000000..47872ce
--- /dev/null
+++ b/crypto/openssh/ssh.h
@@ -0,0 +1,726 @@
+/*
+ * 
+ * ssh.h
+ * 
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * 
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * 
+ * Created: Fri Mar 17 17:09:37 1995 ylo
+ * 
+ * Generic header file for ssh.
+ * 
+ */
+
+/* RCSID("$Id: ssh.h,v 1.33 2000/02/01 22:32:53 d Exp $"); */
+
+#ifndef SSH_H
+#define SSH_H
+
+#include "rsa.h"
+#include "cipher.h"
+
+/*
+ * The default cipher used if IDEA is not supported by the remote host. It is
+ * recommended that this be one of the mandatory ciphers (DES, 3DES), though
+ * that is not required.
+ */
+#define SSH_FALLBACK_CIPHER	SSH_CIPHER_3DES
+
+/* 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.
+ */
+#define PROTOCOL_MAJOR		1
+
+/*
+ * Minor protocol version.  Different version indicates minor incompatibility
+ * that does not prevent interoperation.
+ */
+#define PROTOCOL_MINOR		5
+
+/*
+ * Name for the service.  The port named by this service overrides the
+ * default port if present.
+ */
+#define SSH_SERVICE_NAME	"ssh"
+
+#define ETCDIR			"/etc"
+#define PIDDIR			"/var/run"
+
+/*
+ * System-wide file containing host keys of known hosts.  This file should be
+ * world-readable.
+ */
+#define SSH_SYSTEM_HOSTFILE	ETCDIR "/ssh_known_hosts"
+
+/*
+ * 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 SSH_PROGRAM		"/usr/bin/ssh"
+
+/*
+ * 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"
+
+/*
+ * 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"
+
+/*
+ * 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"
+
+/*
+ * 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"
+
+/*
+ * 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
+ */
+#define SSH_ASKPASS_DEFAULT	"/usr/X11R6/bin/ssh-askpass"
+#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(int 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(int 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,
+    BIGNUM * client_host_key_e, BIGNUM * client_host_key_n);
+
+/*
+ * 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);
+
+
+/*
+ * Tries to match the host name (which must be in all lowercase) against the
+ * comma-separated sequence of subpatterns (each possibly preceded by ! to
+ * indicate negation).  Returns true if there is a positive match; zero
+ * otherwise.
+ */
+int     match_hostname(const char *host, const char *pattern, unsigned int len);
+
+/*
+ * Checks whether the given host is already in the list of our known hosts.
+ * Returns HOST_OK if the host is known and has the specified key, HOST_NEW
+ * if the host is not known, and HOST_CHANGED if the host is known but used
+ * to have a different host key.  The host must be in all lowercase.
+ */
+typedef enum {
+	HOST_OK, HOST_NEW, HOST_CHANGED
+}       HostStatus;
+HostStatus 
+check_host_in_hostfile(const char *filename, const char *host,
+    BIGNUM * e, BIGNUM * n, BIGNUM * ke, BIGNUM * kn);
+
+/*
+ * Appends an entry to the host file.  Returns false if the entry could not
+ * be appended.
+ */
+int 
+add_host_to_hostfile(const char *filename, const char *host,
+    BIGNUM * e, BIGNUM * n);
+
+/*
+ * 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(BIGNUM * e, BIGNUM * n);
+
+/*
+ * 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(const char *prompt, int from_stdin);
+
+/*
+ * Saves the authentication (private) key in a file, encrypting it with
+ * passphrase.  The identification of the file (lowest 64 bits of n) will
+ * precede the key to provide identification of the key without needing a
+ * passphrase.
+ */
+int 
+save_private_key(const char *filename, const char *passphrase,
+    RSA * private_key, const char *comment);
+
+/*
+ * Loads the public part of the key file (public key and comment). Returns 0
+ * if an error occurred; zero if the public key was successfully read.  The
+ * comment of the key is returned in comment_return if it is non-NULL; the
+ * caller must free the value with xfree.
+ */
+int 
+load_public_key(const char *filename, RSA * pub,
+    char **comment_return);
+
+/*
+ * Loads the private key from the file.  Returns 0 if an error is encountered
+ * (file does not exist or is not readable, or passphrase is bad). This
+ * initializes the private key.  The comment of the key is returned in
+ * comment_return if it is non-NULL; the caller must free the value with
+ * xfree.
+ */
+int 
+load_private_key(const char *filename, const char *passphrase,
+    RSA * private_key, char **comment_return);
+
+/*------------ Definitions for logging. -----------------------*/
+
+/* Supported syslog facilities and levels. */
+typedef enum {
+	SYSLOG_FACILITY_DAEMON,
+	SYSLOG_FACILITY_USER,
+	SYSLOG_FACILITY_AUTH,
+	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_DEBUG
+}       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)));
+
+/* 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);
+
+/*---------------- definitions for channels ------------------*/
+
+/* Sets specific protocol options. */
+void    channel_set_options(int hostname_in_open);
+
+/*
+ * Allocate a new channel object and set its type and socket.  Remote_name
+ * must have been allocated with xmalloc; this will free it when the channel
+ * is freed.
+ */
+int     channel_allocate(int type, int sock, char *remote_name);
+
+/* Free the channel and close its socket. */
+void    channel_free(int channel);
+
+/* Add any bits relevant to channels in select bitmasks. */
+void    channel_prepare_select(fd_set * readset, fd_set * writeset);
+
+/*
+ * After select, perform any appropriate operations for channels which have
+ * events pending.
+ */
+void    channel_after_select(fd_set * readset, fd_set * writeset);
+
+/* If there is data to send to the connection, send some of it now. */
+void    channel_output_poll(void);
+
+/*
+ * This is called when a packet of type CHANNEL_DATA has just been received.
+ * The message type has already been consumed, but channel number and data is
+ * still there.
+ */
+void    channel_input_data(int payload_len);
+
+/* Returns true if no channel has too much buffered data. */
+int     channel_not_very_much_buffered_data(void);
+
+/* This is called after receiving CHANNEL_CLOSE. */
+void    channel_input_close(void);
+
+/* This is called after receiving CHANNEL_CLOSE_CONFIRMATION. */
+void    channel_input_close_confirmation(void);
+
+/* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
+void    channel_input_open_confirmation(void);
+
+/* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
+void    channel_input_open_failure(void);
+
+/* This closes any sockets that are listening for connections; this removes
+   any unix domain sockets. */
+void    channel_stop_listening(void);
+
+/*
+ * Closes the sockets of all channels.  This is used to close extra file
+ * descriptors after a fork.
+ */
+void    channel_close_all(void);
+
+/* Returns the maximum file descriptor number used by the channels. */
+int     channel_max_fd(void);
+
+/* Returns true if there is still an open channel over the connection. */
+int     channel_still_open(void);
+
+/*
+ * Returns a string containing a list of all open channels.  The list is
+ * suitable for displaying to the user.  It uses crlf instead of newlines.
+ * The caller should free the string with xfree.
+ */
+char   *channel_open_message(void);
+
+/*
+ * Initiate forwarding of connections to local port "port" through the secure
+ * channel to host:port from remote side.  This never returns if there was an
+ * error.
+ */
+void 
+channel_request_local_forwarding(u_short port, const char *host,
+    u_short remote_port, int gateway_ports);
+
+/*
+ * Initiate forwarding of connections to port "port" on remote host through
+ * the secure channel to host:port from local side.  This never returns if
+ * there was an error.  This registers that open requests for that port are
+ * permitted.
+ */
+void 
+channel_request_remote_forwarding(u_short port, const char *host,
+    u_short remote_port);
+
+/*
+ * Permits opening to any host/port in SSH_MSG_PORT_OPEN.  This is usually
+ * called by the server, because the user could connect to any port anyway,
+ * and the server has no way to know but to trust the client anyway.
+ */
+void    channel_permit_all_opens(void);
+
+/*
+ * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
+ * listening for the port, and sends back a success reply (or disconnect
+ * message if there was an error).  This never returns if there was an error.
+ */
+void    channel_input_port_forward_request(int is_root);
+
+/*
+ * This is called after receiving PORT_OPEN message.  This attempts to
+ * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION
+ * or CHANNEL_OPEN_FAILURE.
+ */
+void    channel_input_port_open(int payload_len);
+
+/*
+ * Creates a port for X11 connections, and starts listening for it. Returns
+ * the display name, or NULL if an error was encountered.
+ */
+char   *x11_create_display(int screen);
+
+/*
+ * Creates an internet domain socket for listening for X11 connections.
+ * Returns a suitable value for the DISPLAY variable, or NULL if an error
+ * occurs.
+ */
+char   *x11_create_display_inet(int screen, int x11_display_offset);
+
+/*
+ * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
+ * the remote channel number.  We should do whatever we want, and respond
+ * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
+ */
+void    x11_input_open(int payload_len);
+
+/*
+ * Requests forwarding of X11 connections.  This should be called on the
+ * client only.
+ */
+void    x11_request_forwarding(void);
+
+/*
+ * Requests forwarding for X11 connections, with authentication spoofing.
+ * This should be called in the client only.
+ */
+void    x11_request_forwarding_with_spoofing(const char *proto, const char *data);
+
+/* Sends a message to the server to request authentication fd forwarding. */
+void    auth_request_forwarding(void);
+
+/*
+ * Returns the name of the forwarded authentication socket.  Returns NULL if
+ * there is no forwarded authentication socket.  The returned value points to
+ * a static buffer.
+ */
+char   *auth_get_socket_name(void);
+
+/*
+ * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
+ * This starts forwarding authentication requests.
+ */
+void    auth_input_request_forwarding(struct passwd * pw);
+
+/* This is called to process an SSH_SMSG_AGENT_OPEN message. */
+void    auth_input_open_request(void);
+
+/*
+ * Returns true if the given string matches the pattern (which may contain ?
+ * and * as wildcards), and zero if it does not match.
+ */
+int     match_pattern(const char *s, const char *pattern);
+
+/*
+ * 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);
+
+/*
+ * 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(int pid, int fdin, int fdout, int fderr);
+
+/* Client side main loop for the interactive session. */
+int     client_loop(int have_pty, int escape_char);
+
+/* 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);
+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 */