servconf.c - security/openssh-library - Rivoreo Source Code Repositories

 /*
  *
  * servconf.c
  *
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  *
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
  *
  * Created: Mon Aug 21 15:48:58 1995 ylo
  *
  */

 #include "includes.h"
 RCSID("$Id: servconf.c,v 1.12 2000/04/16 01:18:45 damien Exp $");

 #include "ssh.h"
 #include "servconf.h"
 #include "xmalloc.h"
 #include "compat.h"

 /* add listen address */
 void add_listen_addr(ServerOptions *options, char *addr);

 /* Initializes the server options to their default values. */

 void
 initialize_server_options(ServerOptions *options)
 {
 	memset(options, 0, sizeof(*options));
 	options->num_ports = 0;
 	options->ports_from_cmdline = 0;
 	options->listen_addrs = NULL;
 	options->host_key_file = NULL;
 	options->dsa_key_file = NULL;
 	options->server_key_bits = -1;
 	options->login_grace_time = -1;
 	options->key_regeneration_time = -1;
 	options->permit_root_login = -1;
 	options->ignore_rhosts = -1;
 	options->ignore_user_known_hosts = -1;
 	options->print_motd = -1;
 	options->check_mail = -1;
 	options->x11_forwarding = -1;
 	options->x11_display_offset = -1;
 	options->strict_modes = -1;
 	options->keepalives = -1;
 	options->log_facility = (SyslogFacility) - 1;
 	options->log_level = (LogLevel) - 1;
 	options->rhosts_authentication = -1;
 	options->rhosts_rsa_authentication = -1;
 	options->rsa_authentication = -1;
 #ifdef KRB4
 	options->kerberos_authentication = -1;
 	options->kerberos_or_local_passwd = -1;
 	options->kerberos_ticket_cleanup = -1;
 #endif
 #ifdef AFS
 	options->kerberos_tgt_passing = -1;
 	options->afs_token_passing = -1;
 #endif
 	options->password_authentication = -1;
 #ifdef SKEY
 	options->skey_authentication = -1;
 #endif
 	options->permit_empty_passwd = -1;
 	options->use_login = -1;
 	options->num_allow_users = 0;
 	options->num_deny_users = 0;
 	options->num_allow_groups = 0;
 	options->num_deny_groups = 0;
 	options->ciphers = NULL;
 	options->protocol = SSH_PROTO_UNKNOWN;
 }

 void
 fill_default_server_options(ServerOptions *options)
 {
 	if (options->num_ports == 0)
 		options->ports[options->num_ports++] = SSH_DEFAULT_PORT;
 	if (options->listen_addrs == NULL)
 		add_listen_addr(options, NULL);
 	if (options->host_key_file == NULL)
 		options->host_key_file = HOST_KEY_FILE;
 	if (options->dsa_key_file == NULL)
 		options->dsa_key_file = DSA_KEY_FILE;
 	if (options->server_key_bits == -1)
 		options->server_key_bits = 768;
 	if (options->login_grace_time == -1)
 		options->login_grace_time = 600;
 	if (options->key_regeneration_time == -1)
 		options->key_regeneration_time = 3600;
 	if (options->permit_root_login == -1)
 		options->permit_root_login = 1;			/* yes */
 	if (options->ignore_rhosts == -1)
 		options->ignore_rhosts = 1;
 	if (options->ignore_user_known_hosts == -1)
 		options->ignore_user_known_hosts = 0;
 	if (options->check_mail == -1)
 		options->check_mail = 0;
 	if (options->print_motd == -1)
 		options->print_motd = 1;
 	if (options->x11_forwarding == -1)
 		options->x11_forwarding = 0;
 	if (options->x11_display_offset == -1)
 		options->x11_display_offset = 10;
 	if (options->strict_modes == -1)
 		options->strict_modes = 1;
 	if (options->keepalives == -1)
 		options->keepalives = 1;
 	if (options->log_facility == (SyslogFacility) (-1))
 		options->log_facility = SYSLOG_FACILITY_AUTH;
 	if (options->log_level == (LogLevel) (-1))
 		options->log_level = SYSLOG_LEVEL_INFO;
 	if (options->rhosts_authentication == -1)
 		options->rhosts_authentication = 0;
 	if (options->rhosts_rsa_authentication == -1)
 		options->rhosts_rsa_authentication = 0;
 	if (options->rsa_authentication == -1)
 		options->rsa_authentication = 1;
 #ifdef KRB4
 	if (options->kerberos_authentication == -1)
 		options->kerberos_authentication = (access(KEYFILE, R_OK) == 0);
 	if (options->kerberos_or_local_passwd == -1)
 		options->kerberos_or_local_passwd = 1;
 	if (options->kerberos_ticket_cleanup == -1)
 		options->kerberos_ticket_cleanup = 1;
 #endif /* KRB4 */
 #ifdef AFS
 	if (options->kerberos_tgt_passing == -1)
 		options->kerberos_tgt_passing = 0;
 	if (options->afs_token_passing == -1)
 		options->afs_token_passing = k_hasafs();
 #endif /* AFS */
 	if (options->password_authentication == -1)
 		options->password_authentication = 1;
 #ifdef SKEY
 	if (options->skey_authentication == -1)
 		options->skey_authentication = 1;
 #endif
 	if (options->permit_empty_passwd == -1)
 		options->permit_empty_passwd = 0;
 	if (options->use_login == -1)
 		options->use_login = 0;
 	if (options->protocol == SSH_PROTO_UNKNOWN)
 		options->protocol = SSH_PROTO_1;
 }

 #define WHITESPACE " \t\r\n"

 /* Keyword tokens. */
 typedef enum {
 	sBadOption,		/* == unknown option */
 	sPort, sHostKeyFile, sServerKeyBits, sLoginGraceTime, sKeyRegenerationTime,
 	sPermitRootLogin, sLogFacility, sLogLevel,
 	sRhostsAuthentication, sRhostsRSAAuthentication, sRSAAuthentication,
 #ifdef KRB4
 	sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,
 #endif
 #ifdef AFS
 	sKerberosTgtPassing, sAFSTokenPassing,
 #endif
 #ifdef SKEY
 	sSkeyAuthentication,
 #endif
 	sPasswordAuthentication, sListenAddress,
 	sPrintMotd, sIgnoreRhosts, sX11Forwarding, sX11DisplayOffset,
 	sStrictModes, sEmptyPasswd, sRandomSeedFile, sKeepAlives, sCheckMail,
 	sUseLogin, sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups,
 	sIgnoreUserKnownHosts, sDSAKeyFile, sCiphers, sProtocol
 } ServerOpCodes;

 /* Textual representation of the tokens. */
 static struct {
 	const char *name;
 	ServerOpCodes opcode;
 } keywords[] = {
 	{ "port", sPort },
 	{ "hostkey", sHostKeyFile },
 	{ "dsakey", sDSAKeyFile },
 	{ "serverkeybits", sServerKeyBits },
 	{ "logingracetime", sLoginGraceTime },
 	{ "keyregenerationinterval", sKeyRegenerationTime },
 	{ "permitrootlogin", sPermitRootLogin },
 	{ "syslogfacility", sLogFacility },
 	{ "loglevel", sLogLevel },
 	{ "rhostsauthentication", sRhostsAuthentication },
 	{ "rhostsrsaauthentication", sRhostsRSAAuthentication },
 	{ "rsaauthentication", sRSAAuthentication },
 #ifdef KRB4
 	{ "kerberosauthentication", sKerberosAuthentication },
 	{ "kerberosorlocalpasswd", sKerberosOrLocalPasswd },
 	{ "kerberosticketcleanup", sKerberosTicketCleanup },
 #endif
 #ifdef AFS
 	{ "kerberostgtpassing", sKerberosTgtPassing },
 	{ "afstokenpassing", sAFSTokenPassing },
 #endif
 	{ "passwordauthentication", sPasswordAuthentication },
 #ifdef SKEY
 	{ "skeyauthentication", sSkeyAuthentication },
 #endif
 	{ "checkmail", sCheckMail },
 	{ "listenaddress", sListenAddress },
 	{ "printmotd", sPrintMotd },
 	{ "ignorerhosts", sIgnoreRhosts },
 	{ "ignoreuserknownhosts", sIgnoreUserKnownHosts },
 	{ "x11forwarding", sX11Forwarding },
 	{ "x11displayoffset", sX11DisplayOffset },
 	{ "strictmodes", sStrictModes },
 	{ "permitemptypasswords", sEmptyPasswd },
 	{ "uselogin", sUseLogin },
 	{ "randomseed", sRandomSeedFile },
 	{ "keepalive", sKeepAlives },
 	{ "allowusers", sAllowUsers },
 	{ "denyusers", sDenyUsers },
 	{ "allowgroups", sAllowGroups },
 	{ "denygroups", sDenyGroups },
 	{ "ciphers", sCiphers },
 	{ "protocol", sProtocol },
 	{ NULL, 0 }
 };

 /*
  * Returns the number of the token pointed to by cp of length len. Never
  * returns if the token is not known.
  */

 static ServerOpCodes
 parse_token(const char *cp, const char *filename,
 	    int linenum)
 {
 	unsigned int i;

 	for (i = 0; keywords[i].name; i++)
 		if (strcasecmp(cp, keywords[i].name) == 0)
 			return keywords[i].opcode;

 	fprintf(stderr, "%s: line %d: Bad configuration option: %s\n",
 		filename, linenum, cp);
 	return sBadOption;
 }

 /*
  * add listen address
  */
 void
 add_listen_addr(ServerOptions *options, char *addr)
 {
 	extern int IPv4or6;
 	struct addrinfo hints, *ai, *aitop;
 	char strport[NI_MAXSERV];
 	int gaierr;
 	int i;

 	if (options->num_ports == 0)
 		options->ports[options->num_ports++] = SSH_DEFAULT_PORT;
 	for (i = 0; i < options->num_ports; i++) {
 		memset(&hints, 0, sizeof(hints));
 		hints.ai_family = IPv4or6;
 		hints.ai_socktype = SOCK_STREAM;
 		hints.ai_flags = (addr == NULL) ? AI_PASSIVE : 0;
 		snprintf(strport, sizeof strport, "%d", options->ports[i]);
 		if ((gaierr = getaddrinfo(addr, strport, &hints, &aitop)) != 0)
 			fatal("bad addr or host: %s (%s)\n",
 			    addr ? addr : "<NULL>",
 			    gai_strerror(gaierr));
 		for (ai = aitop; ai->ai_next; ai = ai->ai_next)
 			;
 		ai->ai_next = options->listen_addrs;
 		options->listen_addrs = aitop;
 	}
 }

 /* Reads the server configuration file. */

 void
 read_server_config(ServerOptions *options, const char *filename)
 {
 	FILE *f;
 	char line[1024];
 	char *cp, **charptr;
 	int linenum, *intptr, value;
 	int bad_options = 0;
 	ServerOpCodes opcode;

 	f = fopen(filename, "r");
 	if (!f) {
 		perror(filename);
 		exit(1);
 	}
 	linenum = 0;
 	while (fgets(line, sizeof(line), f)) {
 		linenum++;
 		cp = line + strspn(line, WHITESPACE);
 		if (!*cp || *cp == '#')
 			continue;
 		cp = strtok(cp, WHITESPACE);
 		opcode = parse_token(cp, filename, linenum);
 		switch (opcode) {
 		case sBadOption:
 			bad_options++;
 			continue;
 		case sPort:
 			/* ignore ports from configfile if cmdline specifies ports */
 			if (options->ports_from_cmdline)
 				continue;
 			if (options->listen_addrs != NULL)
 				fatal("%s line %d: ports must be specified before "
 				    "ListenAdress.\n", filename, linenum);
 			if (options->num_ports >= MAX_PORTS)
 				fatal("%s line %d: too many ports.\n",
 				    filename, linenum);
 			cp = strtok(NULL, WHITESPACE);
 			if (!cp)
 				fatal("%s line %d: missing port number.\n",
 				    filename, linenum);
 			options->ports[options->num_ports++] = atoi(cp);
 			break;

 		case sServerKeyBits:
 			intptr = &options->server_key_bits;
 parse_int:
 			cp = strtok(NULL, WHITESPACE);
 			if (!cp) {
 				fprintf(stderr, "%s line %d: missing integer value.\n",
 					filename, linenum);
 				exit(1);
 			}
 			value = atoi(cp);
 			if (*intptr == -1)
 				*intptr = value;
 			break;

 		case sLoginGraceTime:
 			intptr = &options->login_grace_time;
 			goto parse_int;

 		case sKeyRegenerationTime:
 			intptr = &options->key_regeneration_time;
 			goto parse_int;

 		case sListenAddress:
 			cp = strtok(NULL, WHITESPACE);
 			if (!cp)
 				fatal("%s line %d: missing inet addr.\n",
 				    filename, linenum);
 			add_listen_addr(options, cp);
 			break;

 		case sHostKeyFile:
 		case sDSAKeyFile:
 			charptr = (opcode == sHostKeyFile ) ?
 			    &options->host_key_file : &options->dsa_key_file;
 			cp = strtok(NULL, WHITESPACE);
 			if (!cp) {
 				fprintf(stderr, "%s line %d: missing file name.\n",
 					filename, linenum);
 				exit(1);
 			}
 			if (*charptr == NULL)
 				*charptr = tilde_expand_filename(cp, getuid());
 			break;

 		case sRandomSeedFile:
 			fprintf(stderr, "%s line %d: \"randomseed\" option is obsolete.\n",
 				filename, linenum);
 			cp = strtok(NULL, WHITESPACE);
 			break;

 		case sPermitRootLogin:
 			intptr = &options->permit_root_login;
 			cp = strtok(NULL, WHITESPACE);
 			if (!cp) {
 				fprintf(stderr, "%s line %d: missing yes/without-password/no argument.\n",
 					filename, linenum);
 				exit(1);
 			}
 			if (strcmp(cp, "without-password") == 0)
 				value = 2;
 			else if (strcmp(cp, "yes") == 0)
 				value = 1;
 			else if (strcmp(cp, "no") == 0)
 				value = 0;
 			else {
 				fprintf(stderr, "%s line %d: Bad yes/without-password/no argument: %s\n",
 					filename, linenum, cp);
 				exit(1);
 			}
 			if (*intptr == -1)
 				*intptr = value;
 			break;

 		case sIgnoreRhosts:
 			intptr = &options->ignore_rhosts;
 parse_flag:
 			cp = strtok(NULL, WHITESPACE);
 			if (!cp) {
 				fprintf(stderr, "%s line %d: missing yes/no argument.\n",
 					filename, linenum);
 				exit(1);
 			}
 			if (strcmp(cp, "yes") == 0)
 				value = 1;
 			else if (strcmp(cp, "no") == 0)
 				value = 0;
 			else {
 				fprintf(stderr, "%s line %d: Bad yes/no argument: %s\n",
 					filename, linenum, cp);
 				exit(1);
 			}
 			if (*intptr == -1)
 				*intptr = value;
 			break;

 		case sIgnoreUserKnownHosts:
 			intptr = &options->ignore_user_known_hosts;
 			goto parse_flag;

 		case sRhostsAuthentication:
 			intptr = &options->rhosts_authentication;
 			goto parse_flag;

 		case sRhostsRSAAuthentication:
 			intptr = &options->rhosts_rsa_authentication;
 			goto parse_flag;

 		case sRSAAuthentication:
 			intptr = &options->rsa_authentication;
 			goto parse_flag;

 #ifdef KRB4
 		case sKerberosAuthentication:
 			intptr = &options->kerberos_authentication;
 			goto parse_flag;

 		case sKerberosOrLocalPasswd:
 			intptr = &options->kerberos_or_local_passwd;
 			goto parse_flag;

 		case sKerberosTicketCleanup:
 			intptr = &options->kerberos_ticket_cleanup;
 			goto parse_flag;
 #endif

 #ifdef AFS
 		case sKerberosTgtPassing:
 			intptr = &options->kerberos_tgt_passing;
 			goto parse_flag;

 		case sAFSTokenPassing:
 			intptr = &options->afs_token_passing;
 			goto parse_flag;
 #endif

 		case sPasswordAuthentication:
 			intptr = &options->password_authentication;
 			goto parse_flag;

 		case sCheckMail:
 			intptr = &options->check_mail;
 			goto parse_flag;

 #ifdef SKEY
 		case sSkeyAuthentication:
 			intptr = &options->skey_authentication;
 			goto parse_flag;
 #endif

 		case sPrintMotd:
 			intptr = &options->print_motd;
 			goto parse_flag;

 		case sX11Forwarding:
 			intptr = &options->x11_forwarding;
 			goto parse_flag;

 		case sX11DisplayOffset:
 			intptr = &options->x11_display_offset;
 			goto parse_int;

 		case sStrictModes:
 			intptr = &options->strict_modes;
 			goto parse_flag;

 		case sKeepAlives:
 			intptr = &options->keepalives;
 			goto parse_flag;

 		case sEmptyPasswd:
 			intptr = &options->permit_empty_passwd;
 			goto parse_flag;

 		case sUseLogin:
 			intptr = &options->use_login;
 			goto parse_flag;

 		case sLogFacility:
 			intptr = (int *) &options->log_facility;
 			cp = strtok(NULL, WHITESPACE);
 			value = log_facility_number(cp);
 			if (value == (SyslogFacility) - 1)
 				fatal("%.200s line %d: unsupported log facility '%s'\n",
 				    filename, linenum, cp ? cp : "<NONE>");
 			if (*intptr == -1)
 				*intptr = (SyslogFacility) value;
 			break;

 		case sLogLevel:
 			intptr = (int *) &options->log_level;
 			cp = strtok(NULL, WHITESPACE);
 			value = log_level_number(cp);
 			if (value == (LogLevel) - 1)
 				fatal("%.200s line %d: unsupported log level '%s'\n",
 				    filename, linenum, cp ? cp : "<NONE>");
 			if (*intptr == -1)
 				*intptr = (LogLevel) value;
 			break;

 		case sAllowUsers:
 			while ((cp = strtok(NULL, WHITESPACE))) {
 				if (options->num_allow_users >= MAX_ALLOW_USERS)
 					fatal("%s line %d: too many allow users.\n",
 					    filename, linenum);
 				options->allow_users[options->num_allow_users++] = xstrdup(cp);
 			}
 			break;

 		case sDenyUsers:
 			while ((cp = strtok(NULL, WHITESPACE))) {
 				if (options->num_deny_users >= MAX_DENY_USERS)
 					fatal( "%s line %d: too many deny users.\n",
 					    filename, linenum);
 				options->deny_users[options->num_deny_users++] = xstrdup(cp);
 			}
 			break;

 		case sAllowGroups:
 			while ((cp = strtok(NULL, WHITESPACE))) {
 				if (options->num_allow_groups >= MAX_ALLOW_GROUPS)
 					fatal("%s line %d: too many allow groups.\n",
 					    filename, linenum);
 				options->allow_groups[options->num_allow_groups++] = xstrdup(cp);
 			}
 			break;

 		case sDenyGroups:
 			while ((cp = strtok(NULL, WHITESPACE))) {
 				if (options->num_deny_groups >= MAX_DENY_GROUPS)
 					fatal("%s line %d: too many deny groups.\n",
 					    filename, linenum);
 				options->deny_groups[options->num_deny_groups++] = xstrdup(cp);
 			}
 			break;

 		case sCiphers:
 			cp = strtok(NULL, WHITESPACE);
 			if (!ciphers_valid(cp))
 				fatal("%s line %d: Bad cipher spec '%s'.",
 				    filename, linenum, cp ? cp : "<NONE>");
 			if (options->ciphers == NULL)
 				options->ciphers = xstrdup(cp);
 			break;

 		case sProtocol:
 			intptr = &options->protocol;
 			cp = strtok(NULL, WHITESPACE);
 			value = proto_spec(cp);
 			if (value == SSH_PROTO_UNKNOWN)
 				fatal("%s line %d: Bad protocol spec '%s'.",
 				      filename, linenum, cp ? cp : "<NONE>");
 			if (*intptr == SSH_PROTO_UNKNOWN)
 				*intptr = value;
 			break;

 		default:
 			fprintf(stderr, "%s line %d: Missing handler for opcode %s (%d)\n",
 				filename, linenum, cp, opcode);
 			exit(1);
 		}
 		if (strtok(NULL, WHITESPACE) != NULL) {
 			fprintf(stderr, "%s line %d: garbage at end of line.\n",
 				filename, linenum);
 			exit(1);
 		}
 	}
 	fclose(f);
 	if (bad_options > 0) {
 		fprintf(stderr, "%s: terminating, %d bad configuration options\n",
 			filename, bad_options);
 		exit(1);
 	}
 }
	/*
	*
	* servconf.c
	*
	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	*
	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	* All rights reserved
	*
	* Created: Mon Aug 21 15:48:58 1995 ylo
	*
	*/

	#include "includes.h"
	RCSID("$Id: servconf.c,v 1.12 2000/04/16 01:18:45 damien Exp $");

	#include "ssh.h"
	#include "servconf.h"
	#include "xmalloc.h"
	#include "compat.h"

	/* add listen address */
	void add_listen_addr(ServerOptions options, char addr);

	/* Initializes the server options to their default values. */

	void
	initialize_server_options(ServerOptions *options)
	{
	memset(options, 0, sizeof(*options));
	options->num_ports = 0;
	options->ports_from_cmdline = 0;
	options->listen_addrs = NULL;
	options->host_key_file = NULL;
	options->dsa_key_file = NULL;
	options->server_key_bits = -1;
	options->login_grace_time = -1;
	options->key_regeneration_time = -1;
	options->permit_root_login = -1;
	options->ignore_rhosts = -1;
	options->ignore_user_known_hosts = -1;
	options->print_motd = -1;
	options->check_mail = -1;
	options->x11_forwarding = -1;
	options->x11_display_offset = -1;
	options->strict_modes = -1;
	options->keepalives = -1;
	options->log_facility = (SyslogFacility) - 1;
	options->log_level = (LogLevel) - 1;
	options->rhosts_authentication = -1;
	options->rhosts_rsa_authentication = -1;
	options->rsa_authentication = -1;
	#ifdef KRB4
	options->kerberos_authentication = -1;
	options->kerberos_or_local_passwd = -1;
	options->kerberos_ticket_cleanup = -1;
	#endif
	#ifdef AFS
	options->kerberos_tgt_passing = -1;
	options->afs_token_passing = -1;
	#endif
	options->password_authentication = -1;
	#ifdef SKEY
	options->skey_authentication = -1;
	#endif
	options->permit_empty_passwd = -1;
	options->use_login = -1;
	options->num_allow_users = 0;
	options->num_deny_users = 0;
	options->num_allow_groups = 0;
	options->num_deny_groups = 0;
	options->ciphers = NULL;
	options->protocol = SSH_PROTO_UNKNOWN;
	}

	void
	fill_default_server_options(ServerOptions *options)
	{
	if (options->num_ports == 0)
	options->ports[options->num_ports++] = SSH_DEFAULT_PORT;
	if (options->listen_addrs == NULL)
	add_listen_addr(options, NULL);
	if (options->host_key_file == NULL)
	options->host_key_file = HOST_KEY_FILE;
	if (options->dsa_key_file == NULL)
	options->dsa_key_file = DSA_KEY_FILE;
	if (options->server_key_bits == -1)
	options->server_key_bits = 768;
	if (options->login_grace_time == -1)
	options->login_grace_time = 600;
	if (options->key_regeneration_time == -1)
	options->key_regeneration_time = 3600;
	if (options->permit_root_login == -1)
	options->permit_root_login = 1; /* yes */
	if (options->ignore_rhosts == -1)
	options->ignore_rhosts = 1;
	if (options->ignore_user_known_hosts == -1)
	options->ignore_user_known_hosts = 0;
	if (options->check_mail == -1)
	options->check_mail = 0;
	if (options->print_motd == -1)
	options->print_motd = 1;
	if (options->x11_forwarding == -1)
	options->x11_forwarding = 0;
	if (options->x11_display_offset == -1)
	options->x11_display_offset = 10;
	if (options->strict_modes == -1)
	options->strict_modes = 1;
	if (options->keepalives == -1)
	options->keepalives = 1;
	if (options->log_facility == (SyslogFacility) (-1))
	options->log_facility = SYSLOG_FACILITY_AUTH;
	if (options->log_level == (LogLevel) (-1))
	options->log_level = SYSLOG_LEVEL_INFO;
	if (options->rhosts_authentication == -1)
	options->rhosts_authentication = 0;
	if (options->rhosts_rsa_authentication == -1)
	options->rhosts_rsa_authentication = 0;
	if (options->rsa_authentication == -1)
	options->rsa_authentication = 1;
	#ifdef KRB4
	if (options->kerberos_authentication == -1)
	options->kerberos_authentication = (access(KEYFILE, R_OK) == 0);
	if (options->kerberos_or_local_passwd == -1)
	options->kerberos_or_local_passwd = 1;
	if (options->kerberos_ticket_cleanup == -1)
	options->kerberos_ticket_cleanup = 1;
	#endif /* KRB4 */
	#ifdef AFS
	if (options->kerberos_tgt_passing == -1)
	options->kerberos_tgt_passing = 0;
	if (options->afs_token_passing == -1)
	options->afs_token_passing = k_hasafs();
	#endif /* AFS */
	if (options->password_authentication == -1)
	options->password_authentication = 1;
	#ifdef SKEY
	if (options->skey_authentication == -1)
	options->skey_authentication = 1;
	#endif
	if (options->permit_empty_passwd == -1)
	options->permit_empty_passwd = 0;
	if (options->use_login == -1)
	options->use_login = 0;
	if (options->protocol == SSH_PROTO_UNKNOWN)
	options->protocol = SSH_PROTO_1;
	}

	#define WHITESPACE " \t\r\n"

	/* Keyword tokens. */
	typedef enum {
	sBadOption, /* == unknown option */
	sPort, sHostKeyFile, sServerKeyBits, sLoginGraceTime, sKeyRegenerationTime,
	sPermitRootLogin, sLogFacility, sLogLevel,
	sRhostsAuthentication, sRhostsRSAAuthentication, sRSAAuthentication,
	#ifdef KRB4
	sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,
	#endif
	#ifdef AFS
	sKerberosTgtPassing, sAFSTokenPassing,
	#endif
	#ifdef SKEY
	sSkeyAuthentication,
	#endif
	sPasswordAuthentication, sListenAddress,
	sPrintMotd, sIgnoreRhosts, sX11Forwarding, sX11DisplayOffset,
	sStrictModes, sEmptyPasswd, sRandomSeedFile, sKeepAlives, sCheckMail,
	sUseLogin, sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups,
	sIgnoreUserKnownHosts, sDSAKeyFile, sCiphers, sProtocol
	} ServerOpCodes;

	/* Textual representation of the tokens. */
	static struct {
	const char *name;
	ServerOpCodes opcode;
	} keywords[] = {
	{ "port", sPort },
	{ "hostkey", sHostKeyFile },
	{ "dsakey", sDSAKeyFile },
	{ "serverkeybits", sServerKeyBits },
	{ "logingracetime", sLoginGraceTime },
	{ "keyregenerationinterval", sKeyRegenerationTime },
	{ "permitrootlogin", sPermitRootLogin },
	{ "syslogfacility", sLogFacility },
	{ "loglevel", sLogLevel },
	{ "rhostsauthentication", sRhostsAuthentication },
	{ "rhostsrsaauthentication", sRhostsRSAAuthentication },
	{ "rsaauthentication", sRSAAuthentication },
	#ifdef KRB4
	{ "kerberosauthentication", sKerberosAuthentication },
	{ "kerberosorlocalpasswd", sKerberosOrLocalPasswd },
	{ "kerberosticketcleanup", sKerberosTicketCleanup },
	#endif
	#ifdef AFS
	{ "kerberostgtpassing", sKerberosTgtPassing },
	{ "afstokenpassing", sAFSTokenPassing },
	#endif
	{ "passwordauthentication", sPasswordAuthentication },
	#ifdef SKEY
	{ "skeyauthentication", sSkeyAuthentication },
	#endif
	{ "checkmail", sCheckMail },
	{ "listenaddress", sListenAddress },
	{ "printmotd", sPrintMotd },
	{ "ignorerhosts", sIgnoreRhosts },
	{ "ignoreuserknownhosts", sIgnoreUserKnownHosts },
	{ "x11forwarding", sX11Forwarding },
	{ "x11displayoffset", sX11DisplayOffset },
	{ "strictmodes", sStrictModes },
	{ "permitemptypasswords", sEmptyPasswd },
	{ "uselogin", sUseLogin },
	{ "randomseed", sRandomSeedFile },
	{ "keepalive", sKeepAlives },
	{ "allowusers", sAllowUsers },
	{ "denyusers", sDenyUsers },
	{ "allowgroups", sAllowGroups },
	{ "denygroups", sDenyGroups },
	{ "ciphers", sCiphers },
	{ "protocol", sProtocol },
	{ NULL, 0 }
	};

	/*
	* Returns the number of the token pointed to by cp of length len. Never
	* returns if the token is not known.
	*/

	static ServerOpCodes
	parse_token(const char cp, const char filename,
	int linenum)
	{
	unsigned int i;

	for (i = 0; keywords[i].name; i++)
	if (strcasecmp(cp, keywords[i].name) == 0)
	return keywords[i].opcode;

	fprintf(stderr, "%s: line %d: Bad configuration option: %s\n",
	filename, linenum, cp);
	return sBadOption;
	}

	/*
	* add listen address
	*/
	void
	add_listen_addr(ServerOptions options, char addr)
	{
	extern int IPv4or6;
	struct addrinfo hints, ai, aitop;
	char strport[NI_MAXSERV];
	int gaierr;
	int i;

	if (options->num_ports == 0)
	options->ports[options->num_ports++] = SSH_DEFAULT_PORT;
	for (i = 0; i < options->num_ports; i++) {
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = IPv4or6;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = (addr == NULL) ? AI_PASSIVE : 0;
	snprintf(strport, sizeof strport, "%d", options->ports[i]);
	if ((gaierr = getaddrinfo(addr, strport, &hints, &aitop)) != 0)
	fatal("bad addr or host: %s (%s)\n",
	addr ? addr : "<NULL>",
	gai_strerror(gaierr));
	for (ai = aitop; ai->ai_next; ai = ai->ai_next)
	;
	ai->ai_next = options->listen_addrs;
	options->listen_addrs = aitop;
	}
	}

	/* Reads the server configuration file. */

	void
	read_server_config(ServerOptions options, const char filename)
	{
	FILE *f;
	char line[1024];
	char cp, *charptr;
	int linenum, *intptr, value;
	int bad_options = 0;
	ServerOpCodes opcode;

	f = fopen(filename, "r");
	if (!f) {
	perror(filename);
	exit(1);
	}
	linenum = 0;
	while (fgets(line, sizeof(line), f)) {
	linenum++;
	cp = line + strspn(line, WHITESPACE);
	if (!cp \|\| cp == '#')
	continue;
	cp = strtok(cp, WHITESPACE);
	opcode = parse_token(cp, filename, linenum);
	switch (opcode) {
	case sBadOption:
	bad_options++;
	continue;
	case sPort:
	/* ignore ports from configfile if cmdline specifies ports */
	if (options->ports_from_cmdline)
	continue;
	if (options->listen_addrs != NULL)
	fatal("%s line %d: ports must be specified before "
	"ListenAdress.\n", filename, linenum);
	if (options->num_ports >= MAX_PORTS)
	fatal("%s line %d: too many ports.\n",
	filename, linenum);
	cp = strtok(NULL, WHITESPACE);
	if (!cp)
	fatal("%s line %d: missing port number.\n",
	filename, linenum);
	options->ports[options->num_ports++] = atoi(cp);
	break;

	case sServerKeyBits:
	intptr = &options->server_key_bits;
	parse_int:
	cp = strtok(NULL, WHITESPACE);
	if (!cp) {
	fprintf(stderr, "%s line %d: missing integer value.\n",
	filename, linenum);
	exit(1);
	}
	value = atoi(cp);
	if (*intptr == -1)
	*intptr = value;
	break;

	case sLoginGraceTime:
	intptr = &options->login_grace_time;
	goto parse_int;

	case sKeyRegenerationTime:
	intptr = &options->key_regeneration_time;
	goto parse_int;

	case sListenAddress:
	cp = strtok(NULL, WHITESPACE);
	if (!cp)
	fatal("%s line %d: missing inet addr.\n",
	filename, linenum);
	add_listen_addr(options, cp);
	break;

	case sHostKeyFile:
	case sDSAKeyFile:
	charptr = (opcode == sHostKeyFile ) ?
	&options->host_key_file : &options->dsa_key_file;
	cp = strtok(NULL, WHITESPACE);
	if (!cp) {
	fprintf(stderr, "%s line %d: missing file name.\n",
	filename, linenum);
	exit(1);
	}
	if (*charptr == NULL)
	*charptr = tilde_expand_filename(cp, getuid());
	break;

	case sRandomSeedFile:
	fprintf(stderr, "%s line %d: \"randomseed\" option is obsolete.\n",
	filename, linenum);
	cp = strtok(NULL, WHITESPACE);
	break;

	case sPermitRootLogin:
	intptr = &options->permit_root_login;
	cp = strtok(NULL, WHITESPACE);
	if (!cp) {
	fprintf(stderr, "%s line %d: missing yes/without-password/no argument.\n",
	filename, linenum);
	exit(1);
	}
	if (strcmp(cp, "without-password") == 0)
	value = 2;
	else if (strcmp(cp, "yes") == 0)
	value = 1;
	else if (strcmp(cp, "no") == 0)
	value = 0;
	else {
	fprintf(stderr, "%s line %d: Bad yes/without-password/no argument: %s\n",
	filename, linenum, cp);
	exit(1);
	}
	if (*intptr == -1)
	*intptr = value;
	break;

	case sIgnoreRhosts:
	intptr = &options->ignore_rhosts;
	parse_flag:
	cp = strtok(NULL, WHITESPACE);
	if (!cp) {
	fprintf(stderr, "%s line %d: missing yes/no argument.\n",
	filename, linenum);
	exit(1);
	}
	if (strcmp(cp, "yes") == 0)
	value = 1;
	else if (strcmp(cp, "no") == 0)
	value = 0;
	else {
	fprintf(stderr, "%s line %d: Bad yes/no argument: %s\n",
	filename, linenum, cp);
	exit(1);
	}
	if (*intptr == -1)
	*intptr = value;
	break;

	case sIgnoreUserKnownHosts:
	intptr = &options->ignore_user_known_hosts;
	goto parse_flag;

	case sRhostsAuthentication:
	intptr = &options->rhosts_authentication;
	goto parse_flag;

	case sRhostsRSAAuthentication:
	intptr = &options->rhosts_rsa_authentication;
	goto parse_flag;

	case sRSAAuthentication:
	intptr = &options->rsa_authentication;
	goto parse_flag;

	#ifdef KRB4
	case sKerberosAuthentication:
	intptr = &options->kerberos_authentication;
	goto parse_flag;

	case sKerberosOrLocalPasswd:
	intptr = &options->kerberos_or_local_passwd;
	goto parse_flag;

	case sKerberosTicketCleanup:
	intptr = &options->kerberos_ticket_cleanup;
	goto parse_flag;
	#endif

	#ifdef AFS
	case sKerberosTgtPassing:
	intptr = &options->kerberos_tgt_passing;
	goto parse_flag;

	case sAFSTokenPassing:
	intptr = &options->afs_token_passing;
	goto parse_flag;
	#endif

	case sPasswordAuthentication:
	intptr = &options->password_authentication;
	goto parse_flag;

	case sCheckMail:
	intptr = &options->check_mail;
	goto parse_flag;

	#ifdef SKEY
	case sSkeyAuthentication:
	intptr = &options->skey_authentication;
	goto parse_flag;
	#endif

	case sPrintMotd:
	intptr = &options->print_motd;
	goto parse_flag;

	case sX11Forwarding:
	intptr = &options->x11_forwarding;
	goto parse_flag;

	case sX11DisplayOffset:
	intptr = &options->x11_display_offset;
	goto parse_int;

	case sStrictModes:
	intptr = &options->strict_modes;
	goto parse_flag;

	case sKeepAlives:
	intptr = &options->keepalives;
	goto parse_flag;

	case sEmptyPasswd:
	intptr = &options->permit_empty_passwd;
	goto parse_flag;

	case sUseLogin:
	intptr = &options->use_login;
	goto parse_flag;

	case sLogFacility:
	intptr = (int *) &options->log_facility;
	cp = strtok(NULL, WHITESPACE);
	value = log_facility_number(cp);
	if (value == (SyslogFacility) - 1)
	fatal("%.200s line %d: unsupported log facility '%s'\n",
	filename, linenum, cp ? cp : "<NONE>");
	if (*intptr == -1)
	*intptr = (SyslogFacility) value;
	break;

	case sLogLevel:
	intptr = (int *) &options->log_level;
	cp = strtok(NULL, WHITESPACE);
	value = log_level_number(cp);
	if (value == (LogLevel) - 1)
	fatal("%.200s line %d: unsupported log level '%s'\n",
	filename, linenum, cp ? cp : "<NONE>");
	if (*intptr == -1)
	*intptr = (LogLevel) value;
	break;

	case sAllowUsers:
	while ((cp = strtok(NULL, WHITESPACE))) {
	if (options->num_allow_users >= MAX_ALLOW_USERS)
	fatal("%s line %d: too many allow users.\n",
	filename, linenum);
	options->allow_users[options->num_allow_users++] = xstrdup(cp);
	}
	break;

	case sDenyUsers:
	while ((cp = strtok(NULL, WHITESPACE))) {
	if (options->num_deny_users >= MAX_DENY_USERS)
	fatal( "%s line %d: too many deny users.\n",
	filename, linenum);
	options->deny_users[options->num_deny_users++] = xstrdup(cp);
	}
	break;

	case sAllowGroups:
	while ((cp = strtok(NULL, WHITESPACE))) {
	if (options->num_allow_groups >= MAX_ALLOW_GROUPS)
	fatal("%s line %d: too many allow groups.\n",
	filename, linenum);
	options->allow_groups[options->num_allow_groups++] = xstrdup(cp);
	}
	break;

	case sDenyGroups:
	while ((cp = strtok(NULL, WHITESPACE))) {
	if (options->num_deny_groups >= MAX_DENY_GROUPS)
	fatal("%s line %d: too many deny groups.\n",
	filename, linenum);
	options->deny_groups[options->num_deny_groups++] = xstrdup(cp);
	}
	break;

	case sCiphers:
	cp = strtok(NULL, WHITESPACE);
	if (!ciphers_valid(cp))
	fatal("%s line %d: Bad cipher spec '%s'.",
	filename, linenum, cp ? cp : "<NONE>");
	if (options->ciphers == NULL)
	options->ciphers = xstrdup(cp);
	break;

	case sProtocol:
	intptr = &options->protocol;
	cp = strtok(NULL, WHITESPACE);
	value = proto_spec(cp);
	if (value == SSH_PROTO_UNKNOWN)
	fatal("%s line %d: Bad protocol spec '%s'.",
	filename, linenum, cp ? cp : "<NONE>");
	if (*intptr == SSH_PROTO_UNKNOWN)
	*intptr = value;
	break;

	default:
	fprintf(stderr, "%s line %d: Missing handler for opcode %s (%d)\n",
	filename, linenum, cp, opcode);
	exit(1);
	}
	if (strtok(NULL, WHITESPACE) != NULL) {
	fprintf(stderr, "%s line %d: garbage at end of line.\n",
	filename, linenum);
	exit(1);
	}
	}
	fclose(f);
	if (bad_options > 0) {
	fprintf(stderr, "%s: terminating, %d bad configuration options\n",
	filename, bad_options);
	exit(1);
	}
	}