R6.6 is the Xorg base-lineXORG-MAINXORG-STABLE

2 files changed, 791 insertions, 0 deletions

diff --git a/xhost.c b/xhost.c
new file mode 100644
index 0000000..7632ec4
--- /dev/null
+++ b/xhost.c
@@ -0,0 +1,657 @@
+/* $Xorg: xhost.c,v 1.4 2001/02/09 02:05:46 xorgcvs Exp $ */
+/*
+
+Copyright 1985, 1986, 1987, 1998  The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall
+not be used in advertising or otherwise to promote the sale, use or
+other dealings in this Software without prior written authorization
+from The Open Group.
+
+*/
+
+#if defined(TCPCONN) || defined(STREAMSCONN)
+#define NEEDSOCKETS
+#endif
+#ifdef UNIXCONN
+#define NEEDSOCKETS
+#endif
+#ifdef DNETCONN
+#define NEEDSOCKETS
+#endif
+
+#include <X11/Xlib.h>
+#include <X11/Xos.h>
+#include <X11/Xproto.h>
+#include <X11/Xfuncs.h>
+#include <stdio.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <ctype.h>
+#include <X11/Xauth.h>
+#include <X11/Xmu/Error.h>
+
+#ifdef NEEDSOCKETS
+#ifdef att
+typedef unsigned short unsign16;
+typedef unsigned long unsign32;
+typedef short sign16;
+typedef long sign32;
+#include <interlan/socket.h>
+#include <interlan/netdb.h>
+#include <interlan/in.h>
+#else
+#include <sys/socket.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#endif
+#endif /* NEEDSOCKETS */
+
+#ifdef notdef
+#include <arpa/inet.h>
+	bogus definition of inet_makeaddr() in BSD 4.2 and Ultrix
+#else
+#if !defined(hpux) && !defined(NCR)
+extern unsigned long inet_makeaddr();
+#endif
+#endif
+#ifdef DNETCONN
+#include <netdnet/dn.h>
+#include <netdnet/dnetdb.h>
+#endif
+
+#ifdef SECURE_RPC
+#include <pwd.h>
+#include <rpc/rpc.h>
+#ifdef X_POSIX_C_SOURCE
+#define _POSIX_C_SOURCE X_POSIX_C_SOURCE
+#include <limits.h>
+#undef _POSIX_C_SOURCE
+#else
+#if defined(X_NOT_POSIX) || defined(_POSIX_SOURCE)
+#include <limits.h>
+#else
+#define _POSIX_SOURCE
+#include <limits.h>
+#undef _POSIX_SOURCE
+#endif
+#endif
+#ifndef NGROUPS_MAX
+#include <sys/param.h>
+#define NGROUPS_MAX NGROUPS
+#endif
+#endif
+ 
+static int local_xerror();
+static char *get_hostname();
+
+#ifdef SIGNALRETURNSINT
+#define signal_t int
+#else
+#define signal_t void
+#endif
+static signal_t nameserver_lost();
+
+#define NAMESERVER_TIMEOUT 5	/* time to wait for nameserver */
+
+int nameserver_timedout;
+ 
+char *ProgramName;
+
+#ifdef NEEDSOCKETS
+static int XFamily(af)
+    int af;
+{
+    int i;
+    static struct _familyMap {
+	int af, xf;
+    } familyMap[] = {
+#ifdef	AF_DECnet
+        { AF_DECnet, FamilyDECnet },
+#endif
+#ifdef	AF_CHAOS
+        { AF_CHAOS, FamilyChaos },
+#endif
+#ifdef	AF_INET
+        { AF_INET, FamilyInternet },
+#endif
+};
+
+#define FAMILIES ((sizeof familyMap)/(sizeof familyMap[0]))
+
+    for (i = 0; i < FAMILIES; i++)
+	if (familyMap[i].af == af) return familyMap[i].xf;
+    return -1;
+}
+#endif /* NEEDSOCKETS */
+
+Display *dpy;
+
+main(argc, argv)
+    int argc;
+    char **argv;
+{
+    register char *arg;
+    int i, nhosts = 0;
+    char *hostname;
+    int nfailed = 0;
+    XHostAddress *list;
+    Bool enabled = False;
+#ifdef DNETCONN
+    char *dnet_htoa();
+    struct nodeent *np;
+    struct dn_naddr *nlist, dnaddr, *dnaddrp, *dnet_addr();
+    char *cp;
+#endif
+ 
+    ProgramName = argv[0];
+
+    if ((dpy = XOpenDisplay(NULL)) == NULL) {
+	fprintf(stderr, "%s:  unable to open display \"%s\"\n",
+		ProgramName, XDisplayName (NULL));
+	exit(1);
+    }
+
+    XSetErrorHandler(local_xerror);
+ 
+ 
+    if (argc == 1) {
+#ifdef DNETCONN
+	setnodeent(1);		/* keep the database accessed */
+#endif
+	sethostent(1);		/* don't close the data base each time */
+	list = XListHosts(dpy, &nhosts, &enabled);
+	if (enabled)
+	    printf ("access control enabled, only authorized clients can connect\n");
+	else
+	    printf ("access control disabled, clients can connect from any host\n");
+
+	if (nhosts != 0) {
+	    for (i = 0; i < nhosts; i++ )  {
+		hostname = get_hostname(&list[i]);
+		if (hostname) {
+		    switch (list[i].family) {
+		    case FamilyInternet:
+			printf("INET:");
+			break;
+		    case FamilyDECnet:
+			printf("DNET:");
+			break;
+		    case FamilyNetname:
+			printf("NIS:");
+			break;
+		    case FamilyKrb5Principal:
+			printf("KRB:");
+			break;
+		    case FamilyLocalHost:
+			printf("LOCAL:");
+			break;
+		    }
+		    printf ("%s", hostname);
+		} else {
+		    printf ("<unknown address in family %d>",
+			    list[i].family);
+		}
+		if (nameserver_timedout) {
+		    printf("\t(no nameserver response within %d seconds)\n",
+			   NAMESERVER_TIMEOUT);
+		    nameserver_timedout = 0;
+		} else
+		    printf("\n");
+	    }
+	    free(list);
+	    endhostent();
+	}
+	exit(0);
+    }
+ 
+    if (argc == 2 && !strcmp(argv[1], "-help")) {
+	fprintf(stderr, "usage: %s [[+-]hostname ...]\n", argv[0]);
+	exit(1);
+    }
+
+    for (i = 1; i < argc; i++) {
+	arg = argv[i];
+	if (*arg == '-') {
+	    
+	    if (!argv[i][1] && ((i+1) == argc)) {
+		printf ("access control enabled, only authorized clients can connect\n");
+		XEnableAccessControl(dpy);
+	    } else {
+		arg = argv[i][1]? &argv[i][1] : argv[++i];
+		if (!change_host (dpy, arg, False)) {
+		    fprintf (stderr, "%s:  bad hostname \"%s\"\n",
+			     ProgramName, arg);
+		    nfailed++;
+		}
+	    }
+	} else {
+	    if (*arg == '+' && !argv[i][1] && ((i+1) == argc)) {
+		printf ("access control disabled, clients can connect from any host\n");
+		XDisableAccessControl(dpy);
+	    } else {
+		if (*arg == '+') {
+		    arg = argv[i][1]? &argv[i][1] : argv[++i];
+		}
+		if (!change_host (dpy, arg, True)) {
+		    fprintf (stderr, "%s:  bad hostname \"%s\"\n",
+			     ProgramName, arg);
+		    nfailed++;
+		}
+	    }
+	}
+    }
+    XCloseDisplay (dpy);	/* does an XSync first */
+    exit(nfailed);
+}
+
+ 
+
+/*
+ * change_host - edit the list of hosts that may connect to the server;
+ * it parses DECnet names (expo::), Internet addresses (18.30.0.212), or
+ * Internet names (expo.lcs.mit.edu); if 4.3bsd macro h_addr is defined
+ * (from <netdb.h>), it will add or remove all addresses with the given
+ * address.
+ */
+
+int change_host (dpy, name, add)
+    Display *dpy;
+    char *name;
+    Bool add;
+{
+    struct hostent *hp;
+    XHostAddress ha;
+    char *lname;
+    int namelen, i, family = FamilyWild;
+#ifdef K5AUTH
+    krb5_principal princ;
+    krb5_data kbuf;
+#endif
+#ifdef NEEDSOCKETS
+    static struct in_addr addr;	/* so we can point at it */
+#endif
+    char *cp;
+#ifdef DNETCONN
+    struct dn_naddr *dnaddrp;
+    struct nodeent *np;
+    static struct dn_naddr dnaddr;
+#endif				/* DNETCONN */
+    static char *add_msg = "being added to access control list";
+    static char *remove_msg = "being removed from access control list";
+
+    namelen = strlen(name);
+    if ((lname = (char *)malloc(namelen+1)) == NULL) {
+	fprintf (stderr, "%s: malloc bombed in change_host\n", ProgramName);
+	exit (1);
+    }
+    for (i = 0; i < namelen; i++) {
+	lname[i] = tolower(name[i]);
+    }
+    lname[namelen] = '\0';
+    if (!strncmp("inet:", lname, 5)) {
+#if defined(TCPCONN) || defined(STREAMSCONN)
+	family = FamilyInternet;
+	name += 5;
+#else
+	fprintf (stderr, "%s: not compiled for TCP/IP\n", ProgramName);
+	return 0;
+#endif
+    }
+    if (!strncmp("dnet:", lname, 5)) {
+#ifdef DNETCONN
+	family = FamilyDECnet;
+	name += 5;
+#else
+	fprintf (stderr, "%s: not compiled for DECnet\n", ProgramName);
+	return 0;
+#endif
+    }
+    if (!strncmp("nis:", lname, 4)) {
+#ifdef SECURE_RPC
+	family = FamilyNetname;
+	name += 4;
+#else
+	fprintf (stderr, "%s: not compiled for Secure RPC\n", ProgramName);
+	return 0;
+#endif
+    }
+    if (!strncmp("krb:", lname, 4)) {
+#ifdef K5AUTH
+	family = FamilyKrb5Principal;
+	name +=4;
+#else
+	fprintf (stderr, "%s: not compiled for Kerberos 5\n", ProgramName);
+	return 0;
+#endif
+    }
+    if (!strncmp("local:", lname, 6)) {
+	family = FamilyLocalHost;
+    }
+    if (family == FamilyWild && (cp = strchr(lname, ':'))) {
+	*cp = '\0';
+	fprintf (stderr, "%s: unknown address family \"%s\"\n",
+		 ProgramName, lname);
+	return 0;
+    }
+    free(lname);
+
+#ifdef DNETCONN
+    if (family == FamilyDECnet ||
+	(cp = strchr(name, ':')) && (*(cp + 1) == ':') &&
+	!(*cp = '\0')) {
+	ha.family = FamilyDECnet;
+	if (dnaddrp = dnet_addr(name)) {
+	    dnaddr = *dnaddrp;
+	} else {
+	    if ((np = getnodebyname (name)) == NULL) {
+		fprintf (stderr, "%s:  unable to get node name for \"%s::\"\n",
+			 ProgramName, name);
+		return 0;
+	    }
+	    dnaddr.a_len = np->n_length;
+	    memmove( dnaddr.a_addr, np->n_addr, np->n_length);
+	}
+	ha.length = sizeof(struct dn_naddr);
+	ha.address = (char *)&dnaddr;
+	if (add) {
+	    XAddHost (dpy, &ha);
+	    printf ("%s:: %s\n", name, add_msg);
+	} else {
+	    XRemoveHost (dpy, &ha);
+	    printf ("%s:: %s\n", name, remove_msg);
+	}
+	return 1;
+    }
+#endif				/* DNETCONN */
+#ifdef K5AUTH
+    if (family == FamilyKrb5Principal) {
+	krb5_error_code retval;
+
+	retval = krb5_parse_name(name, &princ);
+	if (retval) {
+	    krb5_init_ets();	/* init krb errs for error_message() */
+	    fprintf(stderr, "%s: cannot parse Kerberos name: %s\n",
+		    ProgramName, error_message(retval));
+	    return 0;
+	}
+	XauKrb5Encode(princ, &kbuf);
+	ha.length = kbuf.length;
+	ha.address = kbuf.data;
+	ha.family = family;
+	if (add)
+	    XAddHost(dpy, &ha);
+	else
+	    XRemoveHost(dpy, &ha);
+	krb5_free_principal(princ);
+	free(kbuf.data);
+	printf( "%s %s\n", name, add ? add_msg : remove_msg);
+	return 1;
+    }
+#endif
+    if (family == FamilyLocalHost) {
+	ha.length = 0;
+	ha.address = "";
+	ha.family = family;
+	if (add)
+	    XAddHost(dpy, &ha);
+	else
+	    XRemoveHost(dpy, &ha);
+	printf( "non-network local connections %s\n", add ? add_msg : remove_msg);
+	return 1;
+    }
+    /*
+     * If it has an '@', it's a netname
+     */
+    if ((family == FamilyNetname && (cp = strchr(name, '@'))) ||
+	(cp = strchr(name, '@'))) {
+        char *netname = name;
+#ifdef SECURE_RPC
+	static char username[MAXNETNAMELEN];
+
+	if (!cp[1]) {
+	    struct passwd *pwd;
+	    static char domainname[128];
+
+	    *cp = '\0';
+	    pwd = getpwnam(name);
+	    if (!pwd) {
+		fprintf(stderr, "no such user \"%s\"\n", name);
+		return 0;
+	    }
+	    getdomainname(domainname, sizeof(domainname));
+	    if (!user2netname(username, pwd->pw_uid, domainname)) {
+		fprintf(stderr, "failed to get netname for \"%s\"\n", name);
+		return 0;
+	    }
+	    netname = username;
+	}
+#endif
+	ha.family = FamilyNetname;
+	ha.length = strlen(netname);
+	ha.address = netname;
+	if (add)
+	    XAddHost (dpy, &ha);
+	else
+	    XRemoveHost (dpy, &ha);
+	if (netname != name)
+	    printf ("%s@ (%s) %s\n", name, netname, add ? add_msg : remove_msg);
+	else
+	    printf ("%s %s\n", netname, add ? add_msg : remove_msg);
+        return 1;
+    }
+#ifdef NEEDSOCKETS
+    /*
+     * First see if inet_addr() can grok the name; if so, then use it.
+     */
+    if ((addr.s_addr = inet_addr(name)) != -1) {
+	ha.family = FamilyInternet;
+	ha.length = 4;		/* but for Cray would be sizeof(addr.s_addr) */
+	ha.address = (char *)&addr; /* but for Cray would be &addr.s_addr */
+	if (add) {
+	    XAddHost (dpy, &ha);
+	    printf ("%s %s\n", name, add_msg);
+	} else {
+	    XRemoveHost (dpy, &ha);
+	    printf ("%s %s\n", name, remove_msg);
+	}
+	return 1;
+    } 
+    /*
+     * Is it in the namespace?
+     */
+    else if (((hp = gethostbyname(name)) == (struct hostent *)NULL)
+	     || hp->h_addrtype != AF_INET) {
+	return 0;
+    } else {
+	ha.family = XFamily(hp->h_addrtype);
+	ha.length = hp->h_length;
+#ifdef h_addr			/* new 4.3bsd version of gethostent */
+    {
+	char **list;
+
+	/* iterate over the hosts */
+	for (list = hp->h_addr_list; *list; list++) {
+	    ha.address = *list;
+	    if (add) {
+		XAddHost (dpy, &ha);
+	    } else {
+		XRemoveHost (dpy, &ha);
+	    }
+	}
+    }
+#else
+	ha.address = hp->h_addr;
+	if (add) {
+	    XAddHost (dpy, &ha);
+	} else {
+	    XRemoveHost (dpy, &ha);
+	}
+#endif
+	printf ("%s %s\n", name, add ? add_msg : remove_msg);
+	return 1;
+    }
+#else /* NEEDSOCKETS */
+    return 0;
+#endif /* NEEDSOCKETS */
+}
+
+
+/*
+ * get_hostname - Given an internet address, return a name (CHARON.MIT.EDU)
+ * or a string representing the address (18.58.0.13) if the name cannot
+ * be found.
+ */
+
+jmp_buf env;
+
+static char *get_hostname (ha)
+    XHostAddress *ha;
+{
+#if defined(TCPCONN) || defined(STREAMSCONN)
+    struct hostent *hp = NULL;
+    char *inet_ntoa();
+#endif
+#ifdef DNETCONN
+    struct nodeent *np;
+    static char nodeaddr[5 + 2 * DN_MAXADDL];
+#endif				/* DNETCONN */
+#ifdef K5AUTH
+    krb5_principal princ;
+    krb5_data kbuf;
+    char *kname;
+    static char kname_out[255];
+#endif
+
+#if defined(TCPCONN) || defined(STREAMSCONN)
+    if (ha->family == FamilyInternet) {
+#ifdef CRAY
+	struct in_addr t_addr;
+	bzero((char *)&t_addr, sizeof(t_addr));
+	bcopy(ha->address, (char *)&t_addr, 4);
+	ha->address = (char *)&t_addr;
+#endif
+	/* gethostbyaddr can take a LONG time if the host does not exist.
+	   Assume that if it does not respond in NAMESERVER_TIMEOUT seconds
+	   that something is wrong and do not make the user wait.
+	   gethostbyaddr will continue after a signal, so we have to
+	   jump out of it. 
+	   */
+	signal(SIGALRM, nameserver_lost);
+	alarm(4);
+	if (setjmp(env) == 0) {
+	    hp = gethostbyaddr (ha->address, ha->length, AF_INET);
+	}
+	alarm(0);
+	if (hp)
+	    return (hp->h_name);
+	else return (inet_ntoa(*((struct in_addr *)(ha->address))));
+    }
+#endif
+    if (ha->family == FamilyNetname) {
+	static char netname[512];
+	int len;
+#ifdef SECURE_RPC
+	int uid, gid, gidlen, gidlist[NGROUPS_MAX];
+#endif
+
+	if (ha->length < sizeof(netname) - 1)
+	    len = ha->length;
+	else
+	    len = sizeof(netname) - 1;
+	memmove( netname, ha->address, len);
+	netname[len] = '\0';
+#ifdef SECURE_RPC
+	if (netname2user(netname, &uid, &gid, &gidlen, gidlist)) {
+	    struct passwd *pwd;
+	    char *cp;
+
+	    pwd = getpwuid(uid);
+	    if (pwd)
+		sprintf(netname, "%s@ (%*.*s)", pwd->pw_name,
+			ha->length, ha->length, ha->address);
+	}
+#endif
+	return (netname);
+    }
+#ifdef DNETCONN
+    if (ha->family == FamilyDECnet) {
+	struct dn_naddr *addr_ptr = (struct dn_naddr *) ha->address;
+
+	if (np = getnodebyaddr(addr_ptr->a_addr, addr_ptr->a_len, AF_DECnet)) {
+	    sprintf(nodeaddr, "%s", np->n_name);
+	} else {
+	    sprintf(nodeaddr, "%s", dnet_htoa(ha->address));
+	}
+	return(nodeaddr);
+    }
+#endif
+#ifdef K5AUTH
+    if (ha->family == FamilyKrb5Principal) {
+	kbuf.data = ha->address;
+	kbuf.length = ha->length;
+	XauKrb5Decode(kbuf, &princ);
+	krb5_unparse_name(princ, &kname);
+	krb5_free_principal(princ);
+	strncpy(kname_out, kname, sizeof (kname_out));
+	free(kname);
+	return kname_out;
+    }
+#endif
+    if (ha->family == FamilyLocalHost) {
+	return "";
+    }
+    return (NULL);
+}
+
+static signal_t nameserver_lost()
+{
+    nameserver_timedout = 1;
+    longjmp(env, -1);
+}
+
+/*
+ * local_xerror - local non-fatal error handling routine. If the error was
+ * that an X_GetHosts request for an unknown address format was received, just
+ * return, otherwise print the normal error message and continue.
+ */
+static int local_xerror (dpy, rep)
+    Display *dpy;
+    XErrorEvent *rep;
+{
+    if ((rep->error_code == BadAccess) && (rep->request_code == X_ChangeHosts)) {
+	fprintf (stderr, 
+		 "%s:  must be on local machine to add or remove hosts.\n",
+		 ProgramName);
+	return 1;
+    } else if ((rep->error_code == BadAccess) && 
+	       (rep->request_code == X_SetAccessControl)) {
+	fprintf (stderr, 
+	"%s:  must be on local machine to enable or disable access control.\n",
+		 ProgramName);
+	return 1;
+    } else if ((rep->error_code == BadValue) && 
+	       (rep->request_code == X_ListHosts)) {
+	return 1;
+    }
+
+    XmuPrintDefaultErrorMessage (dpy, rep, stderr);
+    return 0;
+}
diff --git a/xhost.man b/xhost.man
new file mode 100644
index 0000000..7bc4359
--- /dev/null
+++ b/xhost.man
@@ -0,0 +1,134 @@
+.\" $Xorg: xhost.man,v 1.4 2001/02/09 02:05:46 xorgcvs Exp $
+.\" Copyright 1988, 1998  The Open Group
+.\" 
+.\" Permission to use, copy, modify, distribute, and sell this software and its
+.\" documentation for any purpose is hereby granted without fee, provided that
+.\" the above copyright notice appear in all copies and that both that
+.\" copyright notice and this permission notice appear in supporting
+.\" documentation.
+.\" 
+.\" The above copyright notice and this permission notice shall be included
+.\" in all copies or substantial portions of the Software.
+.\" 
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
+.\" OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+.\" ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+.\" OTHER DEALINGS IN THE SOFTWARE.
+.\" 
+.\" Except as contained in this notice, the name of The Open Group shall
+.\" not be used in advertising or otherwise to promote the sale, use or
+.\" other dealings in this Software without prior written authorization
+.\" from The Open Group.
+.TH XHOST 1 "Release 6.4" "X Version 11"
+.SH NAME
+xhost \- server access control program for X
+.SH SYNOPSIS
+.B xhost
+[[+\-]name ...]
+.SH DESCRIPTION
+The \fIxhost\fP program 
+is used to add and delete host names or user names to the list allowed
+to make connections to the X server.  In the case of hosts, this provides
+a rudimentary form of privacy control and security.  It is only sufficient
+for a workstation (single user) environment, although it does limit the
+worst abuses.  Environments which require more sophisticated measures should
+implement the user-based mechanism or use the hooks in the
+protocol for passing other authentication data to the server.
+.SH OPTIONS
+\fIXhost\fP accepts the following command line options described below.  For
+security, the options that effect access control may only be run from the
+"controlling host".  For workstations, this is the same machine as the
+server.  For X terminals, it is the login host.
+.TP 8
+.B \-help
+Prints a usage message.
+.TP 8
+.BI "[+]" "name"
+The given \fIname\fP (the plus sign is optional)
+is added to the list allowed to connect to the X server.
+The name can be a host name or a user name.
+.TP 8
+.BI \- "name"
+The given \fIname\fP is removed from the list of allowed
+to connect to the server.  The name can be a host name or a user name.
+Existing connections are not broken, but new
+connection attempts will be denied.
+Note that the current machine is allowed to be removed; however, further
+connections (including attempts to add it back) will not be permitted.
+Resetting the server (thereby breaking all connections) 
+is the only way to allow local connections again.
+.TP 8
+.B \+
+Access is granted to everyone, even if they aren't on the list
+(i.e., access control is turned off).
+.TP 8
+.B \-
+Access is restricted to only those on the list
+(i.e., access control is turned on).
+.TP 8
+.I nothing
+If no command line arguments are given,
+a message indicating whether or not access control is currently enabled
+is printed, followed by the list of those allowed to connect.
+This is the only option that may be used from machines other than
+the controlling host.
+.SH NAMES
+A complete name has the syntax
+``family:name'' where the families are
+as follows:
+.PP
+.nf
+.ta 1i
+inet	Internet host
+dnet	DECnet host
+nis	Secure RPC network name
+krb	Kerberos V5 principal
+local	contains only one name, the empty string
+.fi
+.PP
+The family is case insensitive.
+The format of the name varies with the family.
+.PP
+When Secure RPC is being used, the
+network independent netname (e.g., "nis:unix.\fIuid\fP@\fIdomainname\fP") can
+be specified, or a local user can be specified with just the username
+and a trailing at-sign (e.g., "nis:pat@").
+.PP
+For backward compatibility with pre-R6 \fIxhost\fP,
+names that contain an at-sign (@) are assumed to be in the nis family.
+Otherwise the inet family is assumed.
+.SH DIAGNOSTICS
+For each name added to the access control list,
+a line of the form "\fIname\fP being added to access control list"
+is printed.
+For each name removed from the access control list,
+a line of the form "\fIname\fP being removed from access control list"
+is printed.
+.SH FILES
+/etc/X*.hosts
+.SH "SEE ALSO"
+X(1), Xsecurity(1), Xserver(1), xdm(1)
+.SH ENVIRONMENT
+.TP 8
+.B DISPLAY
+to get the default host and display to use.
+.SH BUGS
+.PP
+You can't specify a display on the command line because
+.B \-display 
+is a valid command line argument (indicating that you want
+to remove the machine named 
+.I ``display''
+from the access list).
+.PP
+The X server stores network addresses, not host names.  This is not
+really a bug.  If somehow you change a host's network address while
+the server is still running, \fIxhost\fP must be used to add the new
+address and/or remove the old address.
+.SH AUTHORS
+Bob Scheifler, MIT Laboratory for Computer Science,
+.br
+Jim Gettys, MIT Project Athena (DEC).