diff --git a/src/backend/libpq/hba.c b/src/backend/libpq/hba.c
index d0734d3ea5..e78569ae2a 100644
--- a/src/backend/libpq/hba.c
+++ b/src/backend/libpq/hba.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/libpq/hba.c,v 1.22 1997/09/08 21:43:45 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/hba.c,v 1.23 1997/11/07 20:51:27 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -855,8 +855,8 @@ authident(const char DataDir[],
 
 	/* The username returned by ident */
 
-	ident(port.raddr.sin_addr, port.laddr.sin_addr,
-		  port.raddr.sin_port, port.laddr.sin_port,
+	ident(port.raddr.in.sin_addr, port.laddr.in.sin_addr,
+		  port.raddr.in.sin_port, port.laddr.in.sin_port,
 		  &ident_failed, ident_username);
 
 	if (ident_failed)
@@ -906,10 +906,13 @@ hba_recvauth(const Port *port, const char database[], const char user[],
 	 */
 	int			retvalue;
 
+	/* UNIX socket always OK, for now */
+	if(port->raddr.in.sin_family == AF_UNIX)
+	  return STATUS_OK;
 	/* Our eventual return value */
+	
 
-
-	find_hba_entry(DataDir, port->raddr.sin_addr, database,
+	find_hba_entry(DataDir, port->raddr.in.sin_addr, database,
 				   &host_ok, &userauth, usermap_name,
 				   false		/* don't find password entries of type
 					   'password' */ );
diff --git a/src/backend/libpq/password.c b/src/backend/libpq/password.c
index aaa204b4db..de803905cb 100644
--- a/src/backend/libpq/password.c
+++ b/src/backend/libpq/password.c
@@ -26,7 +26,7 @@ verify_password(char *user, char *password, Port *port,
 			   *test_pw;
 	char		salt[3];
 
-	find_hba_entry(DataDir, port->raddr.sin_addr, database,
+	find_hba_entry(DataDir, port->raddr.in.sin_addr, database,
 				   &host_ok, &userauth, pw_file_name, true);
 
 	if (!host_ok)
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index 40a9f32c23..a75631e5f0 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/libpq/pqcomm.c,v 1.23 1997/09/18 20:20:39 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/pqcomm.c,v 1.24 1997/11/07 20:51:34 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -571,20 +571,27 @@ pq_async_notify()
  *
  * RETURNS: STATUS_OK or STATUS_ERROR
  */
+
+static char sock_path[100] = "";
+
+static void do_unlink()
+{
+  if (sock_path[0]) unlink(sock_path);
+}
+
 int
 StreamServerPort(char *hostName, short portName, int *fdP)
 {
 	struct sockaddr_in sin;
-	int			fd;
+	struct sockaddr_un sun;
+	int			fd, err, family;
 	int			one = 1;
 
-
-	if (!hostName)
-		hostName = "localhost";
+	family = hostName != NULL ? AF_INET : AF_UNIX;
 
 	MemSet((char *) &sin, 0, sizeof sin);
 
-	if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+	if ((fd = socket(family, SOCK_STREAM, 0)) < 0)
 	{
 		sprintf(PQerrormsg,
 				"FATAL: StreamServerPort: socket() failed: errno=%d\n",
@@ -593,7 +600,7 @@ StreamServerPort(char *hostName, short portName, int *fdP)
 		pqdebug("%s", PQerrormsg);
 		return (STATUS_ERROR);
 	}
-
+	if (family == AF_UNIX) on_exitpg(do_unlink, (caddr_t) 0);
 	if ((setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &one,
 					sizeof(one))) == -1)
 	{
@@ -604,11 +611,24 @@ StreamServerPort(char *hostName, short portName, int *fdP)
 		pqdebug("%s", PQerrormsg);
 		return (STATUS_ERROR);
 	}
-
-	sin.sin_family = AF_INET;
-	sin.sin_port = htons(portName);
-
-	if (bind(fd, (struct sockaddr *) & sin, sizeof sin) < 0)
+	if (family == AF_UNIX)
+	  {
+	    size_t len;
+	    bzero(&sun, sizeof(sun));
+	    sun.sun_family = family;
+	    len = UNIXSOCK_PATH(sun,portName);
+	    strcpy(sock_path, sun.sun_path);
+	    err = bind(fd, (struct sockaddr *) &sun, len);
+	  }
+	else
+	  {
+	    bzero(&sin, sizeof(sin));
+	    sin.sin_family = family;
+	    sin.sin_addr.s_addr = htonl(INADDR_ANY);
+	    sin.sin_port = htons(portName);
+	    err = bind(fd, (struct sockaddr *) &sin, sizeof sin);
+	  }
+	if (err < 0)
 	{
 		sprintf(PQerrormsg,
 				"FATAL: StreamServerPort: bind() failed: errno=%d\n",
@@ -645,26 +665,30 @@ StreamServerPort(char *hostName, short portName, int *fdP)
 int
 StreamConnection(int server_fd, Port *port)
 {
-	int			addrlen;
+	int len, addrlen;
+	int family = port->raddr.in.sin_family;
 
 	/* accept connection (and fill in the client (remote) address) */
-	addrlen = sizeof(struct sockaddr_in);
+	len = family == AF_INET ?
+	  sizeof(struct sockaddr_in) : sizeof(struct sockaddr_un);
+	addrlen = len;
 	if ((port->sock = accept(server_fd,
-							 (struct sockaddr *) & port->raddr,
-							 &addrlen)) < 0)
+				 (struct sockaddr *) & port->raddr,
+				 &addrlen)) < 0)
 	{
 		elog(WARN, "postmaster: StreamConnection: accept: %m");
 		return (STATUS_ERROR);
 	}
-
+	
 	/* fill in the server (local) address */
-	addrlen = sizeof(struct sockaddr_in);
+	addrlen = len;
 	if (getsockname(port->sock, (struct sockaddr *) & port->laddr,
 					&addrlen) < 0)
 	{
 		elog(WARN, "postmaster: StreamConnection: getsockname: %m");
 		return (STATUS_ERROR);
 	}
+	if (family == AF_INET)
 	{
 		struct protoent *pe;
 		int			on = 1;
@@ -714,45 +738,50 @@ StreamClose(int sock)
 int
 StreamOpen(char *hostName, short portName, Port *port)
 {
+        int len, err;
 	struct hostent *hp;
-	int			laddrlen = sizeof(struct sockaddr_in);
 	extern int	errno;
-
-	if (!hostName)
-		hostName = "localhost";
-
+	
 	/* set up the server (remote) address */
-	if (!(hp = gethostbyname(hostName)) || hp->h_addrtype != AF_INET)
-	{
+	MemSet((char *) &port->raddr, 0, sizeof(port->raddr));
+	if (hostName)
+	  {
+	    if (!(hp = gethostbyname(hostName)) || hp->h_addrtype != AF_INET)
+	      {
 		sprintf(PQerrormsg,
-				"FATAL: StreamOpen: unknown hostname: %s\n",
-				hostName);
+			"FATAL: StreamOpen: unknown hostname: %s\n",
+			hostName);
 		fputs(PQerrormsg, stderr);
 		pqdebug("%s", PQerrormsg);
 		return (STATUS_ERROR);
-	}
-	MemSet((char *) &port->raddr, 0, sizeof(port->raddr));
-	memmove((char *) &(port->raddr.sin_addr),
-			(char *) hp->h_addr,
-			hp->h_length);
-	port->raddr.sin_family = AF_INET;
-	port->raddr.sin_port = htons(portName);
-
+	      }
+	    memmove((char *) &(port->raddr.in.sin_addr),
+		    (char *) hp->h_addr,
+		    hp->h_length);
+	    port->raddr.in.sin_family = AF_INET;
+	    port->raddr.in.sin_port = htons(portName);
+	    len = sizeof(struct sockaddr_in);
+	  }
+	else
+	  {
+	    port->raddr.un.sun_family = AF_UNIX;
+	    len  = UNIXSOCK_PATH(port->raddr.un,portName);
+	  }
 	/* connect to the server */
-	if ((port->sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+	if ((port->sock=socket(port->raddr.in.sin_family, SOCK_STREAM, 0)) < 0)
 	{
 		sprintf(PQerrormsg,
-				"FATAL: StreamOpen: socket() failed: errno=%d\n",
+			"FATAL: StreamOpen: socket() failed: errno=%d\n",
 				errno);
 		fputs(PQerrormsg, stderr);
 		pqdebug("%s", PQerrormsg);
 		return (STATUS_ERROR);
 	}
-	if (connect(port->sock, (struct sockaddr *) & port->raddr,
-				sizeof(port->raddr)) < 0)
+	err = connect(port->sock, (struct sockaddr*) &port->raddr, len);
+	if (err < 0)
 	{
 		sprintf(PQerrormsg,
-				"FATAL: StreamOpen: connect() failed: errno=%d\n",
+			"FATAL: StreamOpen: connect() failed: errno=%d\n",
 				errno);
 		fputs(PQerrormsg, stderr);
 		pqdebug("%s", PQerrormsg);
@@ -761,7 +790,7 @@ StreamOpen(char *hostName, short portName, Port *port)
 
 	/* fill in the client address */
 	if (getsockname(port->sock, (struct sockaddr *) & port->laddr,
-					&laddrlen) < 0)
+			&len) < 0)
 	{
 		sprintf(PQerrormsg,
 				"FATAL: StreamOpen: getsockname() failed: errno=%d\n",
diff --git a/src/backend/libpq/pqpacket.c b/src/backend/libpq/pqpacket.c
index 1e95794c85..d699f00d0f 100644
--- a/src/backend/libpq/pqpacket.c
+++ b/src/backend/libpq/pqpacket.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/libpq/Attic/pqpacket.c,v 1.8 1997/09/08 21:43:52 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/libpq/Attic/pqpacket.c,v 1.9 1997/11/07 20:51:36 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -85,7 +85,7 @@ PacketReceive(Port *port,		/* receive port */
 
 	/*
 	 * Assume port->nBytes is zero unless we were interrupted during
-	 * non-blocking I/O.  This first recvfrom() is to get the hdr
+	 * non-blocking I/O.  This first recv() is to get the hdr
 	 * information so we know how many bytes to read.  Life would be very
 	 * complicated if we read too much data (buffering).
 	 */
@@ -98,8 +98,7 @@ PacketReceive(Port *port,		/* receive port */
 	else
 	{
 		/* peeking into the incoming message */
-		cc = recvfrom(port->sock, (char *) &(buf->len), hdrLen, flag,
-					  (struct sockaddr *) & (port->raddr), &addrLen);
+		cc = recv(port->sock, (char *) &(buf->len), hdrLen, flag);
 		if (cc < hdrLen)
 		{
 			/* if cc is negative, the system call failed */
@@ -179,8 +178,7 @@ PacketReceive(Port *port,		/* receive port */
 	 */
 	while (packetLen)
 	{
-		cc = recvfrom(port->sock, tmp, packetLen, 0,
-					  (struct sockaddr *) & (port->raddr), &addrLen);
+		cc = read(port->sock, tmp, packetLen);
 		if (cc < 0)
 			return (STATUS_ERROR);
 
@@ -224,18 +222,13 @@ PacketSend(Port *port,
 		   PacketLen len,
 		   bool nonBlocking)
 {
-	PacketLen	totalLen;
-	int			addrLen = sizeof(struct sockaddr_in);
+	PacketLen	doneLen;
 
 	Assert(!nonBlocking);
 	Assert(buf);
 
-	totalLen = len;
-
-	len = sendto(port->sock, (Addr) buf, totalLen, /* flags */ 0,
-				 (struct sockaddr *) & (port->raddr), addrLen);
-
-	if (len < totalLen)
+	doneLen = write(port->sock,  buf, len);
+	if (doneLen < len)
 	{
 		sprintf(PQerrormsg,
 		  "FATAL: PacketSend: couldn't send complete packet: errno=%d\n",
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index a936fff9eb..2eef75ca5e 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.59 1997/10/25 01:09:55 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.60 1997/11/07 20:51:47 momjian Exp $
  *
  * NOTES
  *
@@ -131,7 +131,8 @@ static char *progname = (char *) NULL;
  */
 static char Execfile[MAXPATHLEN] = "";
 
-static int	ServerSock = INVALID_SOCK;	/* stream socket server */
+static int ServerSock_INET = INVALID_SOCK;	/* stream socket server */
+static int ServerSock_UNIX = INVALID_SOCK;	/* stream socket server */
 
 /*
  * Set by the -o option
@@ -148,6 +149,8 @@ static char ExtraOptions[ARGV_SIZE] = "";
 static int	Reinit = 1;
 static int	SendStop = 0;
 
+static int      NetServer = 0; /* if not zero, postmaster listen for
+				  non-local connections */
 static int	MultiplexedBackends = 0;
 static int	MultiplexedBackendPort;
 
@@ -244,8 +247,8 @@ PostmasterMain(int argc, char *argv[])
 	char	   *hostName;
 	int			status;
 	int			silentflag = 0;
-	char		hostbuf[MAXHOSTNAMELEN];
 	bool		DataDirOK;		/* We have a usable PGDATA value */
+	char		hostbuf[MAXHOSTNAMELEN];
 
 	progname = argv[0];
 
@@ -267,7 +270,7 @@ PostmasterMain(int argc, char *argv[])
 	DataDir = getenv("PGDATA"); /* default value */
 
 	opterr = 0;
-	while ((opt = getopt(argc, argv, "a:B:b:D:dm:Mno:p:Ss")) != EOF)
+	while ((opt = getopt(argc, argv, "a:B:b:D:dim:Mno:p:Ss")) != EOF)
 	{
 		switch (opt)
 		{
@@ -315,6 +318,9 @@ PostmasterMain(int argc, char *argv[])
 				else
 					DebugLvl = 1;
 				break;
+		        case 'i':
+			        NetServer = 1;
+				break;
 			case 'm':
 				MultiplexedBackends = 1;
 				MultiplexedBackendPort = atoi(optarg);
@@ -387,11 +393,20 @@ PostmasterMain(int argc, char *argv[])
 		exit(1);
 	}
 
-
-	status = StreamServerPort(hostName, PostPortName, &ServerSock);
+	if (NetServer)
+	  {
+	    status = StreamServerPort(hostName, PostPortName, &ServerSock_INET);
+	    if (status != STATUS_OK)
+	      {
+		fprintf(stderr, "%s: cannot create INET stream port\n",
+			progname);
+		exit(1);
+	      }
+	  }
+	status = StreamServerPort(NULL, PostPortName, &ServerSock_UNIX);
 	if (status != STATUS_OK)
 	{
-		fprintf(stderr, "%s: cannot create stream port\n",
+		fprintf(stderr, "%s: cannot create UNIX stream port\n",
 				progname);
 		exit(1);
 	}
@@ -459,6 +474,7 @@ usage(const char *progname)
 	fprintf(stderr, "\t-b backend\tuse a specific backend server executable\n");
 	fprintf(stderr, "\t-d [1|2|3]\tset debugging level\n");
 	fprintf(stderr, "\t-D datadir\tset data directory\n");
+	fprintf(stderr, "\t-i \tlisten on TCP/IP sockets as well as Unix domain socket\n");
 	fprintf(stderr, "\t-m \tstart up multiplexing backends\n");
 	fprintf(stderr, "\t-n\t\tdon't reinitialize shared memory after abnormal exit\n");
 	fprintf(stderr, "\t-o option\tpass 'option' to each backend servers\n");
@@ -471,13 +487,11 @@ usage(const char *progname)
 static int
 ServerLoop(void)
 {
-	int			serverFd = ServerSock;
-	fd_set		rmask,
-				basemask;
+	fd_set		rmask, basemask;
 	int			nSockets,
 				nSelected,
 				status,
-				newFd;
+				oldFd, newFd;
 	Dlelem	   *next,
 			   *curr;
 
@@ -493,10 +507,16 @@ ServerLoop(void)
 	int			orgsigmask = sigblock(0);
 
 #endif
-
-	nSockets = ServerSock + 1;
 	FD_ZERO(&basemask);
-	FD_SET(ServerSock, &basemask);
+	FD_SET(ServerSock_UNIX, &basemask);
+	nSockets = ServerSock_UNIX;
+	if (ServerSock_INET != INVALID_SOCK)
+	  {
+	    FD_SET(ServerSock_INET, &basemask);
+	    if (ServerSock_INET > ServerSock_UNIX) 
+	      nSockets = ServerSock_INET;
+	  }
+	nSockets++;
 
 #ifdef HAVE_SIGPROCMASK
 	sigprocmask(0, 0, &oldsigmask);
@@ -542,15 +562,21 @@ ServerLoop(void)
 		}
 
 		/* new connection pending on our well-known port's socket */
-		if (FD_ISSET(ServerSock, &rmask))
+		oldFd = -1;
+		if (FD_ISSET(ServerSock_UNIX, &rmask)) 
+		  oldFd = ServerSock_UNIX;
+		else if (ServerSock_INET != INVALID_SOCK && 
+			 FD_ISSET(ServerSock_INET, &rmask))
+		  oldFd = ServerSock_INET;
+		if (oldFd >= 0)
 		{
-
+		  
 			/*
 			 * connect and make an addition to PortList.  If the
 			 * connection dies and we notice it, just forget about the
 			 * whole thing.
 			 */
-			if (ConnCreate(serverFd, &newFd) == STATUS_OK)
+			if (ConnCreate(oldFd, &newFd) == STATUS_OK)
 			{
 				if (newFd >= nSockets)
 					nSockets = newFd + 1;
@@ -560,8 +586,12 @@ ServerLoop(void)
 					fprintf(stderr, "%s: ServerLoop: connect on %d\n",
 							progname, newFd);
 			}
+			else if (DebugLvl)
+			  fprintf(stderr, 
+				  "%s: ServerLoop: connect failed: (%d) %s\n",
+				  progname, errno, strerror(errno));
 			--nSelected;
-			FD_CLR(ServerSock, &rmask);
+			FD_CLR(oldFd, &rmask);
 		}
 
 		if (DebugLvl > 1)
@@ -793,7 +823,7 @@ ConnStartup(Port *port, int *status,
 static void
 send_error_reply(Port *port, const char *errormsg)
 {
-	int			rc;				/* return code from sendto */
+	int			rc;	/* return code from write */
 	char	   *reply;
 
 	/*
@@ -812,7 +842,7 @@ send_error_reply(Port *port, const char *errormsg)
 
 	sprintf(reply, "E%s", errormsg);
 
-	rc = send(port->sock, (Addr) reply, strlen(reply) + 1, /* flags */ 0);
+	rc = write(port->sock, (Addr) reply, strlen(reply) + 1);
 	if (rc < 0)
 		fprintf(stderr,
 				"%s: ServerLoop:\t\t"
@@ -1269,8 +1299,8 @@ ExitPostmaster(int status)
 	 * Not sure of the semantics here.	When the Postmaster dies, should
 	 * the backends all be killed? probably not.
 	 */
-	if (ServerSock != INVALID_SOCK)
-		close(ServerSock);
+	if (ServerSock_INET != INVALID_SOCK) close(ServerSock_INET);
+	if (ServerSock_UNIX != INVALID_SOCK) close(ServerSock_UNIX);
 	exitpg(status);
 }
 
@@ -1285,9 +1315,10 @@ dumpstatus(SIGNAL_ARGS)
 
 		fprintf(stderr, "%s: dumpstatus:\n", progname);
 		fprintf(stderr, "\tsock %d: nBytes=%d, laddr=0x%lx, raddr=0x%lx\n",
-				port->sock, port->nBytes,
-				(long int) port->laddr.sin_addr.s_addr,
-				(long int) port->raddr.sin_addr.s_addr);
+			port->sock, port->nBytes,
+			(long int) port->laddr.in.sin_addr.s_addr,
+			(long int) port->raddr.in.sin_addr.s_addr);
 		curr = DLGetSucc(curr);
 	}
 }
+
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 8654c11ad8..729f9a0003 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.51 1997/11/02 15:25:45 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.52 1997/11/07 20:51:54 momjian Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -832,7 +832,6 @@ PostgresMain(int argc, char *argv[])
 
 	bool		multiplexedBackend;
 	char	   *hostName;		/* the host name of the backend server */
-	char		hostbuf[MAXHOSTNAMELEN];
 	int			serverSock;
 	int			serverPortnum = 0;
 	int			nSelected;		/* number of descriptors ready from
@@ -884,15 +883,10 @@ PostgresMain(int argc, char *argv[])
 #endif
 
 	/*
-	 * get hostname is either the environment variable PGHOST or
-	 * 'localhost'
+	 * get hostname is either the environment variable PGHOST or NULL
+	 * NULL means Unix-socket only
 	 */
-	if (!(hostName = getenv("PGHOST")))
-	{
-		if (gethostname(hostbuf, MAXHOSTNAMELEN) < 0)
-			strcpy(hostbuf, "localhost");
-		hostName = hostbuf;
-	}
+	hostName = getenv("PGHOST");
 
 	DataDir = getenv("PGDATA"); /* default */
 	multiplexedBackend = false; /* default */
@@ -1252,7 +1246,7 @@ PostgresMain(int argc, char *argv[])
 	if (multiplexedBackend)
 	{
 		if (serverPortnum == 0 ||
-			StreamServerPort(hostName, serverPortnum, &serverSock) != STATUS_OK)
+		    StreamServerPort(hostName, serverPortnum, &serverSock) != STATUS_OK)
 		{
 			fprintf(stderr, "Postgres: cannot create stream port %d\n", serverPortnum);
 			exit(1);
@@ -1343,7 +1337,7 @@ PostgresMain(int argc, char *argv[])
 	if (IsUnderPostmaster == false)
 	{
 		puts("\nPOSTGRES backend interactive interface");
-		puts("$Revision: 1.51 $ $Date: 1997/11/02 15:25:45 $");
+		puts("$Revision: 1.52 $ $Date: 1997/11/07 20:51:54 $");
 	}
 
 	/* ----------------
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index a6e670e5f6..1589c83dce 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.15 1997/11/07 06:38:46 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.16 1997/11/07 20:51:58 momjian Exp $
  *
  * NOTES
  *		InitPostgres() is the function called from PostgresMain
@@ -310,9 +310,6 @@ InitCommunication()
 	{
 		SystemPortAddress address = atoi(postport);
 
-		if (address == 0)
-			elog(FATAL, "InitCommunication: invalid POSTPORT");
-
 		if (MyBackendTag == -1)
 			elog(FATAL, "InitCommunication: missing POSTID");
 
diff --git a/src/include/libpq/pqcomm.h b/src/include/libpq/pqcomm.h
index 65892b8a81..399e3231b6 100644
--- a/src/include/libpq/pqcomm.h
+++ b/src/include/libpq/pqcomm.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pqcomm.h,v 1.15 1997/09/12 22:26:13 momjian Exp $
+ * $Id: pqcomm.h,v 1.16 1997/11/07 20:52:06 momjian Exp $
  *
  * NOTES
  *	  Some of this should move to libpq.h
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <netinet/in.h>
+#include <sys/un.h>
 
 
 /*
@@ -27,6 +28,10 @@
 #define PATH_SIZE		64
 #define ARGV_SIZE		64
 
+#define UNIXSOCK_PATH(sun,port) \
+  sprintf(sun.sun_path,"/tmp/.s.PGSQL.%d",port) + sizeof(sun.sun_family) + 1;
+
+
 /* The various kinds of startup messages are for the various kinds of
    user authentication systems.  In the beginning, there was only
    STARTUP_MSG and all connections were unauthenticated.  Now, there are
@@ -106,9 +111,10 @@ typedef struct Port
 	int			sock;			/* file descriptor */
 	int			mask;			/* select mask */
 	int			nBytes;			/* nBytes read in so far */
-	struct sockaddr_in laddr;	/* local addr (us) */
-	struct sockaddr_in raddr;	/* remote addr (them) */
-
+	/* local addr (us) */
+        union {  struct sockaddr_in in; struct sockaddr_un un; } laddr;
+        /* remote addr (them) */
+        union {  struct sockaddr_in in; struct sockaddr_un un; }  raddr;
 	/*
 	 * PacketBufId				id;
 *//* id of packet buf currently in use */
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 942082b0d0..f5ace69dc0 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v 1.42 1997/09/18 20:22:46 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-connect.c,v 1.43 1997/11/07 20:52:15 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,7 +86,7 @@ static PQconninfoOption PQconninfoOptions[] = {
 	{"dbname", "PGDATABASE", NULL, NULL,
 	"Database-Name", "", 20},
 
-	{"host", "PGHOST", DefaultHost, NULL,
+	{"host", "PGHOST", NULL, NULL,
 	"Database-Host", "", 40},
 
 	{"port", "PGPORT", DEF_PGPORT, NULL,
@@ -340,11 +340,8 @@ PQsetdb(const char *pghost, const char *pgport, const char *pgoptions, const cha
 
 		if (!pghost || pghost[0] == '\0')
 		{
-			if (!(tmp = getenv("PGHOST")))
-			{
-				tmp = DefaultHost;
-			}
-			conn->pghost = strdup(tmp);
+		  conn->pghost = NULL;
+		  if (tmp = getenv("PGHOST")) conn->pghost = strdup(tmp);
 		}
 		else
 			conn->pghost = strdup(pghost);
@@ -473,7 +470,7 @@ connectDB(PGconn *conn)
 	MsgType		msgtype;
 	int			laddrlen = sizeof(struct sockaddr);
 	Port	   *port = conn->port;
-	int			portno;
+	int			portno, family, len;
 
 	/*
 	 * Initialize the startup packet.
@@ -501,7 +498,8 @@ connectDB(PGconn *conn)
 	port = (Port *) malloc(sizeof(Port));
 	MemSet((char *) port, 0, sizeof(Port));
 
-	if (!(hp = gethostbyname(conn->pghost)) || hp->h_addrtype != AF_INET)
+	if (conn->pghost && 
+	    (!(hp = gethostbyname(conn->pghost)) || hp->h_addrtype != AF_INET))
 	{
 		(void) sprintf(conn->errorMessage,
 					   "connectDB() --  unknown hostname: %s\n",
@@ -509,29 +507,37 @@ connectDB(PGconn *conn)
 		goto connect_errReturn;
 	}
 	MemSet((char *) &port->raddr, 0, sizeof(port->raddr));
-	memmove((char *) &(port->raddr.sin_addr),
-			(char *) hp->h_addr,
-			hp->h_length);
-	port->raddr.sin_family = AF_INET;
 	portno = atoi(conn->pgport);
-	port->raddr.sin_port = htons((unsigned short) (portno));
-
+	port->raddr.in.sin_family = family = conn->pghost ? AF_INET : AF_UNIX;
+	if (family == AF_INET)
+	  {
+	    memmove((char *) &(port->raddr.in.sin_addr),
+		    (char *) hp->h_addr,
+		    hp->h_length);
+	    port->raddr.in.sin_port = htons((unsigned short) (portno));
+	    len = sizeof(struct sockaddr_in);
+	  }
+	else
+	  {
+	    len = UNIXSOCK_PATH(port->raddr.un,portno);
+	  }
 	/* connect to the server  */
-	if ((port->sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+	if ((port->sock = socket(family, SOCK_STREAM, 0)) < 0)
 	{
 		(void) sprintf(conn->errorMessage,
 					   "connectDB() -- socket() failed: errno=%d\n%s\n",
 					   errno, strerror(errno));
 		goto connect_errReturn;
 	}
-	if (connect(port->sock, (struct sockaddr *) & port->raddr,
-				sizeof(port->raddr)) < 0)
+	if (connect(port->sock, (struct sockaddr *) &port->raddr, len) < 0)
 	{
 		(void) sprintf(conn->errorMessage,
-					   "connectDB() failed: Is the postmaster running at '%s' on port '%s'?\n",
-					   conn->pghost, conn->pgport);
+			       "connectDB() failed: Is the postmaster running at '%s' on port '%s'?\n",
+			       conn->pghost ? conn->pghost : "UNIX Socket", 
+			       conn->pgport);
 		goto connect_errReturn;
 	}
+	if (family == AF_INET)
 	{
 		struct protoent *pe;
 		int			on = 1;
@@ -773,19 +779,11 @@ packetSend(Port *port,
 		   PacketLen len,
 		   bool nonBlocking)
 {
-	PacketLen	totalLen;
-	int			addrLen = sizeof(struct sockaddr_in);
-
-	totalLen = len;
-
-	len = sendto(port->sock, (Addr) buf, totalLen, /* flags */ 0,
-				 (struct sockaddr *) & (port->raddr), addrLen);
-
-	if (len < totalLen)
+	PacketLen doneLen = write(port->sock,  buf, len);
+	if (doneLen < len)
 	{
 		return (STATUS_ERROR);
 	}
-
 	return (STATUS_OK);
 }