diff --git a/stand/libsa/close.c b/stand/libsa/close.c
--- a/stand/libsa/close.c
+++ b/stand/libsa/close.c
@@ -68,23 +68,38 @@
 int
 close(int fd)
 {
-	struct open_file *f = &files[fd];
+	struct open_file *f, *last;
 	int err1 = 0, err2 = 0;
 
-	if ((unsigned)fd >= SOPEN_MAX || f->f_flags == 0) {
+	f = fd2open_file(fd);
+	if (f == NULL) {
 		errno = EBADF;
 		return (-1);
 	}
 	free(f->f_rabuf);
 	f->f_rabuf = NULL;
 
-	if (!(f->f_flags & F_RAW) && f->f_ops)
-		err1 = (f->f_ops->fo_close)(f);
-	if (!(f->f_flags & F_NODEV) && f->f_dev)
-		err2 = (f->f_dev->dv_close)(f);
-	if (f->f_devdata != NULL)
-		devclose(f);
-	f->f_flags = 0;
+	if (f->f_flags != 0) {
+		if (!(f->f_flags & F_RAW) && f->f_ops)
+			err1 = (f->f_ops->fo_close)(f);
+		if (!(f->f_flags & F_NODEV) && f->f_dev)
+			err2 = (f->f_dev->dv_close)(f);
+		if (f->f_devdata != NULL)
+			devclose(f);
+		f->f_flags = 0;
+	} else {
+		/* Attempt to close already closed file. */
+		err1 = EBADF;
+	}
+
+	/* free unused entries from tail. */
+	TAILQ_FOREACH_REVERSE_SAFE(last, &files, file_list, f_link, f) {
+		if (last->f_flags != 0)
+			break;
+		TAILQ_REMOVE(&files, last, f_link);
+		free(last);
+	}
+
 	if (err1) {
 		errno = err1;
 		return (-1);
diff --git a/stand/libsa/closeall.c b/stand/libsa/closeall.c
--- a/stand/libsa/closeall.c
+++ b/stand/libsa/closeall.c
@@ -1,11 +1,7 @@
-/*	$NetBSD: closeall.c,v 1.1 1996/01/13 22:25:36 leo Exp $	*/
-
 /*-
- * Copyright (c) 1993
- *	The Regents of the University of California.  All rights reserved.
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
- * This code is derived from software contributed to Berkeley by
- * The Mach Operating System project at Carnegie-Mellon University.
+ * Copyright (c) 2021 Toomas Soome <tsoome@me.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -15,14 +11,11 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
@@ -31,33 +24,6 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)close.c	8.1 (Berkeley) 6/11/93
- *  
- *
- * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
- * All Rights Reserved.
- *
- * Author: Alessandro Forin
- * 
- * Permission to use, copy, modify and distribute this software and its
- * documentation is hereby granted, provided that both the copyright
- * notice and this permission notice appear in all copies of the
- * software, derivative works or modified versions, and any portions
- * thereof, and that both notices appear in supporting documentation.
- * 
- * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
- * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
- * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
- * 
- * Carnegie Mellon requests users of this software to return to
- * 
- *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
- *  School of Computer Science
- *  Carnegie Mellon University
- *  Pittsburgh PA 15213-3890
- * 
- * any improvements or extensions that they make and grant Carnegie the
- * rights to redistribute these changes.
  */
 
 #include <sys/cdefs.h>
@@ -66,11 +32,17 @@
 #include "stand.h"
 
 void
-closeall()
+closeall(void)
 {
-	int i;
+	struct open_file *f;
 
-        for (i = 0; i < SOPEN_MAX; i++)
-            if (files[i].f_flags != 0)
-                (void)close(i);
+	/*
+	 * Pick up last entry and close it, this will also trigger
+	 * the removal of this entry, and we end up with empty list.
+	 */
+	while ((f = TAILQ_LAST(&files, file_list)) != NULL) {
+		(void)close(f->f_id);
+	}
+	/* reset errno from close() */
+	errno = 0;
 }
diff --git a/stand/libsa/fstat.c b/stand/libsa/fstat.c
--- a/stand/libsa/fstat.c
+++ b/stand/libsa/fstat.c
@@ -37,13 +37,12 @@
 #include "stand.h"
 
 int
-fstat(fd, sb)
-	int fd;
-	struct stat *sb;
+fstat(int fd, struct stat *sb)
 {
-	struct open_file *f = &files[fd];
+	struct open_file *f;
 
-	if ((unsigned)fd >= SOPEN_MAX || f->f_flags == 0) {
+	f = fd2open_file(fd);
+	if (f == NULL || f->f_flags == 0) {
 		errno = EBADF;
 		return (-1);
 	}
diff --git a/stand/libsa/ioctl.c b/stand/libsa/ioctl.c
--- a/stand/libsa/ioctl.c
+++ b/stand/libsa/ioctl.c
@@ -32,30 +32,30 @@
  * SUCH DAMAGE.
  *
  *	@(#)ioctl.c	8.1 (Berkeley) 6/11/93
- *  
+ *
  *
  * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
  * All Rights Reserved.
  *
  * Author: Alessandro Forin
- * 
+ *
  * Permission to use, copy, modify and distribute this software and its
  * documentation is hereby granted, provided that both the copyright
  * notice and this permission notice appear in all copies of the
  * software, derivative works or modified versions, and any portions
  * thereof, and that both notices appear in supporting documentation.
- * 
+ *
  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
- * 
+ *
  * Carnegie Mellon requests users of this software to return to
- * 
+ *
  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  *  School of Computer Science
  *  Carnegie Mellon University
  *  Pittsburgh PA 15213-3890
- * 
+ *
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  */
@@ -66,14 +66,12 @@
 #include "stand.h"
 
 int
-ioctl(fd, cmd, arg)
-	int fd;
-	u_long cmd;
-	char *arg;
+ioctl(int fd, u_long cmd, char *arg)
 {
-	struct open_file *f = &files[fd];
+	struct open_file *f;
 
-	if ((unsigned)fd >= SOPEN_MAX || f->f_flags == 0) {
+	f = fd2open_file(fd);
+	if (f == NULL || f->f_flags == 0) {
 		errno = EBADF;
 		return (-1);
 	}
diff --git a/stand/libsa/iodesc.h b/stand/libsa/iodesc.h
--- a/stand/libsa/iodesc.h
+++ b/stand/libsa/iodesc.h
@@ -47,6 +47,8 @@
 	u_long	xid;			/* transaction identification */
 	u_char	myea[6];		/* my ethernet address */
 	struct netif *io_netif;
+	int io_id;			/* descriptor id */
+	TAILQ_ENTRY(iodesc) io_link;	/* next entry in list */
 };
 
 #endif /* __SYS_LIBNETBOOT_IODESC_H */
diff --git a/stand/libsa/lseek.c b/stand/libsa/lseek.c
--- a/stand/libsa/lseek.c
+++ b/stand/libsa/lseek.c
@@ -69,9 +69,10 @@
 lseek(int fd, off_t offset, int where)
 {
 	off_t bufpos, filepos, target;
-	struct open_file *f = &files[fd];
+	struct open_file *f;
 
-	if ((unsigned)fd >= SOPEN_MAX || f->f_flags == 0) {
+	f = fd2open_file(fd);
+	if (f == NULL || f->f_flags == 0) {
 		errno = EBADF;
 		return (-1);
 	}
diff --git a/stand/libsa/net.h b/stand/libsa/net.h
--- a/stand/libsa/net.h
+++ b/stand/libsa/net.h
@@ -97,8 +97,6 @@
 
 extern	int debug;			/* defined in the machdep sources */
 
-extern struct iodesc sockets[SOPEN_MAX];
-
 /* ARP/RevARP functions: */
 u_char	*arpwhohas(struct iodesc *, struct in_addr);
 void	arp_reply(struct iodesc *, void *);
diff --git a/stand/libsa/netif.c b/stand/libsa/netif.c
--- a/stand/libsa/netif.c
+++ b/stand/libsa/netif.c
@@ -47,7 +47,19 @@
 #include "net.h"
 #include "netif.h"
 
-struct iodesc sockets[SOPEN_MAX];
+typedef TAILQ_HEAD(socket_list, iodesc) socket_list_t;
+
+/*
+ * Open socket list. The current implementation and assumption is,
+ * we only remove entries from tail and we only add new entries to tail.
+ * This decision is to keep iodesc id management simple - we get list
+ * entries ordered by continiously growing io_id field.
+ * If we do have multiple sockets open and we do close socket not from tail,
+ * this entry will be marked unused. netif_open() will reuse unused entry, or
+ * netif_close() will free all unused tail entries.
+ */
+static socket_list_t sockets = TAILQ_HEAD_INITIALIZER(sockets);
+
 #ifdef NETIF_DEBUG
 int netif_debug = 0;
 #endif
@@ -63,7 +75,7 @@
 {
 	struct netif_driver *drv;
 	int d, i;
-    
+
 #ifdef NETIF_DEBUG
 	if (netif_debug)
 		printf("netif_init: called\n");
@@ -108,7 +120,7 @@
 		for (u = 0; u < drv->netif_nifs; u++) {
 			cur_if.nif_unit = u;
 			unit_done = 0;
-		
+
 #ifdef NETIF_DEBUG
 			if (netif_debug)
 				printf("\t%s%d:", drv->netif_bname,
@@ -179,14 +191,14 @@
 	if (netif_debug)
 		printf("%s%d: netif_attach\n", drv->netif_bname, nif->nif_unit);
 #endif
-	desc->io_netif = nif; 
+	desc->io_netif = nif;
 #ifdef PARANOID
 	if (drv->netif_init == NULL)
 		panic("%s%d: no netif_init support", drv->netif_bname,
 		    nif->nif_unit);
 #endif
 	drv->netif_init(desc, machdep_hint);
-	bzero(drv->netif_ifs[nif->nif_unit].dif_stats, 
+	bzero(drv->netif_ifs[nif->nif_unit].dif_stats,
 	    sizeof(struct netif_stats));
 }
 
@@ -261,35 +273,71 @@
 	return (rv);
 }
 
+/*
+ * socktodesc_impl:
+ *
+ * Walk socket list and return pointer to iodesc structure.
+ * if id is < 0, return first unused iodesc.
+ */
+static struct iodesc *
+socktodesc_impl(int socket)
+{
+	struct iodesc *s;
+
+	TAILQ_FOREACH(s, &sockets, io_link) {
+		/* search by socket id */
+		if (socket >= 0) {
+			if (s->io_id == socket)
+				break;
+			continue;
+		}
+		/* search for first unused entry */
+		if (s->io_netif == NULL)
+			break;
+	}
+	return (s);
+}
+
 struct iodesc *
 socktodesc(int sock)
 {
-	if (sock >= SOPEN_MAX) {
+	struct iodesc *desc;
+
+	if (sock < 0)
+		desc = NULL;
+	else
+		desc = socktodesc_impl(sock);
+
+	if (desc == NULL)
 		errno = EBADF;
-		return (NULL);
-	}
-	return (&sockets[sock]);
+
+	return (desc);
 }
 
 int
 netif_open(void *machdep_hint)
 {
-	int fd;
 	struct iodesc *s;
 	struct netif *nif;
-	
+
 	/* find a free socket */
-	for (fd = 0, s = sockets; fd < SOPEN_MAX; fd++, s++)
-		if (s->io_netif == (struct netif *)0)
-			goto fnd;
-	errno = EMFILE;
-	return (-1);
-
-fnd:
-	bzero(s, sizeof(*s));
+	s = socktodesc_impl(-1);
+	if (s == NULL) {
+		struct iodesc *last;
+
+		s = calloc(1, sizeof (*s));
+		if (s == NULL)
+			return (-1);
+
+		last = TAILQ_LAST(&sockets, socket_list);
+		if (last != NULL)
+			s->io_id = last->io_id + 1;
+		TAILQ_INSERT_TAIL(&sockets, s, io_link);
+	}
+
 	netif_init();
 	nif = netif_select(machdep_hint);
-	if (!nif) 
+	if (!nif)
 		panic("netboot: no interfaces left untried");
 	if (netif_probe(nif, machdep_hint)) {
 		printf("netboot: couldn't probe %s%d\n",
@@ -299,18 +347,42 @@
 	}
 	netif_attach(nif, s, machdep_hint);
 
-	return (fd);
+	return (s->io_id);
 }
 
 int
 netif_close(int sock)
 {
-	if (sock >= SOPEN_MAX) {
-		errno = EBADF;
+	struct iodesc *s, *last;
+	int err;
+
+	err = 0;
+	s = socktodesc_impl(sock);
+	if (s == NULL || sock < 0) {
+		err = EBADF;
+		return (-1);
+	}
+	netif_detach(s->io_netif);
+	bzero(&s->destip, sizeof (s->destip));
+	bzero(&s->myip, sizeof (s->myip));
+	s->destport = 0;
+	s->myport = 0;
+	s->xid = 0;
+	bzero(s->myea, sizeof (s->myea));
+	s->io_netif = NULL;
+
+	/* free unused entries from tail. */
+	TAILQ_FOREACH_REVERSE_SAFE(last, &sockets, socket_list, io_link, s) {
+		if (last->io_netif != NULL)
+			break;
+		TAILQ_REMOVE(&sockets, last, io_link);
+		free(last);
+	}
+
+	if (err) {
+		errno = err;
 		return (-1);
 	}
-	netif_detach(sockets[sock].io_netif);
-	sockets[sock].io_netif = (struct netif *)0;
 
 	return (0);
 }
diff --git a/stand/libsa/open.c b/stand/libsa/open.c
--- a/stand/libsa/open.c
+++ b/stand/libsa/open.c
@@ -67,17 +67,66 @@
 
 struct fs_ops *exclusive_file_system;
 
-struct open_file files[SOPEN_MAX];
+/*
+ * Open file list. The current implementation and assumption is,
+ * we only remove entries from tail and we only add new entries to tail.
+ * This decision is to keep file id management simple - we get list
+ * entries ordered by continiously growing f_id field.
+ * If we do have multiple files open and we do close file not from tail,
+ * this entry will be marked unused. open() will reuse unused entry, or
+ * close will free all unused tail entries.
+ *
+ * Only case we expect open file list to grow long, is with zfs pools with
+ * many disks. 
+ */
+file_list_t files = TAILQ_HEAD_INITIALIZER(files);
+
+/*
+ * Walk file list and return pointer to open_file structure.
+ * if fd is < 0, return first unused open_file.
+ */
+struct open_file *
+fd2open_file(int fd)
+{
+	struct open_file *f;
+
+	TAILQ_FOREACH(f, &files, f_link) {
+		if (fd >= 0) {
+			if (f->f_id == fd)
+				break;
+			continue;
+		}
+
+		if (f->f_flags == 0)
+			break;
+	}
+	return (f);
+}
 
 static int
-o_gethandle(void)
+o_gethandle(struct open_file **ptr)
 {
-	int fd;
+	struct open_file *f, *last;
 
-	for (fd = 0; fd < SOPEN_MAX; fd++)
-		if (files[fd].f_flags == 0)
-			return (fd);
-	return (-1);
+	/* Pick up unused entry */
+	f = fd2open_file(-1);
+	if (f != NULL) {
+		*ptr = f;
+		return (f->f_id);
+	}
+
+	/* Add new entry */
+	f = calloc(1, sizeof (*f));
+	if (f == NULL)
+		return (-1);
+
+	last = TAILQ_LAST(&files, file_list);
+	if (last != NULL)
+		f->f_id = last->f_id + 1;
+	TAILQ_INSERT_TAIL(&files, f, f_link);
+
+	*ptr = f;
+	return (f->f_id);
 }
 
 static void
@@ -98,12 +147,11 @@
 
 	TSENTER();
 
-	if ((fd = o_gethandle()) == -1) {
+	if ((fd = o_gethandle(&f)) == -1) {
 		errno = EMFILE;
 		return (-1);
 	}
 
-	f = &files[fd];
 	f->f_flags = mode + 1;
 	f->f_dev = NULL;
 	f->f_ops = NULL;
diff --git a/stand/libsa/read.c b/stand/libsa/read.c
--- a/stand/libsa/read.c
+++ b/stand/libsa/read.c
@@ -69,12 +69,13 @@
 ssize_t
 read(int fd, void *dest, size_t bcount)
 {
-	struct open_file *f = &files[fd];
+	struct open_file *f;
 	size_t resid;
 
 	TSENTER();
 
-	if ((unsigned)fd >= SOPEN_MAX || !(f->f_flags & F_READ)) {
+	f = fd2open_file(fd);
+	if (f == NULL || !(f->f_flags & F_READ)) {
 		errno = EBADF;
 		return (-1);
 	}
diff --git a/stand/libsa/readdir.c b/stand/libsa/readdir.c
--- a/stand/libsa/readdir.c
+++ b/stand/libsa/readdir.c
@@ -34,9 +34,10 @@
 readdirfd(int fd)
 {
 	static struct dirent dir;		/* XXX not thread safe */
-	struct open_file *f = &files[fd];
+	struct open_file *f;
 
-	if ((unsigned)fd >= SOPEN_MAX || !(f->f_flags & F_READ)) {
+	f = fd2open_file(fd);
+	if (f == NULL || !(f->f_flags & F_READ)) {
 		errno = EBADF;
 		return (NULL);
 	}
diff --git a/stand/libsa/stand.h b/stand/libsa/stand.h
--- a/stand/libsa/stand.h
+++ b/stand/libsa/stand.h
@@ -65,6 +65,7 @@
 #include <sys/cdefs.h>
 #include <sys/stat.h>
 #include <sys/dirent.h>
+#include <sys/queue.h>
 
 /* this header intentionally exports NULL from <string.h> */
 #include <string.h>
@@ -182,11 +183,14 @@
     char		*f_rabuf;	/* readahead buffer pointer */
     size_t		f_ralen;	/* valid data in readahead buffer */
     off_t		f_raoffset;	/* consumer offset in readahead buffer */
+    int			f_id;		/* file number */
+    TAILQ_ENTRY(open_file) f_link;	/* next entry */
 #define SOPEN_RASIZE	512
 };
 
-#define	SOPEN_MAX	64
-extern struct open_file files[];
+typedef TAILQ_HEAD(file_list, open_file) file_list_t;
+extern file_list_t files;
+extern struct open_file *fd2open_file(int);
 
 /* f_flags values */
 #define	F_READ		0x0001	/* file opened for reading */
diff --git a/stand/libsa/write.c b/stand/libsa/write.c
--- a/stand/libsa/write.c
+++ b/stand/libsa/write.c
@@ -69,10 +69,11 @@
 ssize_t
 write(int fd, const void *dest, size_t bcount)
 {
-	struct open_file *f = &files[fd];
+	struct open_file *f;
 	size_t resid;
 
-	if ((unsigned)fd >= SOPEN_MAX || !(f->f_flags & F_WRITE)) {
+	f = fd2open_file(fd);
+	if (f == NULL || !(f->f_flags & F_WRITE)) {
 		errno = EBADF;
 		return (-1);
 	}