Switch the default NFS mount mode from UDP to TCP. UDP mounts are a

historical relic, and are no longer appropriate for either LAN or WAN
mounting.  At modern (gigabit and 10 gigabit) LAN speeds packet loss
from socket buffer fill events is common, and sequence numbers wrap
quickly enough that data corruption is possible.  TCP solves both of
these problems without imposing significant overhead.

MFC after:     1 month

2 files changed, 6 insertions, 6 deletions

diff --git a/sbin/mount_nfs/mount_nfs.8 b/sbin/mount_nfs/mount_nfs.8
index 93ea3c2..a8d410f 100644
--- a/sbin/mount_nfs/mount_nfs.8
+++ b/sbin/mount_nfs/mount_nfs.8
@@ -142,11 +142,11 @@ The default is a retry count of zero, which means to keep retrying
 forever.
 There is a 60 second delay between each attempt.
 .It Fl T
-Use TCP transport instead of UDP.
-This is recommended for servers that are not on the same LAN cable as
-the client.
-Not all NFS servers support this method, especially older ones;
-caution should be observed in these cases.
+Use TCP transport.
+This is the default option, as it provides for increased reliability on both
+LAN and WAN configurations compared to UDP.
+Some old NFS servers do not support this method; UDP mounts may be required
+for interoperability.
 .It Fl U
 Force the mount protocol to use UDP transport, even for TCP NFS mounts.
 (Necessary for some old
diff --git a/sbin/mount_nfs/mount_nfs.c b/sbin/mount_nfs/mount_nfs.c
index 44d45e8..48c0a1f 100644
--- a/sbin/mount_nfs/mount_nfs.c
+++ b/sbin/mount_nfs/mount_nfs.c
@@ -155,7 +155,7 @@ struct nfs_args nfsdefargs = {
 	NFS_ARGSVERSION,
 	NULL,
 	sizeof (struct sockaddr_in),
-	SOCK_DGRAM,
+	SOCK_STREAM,
 	0,
 	NULL,
 	0,