ftp.microsoft.com is dead and the document was not archived, point to the full

protocol spec document instead.
Fix spelling mistake flagged by igor.
Rephrase bad sentence flagged by igor.

Approved by:	bcr (mentor)
MFC after:	5 days
Differential Revision:	 https://reviews.freebsd.org/D10111

usr.sbin/ppp/ppp.8

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 25, 2009
+.Dd March 25, 2017
 .Dt PPP 8
 .Os
 .Sh NAME
@@ -265,7 +265,7 @@ will force it to exit.
 .It Supports client callback.
 .Nm
 can use either the standard LCP callback protocol or the Microsoft
-CallBack Control Protocol (ftp://ftp.microsoft.com/developr/rfc/cbcp.txt).
+CallBack Control Protocol (https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-CBCP/[MS-CBCP].pdf).
 .It Supports NAT or packet aliasing.
 Packet aliasing (a.k.a.\& IP masquerading) allows computers on a
 private, unregistered network to access the Internet.
@@ -3523,7 +3523,7 @@ for details of the available commands.
 This command tells
 .Nm
 to punch holes in the firewall for FTP or IRC DCC connections.
-This is done dynamically by installing termporary firewall rules which
+This is done dynamically by installing temporary firewall rules which
 allow a particular connection (and only that connection) to go through
 the firewall.
 The rules are removed once the corresponding connection terminates.
@@ -5555,7 +5555,7 @@ seconds.
 .It set rad_port_id Ar option
 When RADIUS is configured, setting the
 .Dq rad_port_id
-value allows to specify what should be sent to the RADIUS server as
+value specifies what should be sent to the RADIUS server as
 NAS-Port-Id.
 The
 .Ar option Ns No s