VPN documentation proofreading (#1506)

* Fix typos in openconnect.rst

change Cerbort->Certbot
Update first line to reflect that openconnect was introduced in 1.3-rolling (T2036)

* typo in dmvpn.rst

* ipsec.rst justification, minor phrasing changes

* l2tp.rst justification and phrasing changes.

* sstp.rst phrasing, justification changes

* Update ipsec.rst

rephrase for clarity and to avoid possessive plural apostrophe

1 files changed, 59 insertions, 54 deletions

diff --git a/docs/configuration/vpn/sstp.rst b/docs/configuration/vpn/sstp.rst
index cd064162..e750cdcf 100644
--- a/docs/configuration/vpn/sstp.rst
+++ b/docs/configuration/vpn/sstp.rst
@@ -16,8 +16,8 @@ SSTP is available for Linux, BSD, and Windows.
 VyOS utilizes accel-ppp_ to provide SSTP server functionality. We support both
 local and RADIUS authentication.
 
-As SSTP provides PPP via a SSL/TLS channel the use of either publically signed
-certificates as well as a private PKI is required.
+As SSTP provides PPP via a SSL/TLS channel the use of either publicly signed
+certificates or private PKI is required.
 
 ***********************
 Configuring SSTP Server
@@ -92,8 +92,8 @@ Configuring RADIUS authentication
 *********************************
 
 To enable RADIUS based authentication, the authentication mode needs to be
-changed within the configuration. Previous settings like the local users, still
-exists within the configuration, however they are not used if the mode has been
+changed within the configuration. Previous settings like the local users still
+exist within the configuration, however they are not used if the mode has been
 changed from local to radius. Once changed back to local, it will use all local
 accounts again.
 
@@ -121,15 +121,15 @@ For example:
 RADIUS source address
 =====================
 
-If you are using OSPF as IGP, always the closest interface connected to the
-RADIUS server is used. You can bind all outgoing RADIUS requests
-to a single source IP e.g. the loopback interface.
+If you are using OSPF as your IGP, use the interface connected closest to the
+RADIUS server. You can bind all outgoing RADIUS requests to a single source IP
+e.g. the loopback interface.
 
 .. cfgcmd:: set vpn sstp authentication radius source-address <address>
 
   Source IPv4 address used in all RADIUS server queires.
 
-.. note:: The ``source-address`` must be configured on one of VyOS interface.
+.. note:: The ``source-address`` must be configured to that of an interface.
    Best practice would be a loopback or dummy interface.
 
 RADIUS advanced options
@@ -191,7 +191,7 @@ RADIUS advanced options
   The default attribute is `Filter-Id`.
 
 .. note:: If you set a custom RADIUS attribute you must define it on both
-   dictionaries at RADIUS server and client.
+   dictionaries on the RADIUS server and client.
 
 .. cfgcmd:: set vpn sstp authentication radius rate-limit enable
 
@@ -199,7 +199,7 @@ RADIUS advanced options
 
 .. cfgcmd:: set vpn sstp authentication radius rate-limit vendor
 
-  Specifies the vendor dictionary, dictionary needs to be in
+  Specifies the vendor dictionary, This dictionary needs to be present in
   /usr/share/accel-ppp/radius.
 
 Received RADIUS attributes have a higher priority than parameters defined within
@@ -209,25 +209,28 @@ Allocation clients ip addresses by RADIUS
 =========================================
 
 If the RADIUS server sends the attribute ``Framed-IP-Address`` then this IP
-address will be allocated to the client and the option ``default-pool`` within the CLI
-config is being ignored.
+address will be allocated to the client and the option ``default-pool`` within
+the CLI config will being ignored.
 
-If the RADIUS server sends the attribute ``Framed-Pool``, IP address will be allocated
-from a predefined IP pool whose name equals the attribute value.
+If the RADIUS server sends the attribute ``Framed-Pool``, then the IP address
+will be allocated from a predefined IP pool whose name equals the attribute
+value.
 
-If the RADIUS server sends the attribute ``Stateful-IPv6-Address-Pool``, IPv6 address
-will be allocated from a predefined IPv6 pool ``prefix`` whose name equals the attribute value.
+If the RADIUS server sends the attribute ``Stateful-IPv6-Address-Pool``, the
+IPv6 address will be allocated from a predefined IPv6 pool ``prefix`` whose
+name equals the attribute value.
 
-If the RADIUS server sends the attribute ``Delegated-IPv6-Prefix-Pool``, IPv6
-delegation pefix will be allocated from a predefined IPv6 pool ``delegate``
+If the RADIUS server sends the attribute ``Delegated-IPv6-Prefix-Pool``, an
+IPv6 delegation prefix will be allocated from a predefined IPv6 pool ``delegate``
 whose name equals the attribute value.
 
 .. note:: ``Stateful-IPv6-Address-Pool`` and ``Delegated-IPv6-Prefix-Pool`` are defined in
           RFC6911. If they are not defined in your RADIUS server, add new dictionary_.
 
-User interface can be put to VRF context via RADIUS Access-Accept packet, or change
-it via RADIUS CoA. ``Accel-VRF-Name`` is used from these purposes. It is custom `ACCEL-PPP attribute`_.
-Define it in your RADIUS server.
+The client's interface can be put into a VRF context via a RADIUS Access-Accept
+packet, or changed via RADIUS CoA. ``Accel-VRF-Name`` is used for these
+purposes. This is a custom `ACCEL-PPP attribute`_. Define it in your RADIUS
+server.
 
 Renaming clients interfaces by RADIUS
 =====================================
@@ -254,19 +257,19 @@ IPv6
 .. cfgcmd:: set vpn sstp client-ipv6-pool <IPv6-POOL-NAME> prefix <address>
    mask <number-of-bits>
 
-  Use this comand to set the IPv6 address pool from which an SSTP client
-  will get an IPv6 prefix of your defined length (mask) to terminate the
-  SSTP endpoint at their side. The mask length can be set from 48 to 128
-  bit long, the default value is 64.
+  Use this comand to set the IPv6 address pool from which an SSTP client will
+  get an IPv6 prefix of your defined length (mask) to terminate the SSTP
+  endpoint at their side. The mask length can be set between 48 and 128 bits
+  long, the default value is 64.
 
 .. cfgcmd:: set vpn sstp client-ipv6-pool <IPv6-POOL-NAME> delegate <address>
    delegation-prefix <number-of-bits>
 
-  Use this command to configure DHCPv6 Prefix Delegation (RFC3633) on
-  SSTP. You will have to set your IPv6 pool and the length of the
-  delegation prefix. From the defined IPv6 pool you will be handing out
-  networks of the defined length (delegation-prefix). The length of the
-  delegation prefix can be set from 32 to 64 bit long.
+  Use this command to configure DHCPv6 Prefix Delegation (RFC3633) on SSTP. You
+  will have to set your IPv6 pool and the length of the delegation prefix. From
+  the defined IPv6 pool you will be handing out networks of the defined length
+  (delegation-prefix). The length of the delegation prefix can be set between 
+  32 and 64 bits long.
 
 .. cfgcmd:: set vpn sstp default-ipv6-pool <IPv6-POOL-NAME>
 
@@ -283,19 +286,19 @@ IPv6 Advanced Options
 =====================
 .. cfgcmd:: set vpn sstp ppp-options ipv6-accept-peer-interface-id
 
-  Accept peer interface identifier. By default is not defined.
+  Accept peer interface identifier. By default this is not defined.
 
 .. cfgcmd:: set vpn sstp ppp-options ipv6-interface-id <random | x:x:x:x>
 
-  Specifies fixed or random interface identifier for IPv6.
-  By default is fixed.
+  Specifies if a fixed or random interface identifier is used for IPv6. The
+  default is fixed.
 
   * **random** - Random interface identifier for IPv6
   * **x:x:x:x** - Specify interface identifier for IPv6
 
 .. cfgcmd:: set vpn sstp ppp-options ipv6-interface-id <random | x:x:x:x>
 
-  Specifies peer interface identifier for IPv6. By default is fixed.
+  Specifies the peer interface identifier for IPv6. The default is fixed.
 
   * **random** - Random interface identifier for IPv6
   * **x:x:x:x** - Specify interface identifier for IPv6
@@ -308,19 +311,19 @@ Scripting
 
 .. cfgcmd:: set vpn sstp extended-scripts on-change <path_to_script>
 
-  Script to run when session interface changed by RADIUS CoA handling
+  Script to run when the session interface is changed by RADIUS CoA handling
 
 .. cfgcmd:: set vpn sstp extended-scripts on-down <path_to_script>
 
-  Script to run when session interface going to terminate
+  Script to run when the session interface about to terminate
 
 .. cfgcmd:: set vpn sstp extended-scripts on-pre-up <path_to_script>
 
-  Script to run before session interface comes up
+  Script to run before the session interface comes up
 
 .. cfgcmd:: set vpn sstp extended-scripts on-up <path_to_script>
 
-  Script to run when session interface is completely configured and started
+  Script to run when the session interface is completely configured and started
 
 ****************
 Advanced Options
@@ -336,17 +339,17 @@ Authentication Advanced Options
 .. cfgcmd:: set vpn sstp authentication local-users username <user> static-ip
    <address>
 
-  Assign static IP address to `<user>` account.
+  Assign a static IP address to `<user>` account.
 
 .. cfgcmd:: set vpn sstp authentication local-users username <user> rate-limit
    download <bandwidth>
 
-  Download bandwidth limit in kbit/s for `<user>`.
+  Rate limit the download bandwidth for `<user>` to `<bandwidth>` kbit/s.
 
 .. cfgcmd:: set vpn sstp authentication local-users username <user> rate-limit
    upload <bandwidth>
 
-  Upload bandwidth limit in kbit/s for `<user>`.
+  Rate limit the upload bandwidth for `<user>` to `<bandwidth>` kbit/s.
 
 .. cfgcmd:: set vpn sstp authentication protocols
    <pap | chap | mschap | mschap-v2>
@@ -371,10 +374,10 @@ PPP Advanced Options
 
 .. cfgcmd:: set vpn sstp ppp-options interface-cache <number>
 
-  Specifies number of interfaces to keep in cache. It means that don’t
-  destroy interface after corresponding session is destroyed, instead
-  place it to cache and use it later for new sessions repeatedly.
-  This should reduce kernel-level interface creation/deletion rate lack.
+  Specifies number of interfaces to cache. This prevents interfaces from being
+  removed once the corresponding session is destroyed. Instead, interfaces are
+  cached for later use in new sessions. This should reduce the kernel-level
+  interface creation/deletion rate.
   Default value is **0**.
 
 .. cfgcmd:: set vpn sstp ppp-options ipv4 <require | prefer | allow | deny>
@@ -394,19 +397,20 @@ PPP Advanced Options
 .. cfgcmd:: set vpn sstp ppp-options lcp-echo-interval <interval>
 
   If this option is specified and is greater than 0, then the PPP module will
-  send LCP pings of the echo request every `<interval>` seconds.
+  send LCP echo requests every `<interval>` seconds.
   Default value is **30**.
 
 .. cfgcmd:: set vpn sstp ppp-options lcp-echo-timeout
 
-  Specifies timeout in seconds to wait for any peer activity. If this option
+  Specifies timeout in seconds to wait for any peer activity. If this option is
   specified it turns on adaptive lcp echo functionality and "lcp-echo-failure"
   is not used. Default value is **0**.
 
 .. cfgcmd:: set vpn sstp ppp-options min-mtu <number>
 
-  Defines minimum acceptable MTU. If client will try to negotiate less then
-  specified MTU then it will be NAKed or disconnected if rejects greater MTU.
+  Defines the minimum acceptable MTU. If a client tries to negotiate an MTU
+  lower than this it will be NAKed, and disconnected if it rejects a greater
+  MTU.
   Default value is **100**.
 
 .. cfgcmd:: set vpn sstp ppp-options mppe <require | prefer | deny>
@@ -418,7 +422,8 @@ PPP Advanced Options
   * **prefer** - ask client for mppe, if it rejects don't fail. (Default value)
   * **deny** - deny mppe
 
-  Default behavior - don't ask client for mppe, but allow it if client wants.
+  Default behavior - don't ask the client for mppe, but allow it if the client
+  wants.
   Please note that RADIUS may override this option by MS-MPPE-Encryption-Policy
   attribute.
 
@@ -439,7 +444,7 @@ Global Advanced options
 
 .. cfgcmd:: set vpn sstp limits connection-limit <value>
 
-  Acceptable rate of connections (e.g. 1/min, 60/sec)
+  Maximum accepted connection rate (e.g. 1/min, 60/sec)
 
 .. cfgcmd:: set vpn sstp limits timeout <value>
 
@@ -455,9 +460,9 @@ Global Advanced options
 
 .. cfgcmd:: set vpn sstp name-server <address>
 
-  Connected client should use `<address>` as their DNS server. This
-  command accepts both IPv4 and IPv6 addresses. Up to two nameservers
-  can be configured for IPv4, up to three for IPv6.
+  Connected clients should use `<address>` as their DNS server. This command
+  accepts both IPv4 and IPv6 addresses. Up to two nameservers can be configured
+  for IPv4, up to three for IPv6.
 
 .. cfgcmd:: set vpn sstp shaper fwmark <1-2147483647>