When counting queue, avoid building & sorting list of names

[users/jgh/exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 1d6fa536b45352f7fdb1fe31acc71a2d5a45b3f4..bba71b76d14d04f55bbf6adea73386208c3c46de 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -3966,7 +3966,7 @@ user.
 .vitem &%-MG%&&~<&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~...
 .oindex "&%-MG%&"
 .cindex queue named
 .vitem &%-MG%&&~<&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~...
 .oindex "&%-MG%&"
 .cindex queue named

-.cindex "named queues"
+.cindex "named queues" "moving messages"

 .cindex "queue" "moving messages"
 This option requests that each listed message be moved from its current
 queue to the given named queue.
 .cindex "queue" "moving messages"
 This option requests that each listed message be moved from its current
 queue to the given named queue.


@@ -4185,6 +4185,7 @@ forces queueing.
 .vitem &%-odqs%&
 .oindex "&%-odqs%&"
 .cindex "SMTP" "delaying delivery"
 .vitem &%-odqs%&
 .oindex "&%-odqs%&"
 .cindex "SMTP" "delaying delivery"

+.cindex "first pass routing"

 This option is a hybrid between &%-odb%&/&%-odi%& and &%-odq%&.
 However, like &%-odb%& and &%-odi%&, this option has no effect if
 &%queue_only_override%& is false and one of the queueing options in the
 This option is a hybrid between &%-odb%&/&%-odi%& and &%-odq%&.
 However, like &%-odb%& and &%-odi%&, this option has no effect if
 &%queue_only_override%& is false and one of the queueing options in the


@@ -4503,11 +4504,16 @@ appear in the correct order. Each flag is described in a separate item below.
 .cindex "queue" "double scanning"
 .cindex "queue" "routing"
 .cindex "routing" "whole queue before delivery"
 .cindex "queue" "double scanning"
 .cindex "queue" "routing"
 .cindex "routing" "whole queue before delivery"

+.cindex "first pass routing"

 An option starting with &%-qq%& requests a two-stage queue run. In the first
 stage, the queue is scanned as if the &%queue_smtp_domains%& option matched
 every domain. Addresses are routed, local deliveries happen, but no remote
 transports are run.
 
 An option starting with &%-qq%& requests a two-stage queue run. In the first
 stage, the queue is scanned as if the &%queue_smtp_domains%& option matched
 every domain. Addresses are routed, local deliveries happen, but no remote
 transports are run.
 

+.new
+Performance will be best if the &%queue_run_in_order%& option is false.
+.wen
+

 .cindex "hints database" "remembering routing"
 The hints database that remembers which messages are waiting for specific hosts
 is updated, as if delivery to those hosts had been deferred. After this is
 .cindex "hints database" "remembering routing"
 The hints database that remembers which messages are waiting for specific hosts
 is updated, as if delivery to those hosts had been deferred. After this is


@@ -4553,7 +4559,7 @@ for later delivery.
 .vitem &%-q[q][i][f[f]][l][G<name>[/<time>]]]%&
 .oindex "&%-qG%&"
 .cindex queue named
 .vitem &%-q[q][i][f[f]][l][G<name>[/<time>]]]%&
 .oindex "&%-qG%&"
 .cindex queue named

-.cindex "named queues"
+.cindex "named queues" "deliver from"

 .cindex "queue" "delivering specific messages"
 If the &'G'& flag and a name is present, the queue runner operates on the
 queue with the given name rather than the default queue.
 .cindex "queue" "delivering specific messages"
 If the &'G'& flag and a name is present, the queue runner operates on the
 queue with the given name rather than the default queue.


@@ -8300,6 +8306,19 @@ domainlist  dom2 = !a.b : *.b
 where &'x.y'& does not match. It's best to avoid negation altogether in
 referenced lists if you can.
 
 where &'x.y'& does not match. It's best to avoid negation altogether in
 referenced lists if you can.
 

+.new
+.cindex "hiding named list values"
+.cindex "named lists" "hiding value of"
+Some named list definitions may contain sensitive data, for example, passwords for
+accessing databases. To stop non-admin users from using the &%-bP%& command
+line option to read these values, you can precede the definition with the
+word &"hide"&. For example:
+.code
+hide domainlist filter_for_domains = ldap;PASS=secret ldap::/// ...
+.endd
+.wen
+
+

 Named lists may have a performance advantage. When Exim is routing an
 address or checking an incoming message, it caches the result of tests on named
 lists. So, if you have a setting such as
 Named lists may have a performance advantage. When Exim is routing an
 address or checking an incoming message, it caches the result of tests on named
 lists. So, if you have a setting such as


@@ -9719,7 +9738,7 @@ letters appear. For example:
        "&*$bheader_*&<&'header&~name'&>&*:*&&~or&~&&&
         &*$bh_*&<&'header&~name'&>&*:*&" &&&
        "&*$lheader_*&<&'header&~name'&>&*:*&&~or&~&&&
        "&*$bheader_*&<&'header&~name'&>&*:*&&~or&~&&&
         &*$bh_*&<&'header&~name'&>&*:*&" &&&
        "&*$lheader_*&<&'header&~name'&>&*:*&&~or&~&&&

-        &*$lh_*&<&'header&~name'&>&*:*&"
+        &*$lh_*&<&'header&~name'&>&*:*&" &&&

        "&*$rheader_*&<&'header&~name'&>&*:*&&~or&~&&&
         &*$rh_*&<&'header&~name'&>&*:*&"
 .cindex "expansion" "header insertion"
        "&*$rheader_*&<&'header&~name'&>&*:*&&~or&~&&&
         &*$rh_*&<&'header&~name'&>&*:*&"
 .cindex "expansion" "header insertion"


@@ -12831,10 +12850,17 @@ or if not set, the value of &$qualify_domain$&.
 
 .vitem &$queue_name$&
 .vindex &$queue_name$&
 
 .vitem &$queue_name$&
 .vindex &$queue_name$&

-.cindex "named queues"
+.cindex "named queues" variable

 .cindex queues named
 The name of the spool queue in use; empty for the default queue.
 
 .cindex queues named
 The name of the spool queue in use; empty for the default queue.
 

+.vitem &$queue_size$&
+.vindex "&$queue_size$&"
+.cindex "queue" "size of"
+.cindex "spool" "number of messages"
+This variable contains the number of messages queued.
+It is evaluated on demand, but no more often than once every minute.
+

 .vitem &$r_...$&
 .vindex &$r_...$&
 .cindex router variables
 .vitem &$r_...$&
 .vindex &$r_...$&
 .cindex router variables


@@ -16746,13 +16772,14 @@ run. If you do not want queue runs to occur, omit the &%-q%&&'xx'& setting on
 the daemon's command line.
 
 .cindex queues named
 the daemon's command line.
 
 .cindex queues named

-.cindex "named queues"
+.cindex "named queues" "resource limit"

 To set limits for different named queues use
 an expansion depending on the &$queue_name$& variable.
 
 .option queue_smtp_domains main "domain list&!!" unset
 .cindex "queueing incoming messages"
 .cindex "message" "queueing remote deliveries"
 To set limits for different named queues use
 an expansion depending on the &$queue_name$& variable.
 
 .option queue_smtp_domains main "domain list&!!" unset
 .cindex "queueing incoming messages"
 .cindex "message" "queueing remote deliveries"

+.cindex "first pass routing"

 When this option is set, a delivery process is started whenever a message is
 received, routing is performed, and local deliveries take place.
 However, if any SMTP deliveries are required for domains that match
 When this option is set, a delivery process is started whenever a message is
 received, routing is performed, and local deliveries take place.
 However, if any SMTP deliveries are required for domains that match


@@ -17254,6 +17281,13 @@ example:
 smtp_etrn_command = /etc/etrn_command $domain \
                     $sender_host_address
 .endd
 smtp_etrn_command = /etc/etrn_command $domain \
                     $sender_host_address
 .endd

+.new
+If the option is not set, the argument for the ETRN command must
+be a &'#'& followed by an address string.
+In this case an &'exim -R <string>'& command is used;
+if the ETRN ACL has set up a named-queue then &'-MCG <queue>'& is appended.
+.wen
+

 A new process is created to run the command, but Exim does not wait for it to
 complete. Consequently, its status cannot be checked. If the command cannot be
 run, a line is written to the panic log, but the ETRN caller still receives
 A new process is created to run the command, but Exim does not wait for it to
 complete. Consequently, its status cannot be checked. If the command cannot be
 run, a line is written to the panic log, but the ETRN caller still receives


@@ -18634,15 +18668,19 @@ avoided. The &%repeat_use%& option of the &%redirect%& router may be of help.
 This option specifies a list of text headers,
 colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&),
 that is associated with any addresses that are accepted by the router.
 This option specifies a list of text headers,
 colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&),
 that is associated with any addresses that are accepted by the router.

-Each item is separately expanded, at routing time.  However, this
-option has no effect when an address is just being verified. The way in which
+However, the option has no effect when an address is just being verified.
+Each list item is separately expanded, at transport time.
+.new
+If an item ends in *, it will match any header with the given prefix.
+.wen
+The way in which

 the text is used to remove header lines at transport time is described in
 section &<<SECTheadersaddrem>>&. Header lines are not actually removed until
 the message is in the process of being transported. This means that references
 to header lines in string expansions in the transport's configuration still
 &"see"& the original header lines.
 
 the text is used to remove header lines at transport time is described in
 section &<<SECTheadersaddrem>>&. Header lines are not actually removed until
 the message is in the process of being transported. This means that references
 to header lines in string expansions in the transport's configuration still
 &"see"& the original header lines.
 

-The &%headers_remove%& option is expanded after &%errors_to%& and
+The &%headers_remove%& option is handled after &%errors_to%& and

 &%headers_add%&, but before &%transport%&. If an item expansion is forced to fail,
 the item has no effect. Other expansion failures are treated as configuration
 errors.
 &%headers_add%&, but before &%transport%&. If an item expansion is forced to fail,
 the item has no effect. Other expansion failures are treated as configuration
 errors.


@@ -21821,15 +21859,21 @@ checked, since this option does not automatically suppress them.
 .option headers_remove transports list&!! unset
 .cindex "header lines" "removing"
 .cindex "transport" "header lines; removing"
 .option headers_remove transports list&!! unset
 .cindex "header lines" "removing"
 .cindex "transport" "header lines; removing"

-This option specifies a list of header names,
-colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&);
-these headers are omitted from the message as it is transported, as described
-in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
-routers.
+This option specifies a list of text headers,
+colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&),
+to be removed from the message.
+However, the option has no effect when an address is just being verified.

 Each list item is separately expanded.
 If the result of the expansion is an empty string, or if the expansion
 is forced to fail, no action is taken. Other expansion failures are treated as
 errors and cause the delivery to be deferred.
 Each list item is separately expanded.
 If the result of the expansion is an empty string, or if the expansion
 is forced to fail, no action is taken. Other expansion failures are treated as
 errors and cause the delivery to be deferred.

+.new
+If an item ends in *, it will match any header with the given prefix.
+.wen
+
+Matching headers are omitted from the message as it is transported, as described
+in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
+routers.

 
 Unlike most options, &%headers_remove%& can be specified multiple times
 for a transport; all listed headers are removed.
 
 Unlike most options, &%headers_remove%& can be specified multiple times
 for a transport; all listed headers are removed.


@@ -27024,7 +27068,7 @@ There are good and bad examples at the end of the next section.
 
 .section "The PLAIN authentication mechanism" "SECID172"
 .cindex "PLAIN authentication mechanism"
 
 .section "The PLAIN authentication mechanism" "SECID172"
 .cindex "PLAIN authentication mechanism"

-.cindex "authentication" "PLAIN mechanism"
+.cindex authentication PLAIN

 .cindex "binary zero" "in &(plaintext)& authenticator"
 The PLAIN authentication mechanism (RFC 2595) specifies that three strings be
 sent as one item of data (that is, one combined string containing two NUL
 .cindex "binary zero" "in &(plaintext)& authenticator"
 The PLAIN authentication mechanism (RFC 2595) specifies that three strings be
 sent as one item of data (that is, one combined string containing two NUL


@@ -27106,7 +27150,7 @@ writing the test makes the logic clearer.
 
 .section "The LOGIN authentication mechanism" "SECID173"
 .cindex "LOGIN authentication mechanism"
 
 .section "The LOGIN authentication mechanism" "SECID173"
 .cindex "LOGIN authentication mechanism"

-.cindex "authentication" "LOGIN mechanism"
+.cindex authentication LOGIN

 The LOGIN authentication mechanism is not documented in any RFC, but is in use
 in a number of programs. No data is sent with the AUTH command. Instead, a
 user name and password are supplied separately, in response to prompts. The
 The LOGIN authentication mechanism is not documented in any RFC, but is in use
 in a number of programs. No data is sent with the AUTH command. Instead, a
 user name and password are supplied separately, in response to prompts. The


@@ -27227,7 +27271,7 @@ prompts.
 .scindex IIDcramauth1 "&(cram_md5)& authenticator"
 .scindex IIDcramauth2 "authenticators" "&(cram_md5)&"
 .cindex "CRAM-MD5 authentication mechanism"
 .scindex IIDcramauth1 "&(cram_md5)& authenticator"
 .scindex IIDcramauth2 "authenticators" "&(cram_md5)&"
 .cindex "CRAM-MD5 authentication mechanism"

-.cindex "authentication" "CRAM-MD5 mechanism"
+.cindex authentication CRAM-MD5

 The CRAM-MD5 authentication mechanism is described in RFC 2195. The server
 sends a challenge string to the client, and the response consists of a user
 name and the CRAM-MD5 digest of the challenge string combined with a secret
 The CRAM-MD5 authentication mechanism is described in RFC 2195. The server
 sends a challenge string to the client, and the response consists of a user
 name and the CRAM-MD5 digest of the challenge string combined with a secret


@@ -27516,10 +27560,7 @@ auth_mechanisms = plain login ntlm
 .cindex "authentication" "LOGIN"
 .cindex "authentication" "DIGEST-MD5"
 .cindex "authentication" "CRAM-MD5"
 .cindex "authentication" "LOGIN"
 .cindex "authentication" "DIGEST-MD5"
 .cindex "authentication" "CRAM-MD5"

-.cindex "authentication" "SCRAM-SHA-1"
-.cindex "authentication" "SCRAM-SHA-1-PLUS"
-.cindex "authentication" "SCRAM-SHA-256"
-.cindex "authentication" "SCRAM-SHA-256-PLUS"
+.cindex "authentication" "SCRAM family"

 The &(gsasl)& authenticator provides integration for the GNU SASL
 library and the mechanisms it provides.  This is new as of the 4.80 release
 and there are a few areas where the library does not let Exim smoothly
 The &(gsasl)& authenticator provides integration for the GNU SASL
 library and the mechanisms it provides.  This is new as of the 4.80 release
 and there are a few areas where the library does not let Exim smoothly


@@ -27553,6 +27594,19 @@ This option is exapanded before use, and should result in
 the account name to be used.
 .wen
 
 the account name to be used.
 .wen
 

+.new
+.option client_spassword gsasl string&!! unset
+If a SCRAM mechanism is being used and this option is set
+it is used in preference to &%client_password%&.
+The value after expansion should be
+a 40 (for SHA-1) or 64 (for SHA-256) character string
+with the PBKDF2-prepared password, hex-encoded.
+Note that this value will depend on the salt and iteration-count
+supplied by the server.
+.wen
+
+
+

 .option server_channelbinding gsasl boolean false
 Do not set this true and rely on the properties
 without consulting a cryptographic engineer.
 .option server_channelbinding gsasl boolean false
 Do not set this true and rely on the properties
 without consulting a cryptographic engineer.


@@ -27629,7 +27683,8 @@ Some mechanisms will use this data.
 .option server_scram_iter gsasl string&!! 4096
 This option provides data for the SCRAM family of mechanisms.
 .new
 .option server_scram_iter gsasl string&!! 4096
 This option provides data for the SCRAM family of mechanisms.
 .new

-The &$auth1$&, &$auth2$& and &$auth3$& variables are available for expansion.
+The &$auth1$&, &$auth2$& and &$auth3$& variables are available
+when this option is expanded.

 
 The result of expansion should be a decimal number,
 and represents both a lower-bound on the security, and
 
 The result of expansion should be a decimal number,
 and represents both a lower-bound on the security, and


@@ -27637,19 +27692,50 @@ a compute cost factor imposed on the client
 (if it does not cache results, or the server changes
 either the iteration count or the salt).
 A minimum value of 4096 is required by the standards
 (if it does not cache results, or the server changes
 either the iteration count or the salt).
 A minimum value of 4096 is required by the standards

-for all current CRAM mechanism variants.
+for all current SCRAM mechanism variants.

 .wen
 
 .wen
 

-

 .option server_scram_salt gsasl string&!! unset
 This option provides data for the SCRAM family of mechanisms.
 .new
 .option server_scram_salt gsasl string&!! unset
 This option provides data for the SCRAM family of mechanisms.
 .new

-The &$auth1$&, &$auth2$& and &$auth3$& variables are available for expansion.
+The &$auth1$&, &$auth2$& and &$auth3$& variables are available
+when this option is expanded.
+The value should be a base64-encoded string,
+of random data typically 4-to-16 bytes long.

 If unset or empty after expansion the library will provides a value for the
 protocol conversation.
 .wen
 
 
 If unset or empty after expansion the library will provides a value for the
 protocol conversation.
 .wen
 
 

+.new
+.option server_key gsasl string&!! unset
+.option server_skey gsasl string&!! unset
+These options can be used for the SCRAM family of mechanisms
+to provide stored information related to a password,
+the storage of which is preferable to plaintext.
+
+&%server_key%& is the value defined in the SCRAM standards as ServerKey;
+&%server_skey%& is StoredKey.
+
+They are only available for version 1.9.0 (or later) of the gsasl library.
+When this is so, the macros
+_OPT_AUTHENTICATOR_GSASL_SERVER_KEY
+and _HAVE_AUTH_GSASL_SCRAM_S_KEY
+will be defined.
+
+The &$authN$& variables are available when these options are expanded.
+
+If set, the results of expansion should for each
+should be a 28 (for SHA-1) or 44 (for SHA-256) character string
+of base64-coded data, and will be used in preference to the
+&%server_password%& option.
+If unset or not of the right length, &%server_password%& will be used.
+
+The libgsasl library release includes a utility &'gsasl'& which can be used
+to generate these values.
+.wen
+
+

 .option server_service gsasl string &`smtp`&
 This is the SASL service that the server claims to implement.
 Some mechanisms will use this data.
 .option server_service gsasl string &`smtp`&
 This is the SASL service that the server claims to implement.
 Some mechanisms will use this data.


@@ -30079,7 +30165,7 @@ in several different ways. For example:
 It can be at the end of an &%accept%& statement:
 .code
     accept  ...some conditions
 It can be at the end of an &%accept%& statement:
 .code
     accept  ...some conditions

-            control = queue_only
+            control = queue

 .endd
 In this case, the control is applied when this statement yields &"accept"&, in
 other words, when the conditions are all true.
 .endd
 In this case, the control is applied when this statement yields &"accept"&, in
 other words, when the conditions are all true.


@@ -30088,7 +30174,7 @@ other words, when the conditions are all true.
 It can be in the middle of an &%accept%& statement:
 .code
     accept  ...some conditions...
 It can be in the middle of an &%accept%& statement:
 .code
     accept  ...some conditions...

-            control = queue_only
+            control = queue

             ...some more conditions...
 .endd
 If the first set of conditions are true, the control is applied, even if the
             ...some more conditions...
 .endd
 If the first set of conditions are true, the control is applied, even if the


@@ -30659,16 +30745,32 @@ response to an EHLO command. Therefore, it should normally appear in an ACL
 controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also
 &%pipelining_advertise_hosts%&.
 
 controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also
 &%pipelining_advertise_hosts%&.
 

-.vitem &*control&~=&~queue_only*&
+.new
+.vitem &*control&~=&~queue/*&<&'options'&>* &&&
+       &*control&~=&~queue_only*&
+.oindex "&%queue%&"

 .oindex "&%queue_only%&"
 .cindex "queueing incoming messages"
 .oindex "&%queue_only%&"
 .cindex "queueing incoming messages"

+.cindex queueing "forcing in ACL"
+.cindex "first pass routing"

 This control is permitted only for the MAIL, RCPT, DATA, and non-SMTP ACLs, in
 other words, only when a message is being received. If the message is accepted,
 it is placed on Exim's queue and left there for delivery by a subsequent queue
 This control is permitted only for the MAIL, RCPT, DATA, and non-SMTP ACLs, in
 other words, only when a message is being received. If the message is accepted,
 it is placed on Exim's queue and left there for delivery by a subsequent queue

-runner. No immediate delivery process is started. In other words, it has the
-effect as the &%queue_only%& global option. However, the control applies only
-to the current message, not to any subsequent ones that may be received in the
-same SMTP connection.
+runner.
+If used with no options set,
+no immediate delivery process is started. In other words, it has the
+effect as the &%queue_only%& global option or &'-odq'& command-line option.
+
+If the &'first_pass_route'& option is given then
+the behaviour is like the command-line &'-oqds'& option;
+a delivery process is started which stops short of making
+any SMTP delivery.  The benefit is that the hints database will be updated for
+the message being waiting for a specific host, and a later queue run will be
+able to send all such messages on a single connection.
+
+The control only applies to the current message, not to any subsequent ones that
+ may be received in the same SMTP connection.
+.wen

 
 .vitem &*control&~=&~submission/*&<&'options'&>
 .cindex "message" "submission"
 
 .vitem &*control&~=&~submission/*&<&'options'&>
 .cindex "message" "submission"


@@ -33819,13 +33921,14 @@ in &_Local/Makefile_& (see section &<<SECTconoptloc>>& below).
 .cindex &%dlfunc%& "API description"
 You must include this line near the start of your code:
 .code
 .cindex &%dlfunc%& "API description"
 You must include this line near the start of your code:
 .code

+#define LOCAL_SCAN

 #include "local_scan.h"
 .endd
 This header file defines a number of variables and other values, and the
 prototype for the function itself. Exim is coded to use unsigned char values
 almost exclusively, and one of the things this header defines is a shorthand
 for &`unsigned char`& called &`uschar`&.
 #include "local_scan.h"
 .endd
 This header file defines a number of variables and other values, and the
 prototype for the function itself. Exim is coded to use unsigned char values
 almost exclusively, and one of the things this header defines is a shorthand
 for &`unsigned char`& called &`uschar`&.

-It also contains the following macro definitions, to simplify casting character
+It also makes available the following macro definitions, to simplify casting character

 strings and pointers to character strings:
 .code
 #define CS   (char *)
 strings and pointers to character strings:
 .code
 #define CS   (char *)


@@ -36801,6 +36904,7 @@ delivered immediately.
 .cindex "SMTP" "passed connection"
 .cindex "SMTP" "multiple deliveries"
 .cindex "multiple SMTP deliveries"
 .cindex "SMTP" "passed connection"
 .cindex "SMTP" "multiple deliveries"
 .cindex "multiple SMTP deliveries"

+.cindex "first pass routing"

 Mail waiting to be sent from an intermittently connected host will probably
 not have been routed, because without a connection DNS lookups are not
 possible. This means that if a normal queue run is done at connection time,
 Mail waiting to be sent from an intermittently connected host will probably
 not have been routed, because without a connection DNS lookups are not
 possible. This means that if a normal queue run is done at connection time,


@@ -40078,6 +40182,8 @@ To generate keys under OpenSSL:
 openssl genrsa -out dkim_rsa.private 2048
 openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
 .endd
 openssl genrsa -out dkim_rsa.private 2048
 openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
 .endd

+The result file from the first command should be retained, and
+this option set to use it.

 Take the base-64 lines from the output of the second command, concatenated,
 for the DNS TXT record.
 See section 3.6 of RFC6376 for the record specification.
 Take the base-64 lines from the output of the second command, concatenated,
 for the DNS TXT record.
 See section 3.6 of RFC6376 for the record specification.