-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.125 2006/12/20 09:44:37 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.132 2007/01/30 15:10:58 ph10 Exp $
New Features in Exim
--------------------
test from the snapshots or the CVS before the documentation is updated. Once
the documentation is updated, this file is reduced to a short list.
+Version 4.67
+------------
+
+ 1. There is a new log selector called smtp_no_mail, which is not included in
+ the default setting. When it is set, a line is written to the main log
+ whenever an accepted SMTP connection terminates without having issued a
+ MAIL command. This includes both the case when the connection is dropped,
+ and the case when QUIT is used. Note that it does not include cases where
+ the connection is rejected right at the start (by an ACL, or because there
+ are too many connections, or whatever). These cases already have their own
+ log lines.
+
+ The log line that is written contains the identity of the client in the
+ usual way, followed by D= and a time, which records the duration of the
+ connection. If the connection was authenticated, this fact is logged
+ exactly as it is for an incoming message, with an A= item. If the
+ connection was encrypted, CV=, DN=, and X= items may appear as they do for
+ an incoming message, controlled by the same logging options.
+
+ Finally, if any SMTP commands were issued during the connection, a C= item
+ is added to the line, listing the commands that were used. For example,
+
+ C=EHLO,QUIT
+
+ shows that the client issued QUIT straight after EHLO. If there were fewer
+ than 20 commands, they are all listed. If there were more than 20 commands,
+ the last 20 are listed, preceded by "...". However, with the default
+ setting of 10 for smtp_accep_max_nonmail, the connection will in any case
+ be aborted before 20 non-mail commands are processed.
+
+ 2. When an item in a dnslists list is followed by = and & and a list of IP
+ addresses, in order to restrict the match to specific results from the DNS
+ lookup, the behaviour was not clear when the lookup returned more than one
+ IP address. For example, consider the condition
+
+ dnslists = a.b.c=127.0.0.1
+
+ What happens if the DNS lookup for the incoming IP address yields both
+ 127.0.0.1 and 127.0.0.2 by means of two separate DNS records? Is the
+ condition true because at least one given value was found, or is it false
+ because at least one of the found values was not listed? And how does this
+ affect negated conditions?
+
+ The behaviour of = and & has not been changed; however, the text below
+ documents it more clearly. In addition, two new additional conditions (==
+ and =&) have been added, to permit the "other" behaviour to be configured.
+
+ A DNS lookup may yield more than one record. Thus, the result of the lookup
+ for a dnslists check may yield more than one IP address. The question then
+ arises as to whether all the looked up addresses must be listed, or whether
+ just one is good enough. Both possibilities are provided for:
+
+ . If = or & is used, the condition is true if any one of the looked up
+ IP addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c=127.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ true because 127.0.0.1 matches.
+
+ . If == or =& is used, the condition is true only if every one of the
+ looked up IP addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c==127.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ false because 127.0.0.2 is not listed. You would need to have
+
+ dnslists = a.b.c==127.0.0.1,127.0.0.2
+
+ for the condition to be true.
+
+ When ! is used to negate IP address matching, it inverts the result, giving
+ the precise opposite of the behaviour above. Thus:
+
+ . If != or !& is used, the condition is true if none of the looked up IP
+ addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c!&0.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ false because 127.0.0.1 matches.
+
+ . If !== or !=& is used, the condition is true there is at least one looked
+ up IP address that does not match. Consider:
+
+ dnslists = a.b.c!=&0.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ true, because 127.0.0.2 does not match. You would need to have
+
+ dnslists = a.b.c!=&0.0.0.1,0.0.0.2
+
+ for the condition to be false.
+
+ When the DNS lookup yields only a single IP address, there is no difference
+ between = and == and between & and =&.
+
+ 3. Up till now, the only control over which cipher suites GnuTLS uses has been
+ for the cipher algorithms. New options have been added to allow some of the
+ other parameters to be varied. Here is complete documentation for the
+ available features:
+
+ GnuTLS allows the caller to specify separate lists of permitted key
+ exchange methods, main cipher algorithms, and MAC algorithms. These may be
+ used in any combination to form a specific cipher suite. This is unlike
+ OpenSSL, where complete cipher names can be passed to its control function.
+ GnuTLS also allows a list of acceptable protocols to be supplied.
+
+ For compatibility with OpenSSL, the tls_require_ciphers option can be set
+ to complete cipher suite names such as RSA_ARCFOUR_SHA, but for GnuTLS this
+ option controls only the cipher algorithms. Exim searches each item in the
+ list for the name of an available algorithm. For example, if the list
+ contains RSA_AES_SHA, then AES is recognized, and the behaviour is exactly
+ the same as if just AES were given.
+
+ There are additional options called gnutls_require_kx, gnutls_require_mac,
+ and gnutls_require_protocols that can be used to restrict the key exchange
+ methods, MAC algorithms, and protocols, respectively. These options are
+ ignored if OpenSSL is in use.
+
+ All four options are available as global options, controlling how Exim
+ behaves as a server, and also as options of the smtp transport, controlling
+ how Exim behaves as a client. All the values are string expanded. After
+ expansion, the values must be colon-separated lists, though the separator
+ can be changed in the usual way.
+
+ Each of the four lists starts out with a default set of algorithms. If the
+ first item in one of the "require" options does _not_ start with an
+ exclamation mark, all the default items are deleted. In this case, only
+ those that are explicitly specified can be used. If the first item in one
+ of the "require" items _does_ start with an exclamation mark, the defaults
+ are left on the list.
+
+ Then, any item that starts with an exclamation mark causes the relevant
+ entry to be removed from the list, and any item that does not start with an
+ exclamation mark causes a new entry to be added to the list. Unrecognized
+ items in the list are ignored. Thus:
+
+ tls_require_ciphers = !ARCFOUR
+
+ allows all the defaults except ARCFOUR, whereas
+
+ tls_require_ciphers = AES : 3DES
+
+ allows only cipher suites that use AES or 3DES. For tls_require_ciphers
+ the recognized names are AES_256, AES_128, AES (both of the preceding),
+ 3DES, ARCFOUR_128, ARCFOUR_40, and ARCFOUR (both of the preceding). The
+ default list does not contain all of these; it just has AES_256, AES_128,
+ 3DES, and ARCFOUR_128.
+
+ For gnutls_require_kx, the recognized names are DHE_RSA, RSA (which
+ includes DHE_RSA), DHE_DSS, and DHE (which includes both DHE_RSA and
+ DHE_DSS). The default list contains RSA, DHE_DSS, DHE_RSA.
+
+ For gnutls_require_mac, the recognized names are SHA (synonym SHA1), and
+ MD5. The default list contains SHA, MD5.
+
+ For gnutls_require_protocols, the recognized names are TLS1 and SSL3.
+ The default list contains TLS1, SSL3.
+
+ In a server, the order of items in these lists is unimportant. The server
+ will advertise the availability of all the relevant cipher suites. However,
+ in a client, the order in the tls_require_ciphers list specifies a
+ preference order for the cipher algorithms. The first one in the client's
+ list that is also advertised by the server is tried first.
+
+ 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. You must
+ not set this option unless you really, really, really understand what you
+ are doing. No pre-compiled distributions of Exim should ever set this
+ option. When it is set, Exim compiles a runtime option called
+ disable_fsync. If this is set true, Exim no longer calls fsync() to force
+ updated files' data to be written to disc. Unexpected events such as
+ crashes and power outages may cause data to be lost or scrambled. Beware.
+
+ When ENABLE_DISABLE_FSYNC is not set, a reference to disable_fsync in a
+ runtime configuration generates an "unknown option" error.
+
+ 5. There is a new variable called $smtp_count_at_connection_start. The name
+ is deliberately long, in order to emphasize what the contents are. This
+ variable is set greater than zero only in processes spawned by the Exim
+ daemon for handling incoming SMTP connections. When the daemon accepts a
+ new connection, it increments this variable. A copy of the variable is
+ passed to the child process that handles the connection, but its value is
+ fixed, and never changes. It is only an approximation of how many incoming
+ connections there actually are, because many other connections may come and
+ go while a single connection is being processed. When a child process
+ terminates, the daemon decrements the variable.
+
+ 6. There's a new control called no_pipelining, which does what its name
+ suggests. It turns off the advertising of the PIPELINING extension to SMTP.
+ To be useful, this control must be obeyed before Exim sends its response to
+ an EHLO command. Therefore, it should normally appear in an ACL controlled
+ by acl_smtp_connect or acl_smtp_helo.
+
+ 7. There are two new variables called $sending_ip_address and $sending_port.
+ These are set whenever an SMTP connection to another host has been set up,
+ and they contain the IP address and port of the local interface that is
+ being used. They are of interest only on hosts that have more than on IP
+ address that want to take on different personalities depending on which one
+ is being used.
+
+ 8. The expansion of the helo_data option in the smtp transport now happens
+ after the connection to the server has been made. This means that it can
+ use the value of $sending_ip_address (see 7 above) to vary the text of the
+ message. For example, if you want the string that is used for helo_data to
+ be obtained by a DNS lookup of the interface address, you could use this:
+
+ helo_data = ${lookup dnsdb{ptr=$sending_ip_address}{$value}\
+ {$primary_hostname}}
+
+ The use of helo_data applies both to sending messages and when doing
+ callouts.
+
+
+Version 4.66
+------------
+
+No new features were added to 4.66.
+
+
+Version 4.65
+------------
+
+No new features were added to 4.65.
+
Version 4.64
------------
git://git.exim.org / exim.git / blobdiff