X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/7befa435e5664f43d90bf5a2703fcf4f2a26139e..a43a27c5e355a06131c36e68a63a0609b1da8307:/doc/doc-txt/NewStuff diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff index b66cfb593..bd43aecf8 100644 --- a/doc/doc-txt/NewStuff +++ b/doc/doc-txt/NewStuff @@ -1,4 +1,4 @@ -$Cambridge: exim/doc/doc-txt/NewStuff,v 1.116 2006/10/16 13:43:21 ph10 Exp $ +$Cambridge: exim/doc/doc-txt/NewStuff,v 1.145 2007/03/13 15:32:47 ph10 Exp $ New Features in Exim -------------------- @@ -8,121 +8,461 @@ Before a formal release, there may be quite a lot of detail so that people can 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. + + 9. There is a new expansion operator ${rfc2047d: that decodes strings that + are encoded as per RFC 2047. Binary zero bytes are replaced by question + marks. Characters are converted into the character set defined by + headers_charset. Overlong RFC 2047 "words" are not recognized unless + check_rfc2047_length is set false. + +10. There is a new log selector called "pid", which causes the current process + id to be added to every log line, in square brackets, immediately after the + time and date. + +11. Exim has been modified so that it flushes SMTP output before implementing + a delay in an ACL. It also flushes the output before performing a callout, + as this can take a substantial time. These behaviours can be disabled by + obeying control = no_delay_flush or control = no_callout_flush, + respectively, at some earlier stage of the connection. The effect of the + new default behaviour is to disable the PIPELINING optimization in these + situations, in order to avoid unexpected timeouts in clients. + +12. There are two new expansion conditions that iterate over a list. They are + called forany and forall, and they are used like this: + + ${if forany{}{}{}{}} + ${if forall{}{}{}{}} + + The first argument is expanded, and the result is treated as a list. By + default, the list separator is a colon, but it can be changed by the normal + method. The second argument is interpreted as a condition that is to be + applied to each item in the list in turn. During the interpretation of the + condition, the current list item is placed in a variable called $item. + + - For forany, interpretation stops if the condition is true for any item, + and the yes-string is then expanded. If the condition is false for all + items in the list, the no-string is expanded. + + - For forall, interpration stops if the condition is false for any item, + and the no-string is then expanded. If the condition is true for all + items in the list, the yes-string is expanded. + + Note that negation of forany means that the condition must be false for all + items for the overall condition to succeed, and negation of forall means + that the condition must be false for at least one item. + + In this example, the list separator is changed to a comma: + + ${if forany{<, $recipients}{match{$item}{^user3@}}{yes}{no}} + + Outside a forany/forall condition, the value of $item is an empty string. + Its value is saved and restored while forany/forall is being processed, to + enable these expansion items to be nested. + +13. There's a new global option called dsn_from that can be used to vary the + contents of From: lines in bounces and other automatically generated + messages ("delivery status notifications" - hence the name of the option). + The default setting is: + + dsn_from = Mail Delivery System + + The value is expanded every time it is needed. If the expansion fails, a + panic is logged, and the default setting is used. + +14. The smtp transport has a new option called hosts_avoid_pipelining. It can + be used to suppress the use of PIPELINING to certain hosts, while still + supporting the other SMTP extensions (cf hosts_avoid_tls). + +15. By default, exigrep does case-insensitive matches. There is now a -I option + that makes it case-sensitive. This may give a performance improvement when + searching large log files. Without -I, the Perl pattern matches use the /i + option; with -I they don't. In both cases it is possible to change the case + sensitivity within the pattern using (?i) or (?-i). + +16. A number of new features have been added to string expansions to make it + easier to process lists of items, typically addresses. These are as + follows: + + * ${addresses:} + + The string (after expansion) is interpreted as a list of addresses in RFC + 2822 format, such as can be found in a To: or Cc: header line. The + operative address (local-part@domain) is extracted from each item, and the + result of the expansion is a colon-separated list, with appropriate + doubling of colons should any happen to be present in the email addresses. + Syntactically invalid RFC2822 address items are omitted from the output. + + It is possible to specify a character other than colon for the output + separator by starting the string with > followed by the new separator + character. For example: + + ${addresses:>& The Boss , sec@base.ment (dogsbody)} + + expands to "ceo@up.stairs&sec@base.ment". Compare ${address (singular), + which extracts the working address from a single RFC2822 address. + + * ${map{}{}} + + After expansion, is interpreted as a list, colon-separated by + default, but the separator can be changed in the usual way. For each item + in this list, its value is place in $item, and then is expanded + and added to the output as an item in a new list. The separator used for + the output list is the same as the one used for the input, but is not + included in the output. For example: + + ${map{a:b:c}{[$item]}} ${map{<- x-y-z}{($item)}} + + expands to "[a]:[b]:[c] (x)-(y)-(z)". At the end of the expansion, the + value of $item is restored to what it was before. + + * ${filter{}{}} + + After expansion, is interpreted as a list, colon-separated by + default, but the separator can be changed in the usual way. For each item + in this list, its value is place in $item, and then the condition is + evaluated. If the condition is true, $item is added to the output as an + item in a new list; if the condition is false, the item is discarded. The + separator used for the output list is the same as the one used for the + input, but is not included in the output. For example: + + ${filter{a:b:c}{!eq{$item}{b}} + + yields "a:c". At the end of the expansion, the value of $item is restored + to what it was before. + + * ${reduce{}{}{}} + + The ${reduce expansion operation reduces a list to a single, scalar string. + After expansion, is interpreted as a list, colon-separated by + default, but the separator can be changed in the usual way. Then + is expanded and assigned to the $value variable. After this, each item in + the list is assigned to $item in turn, and is expanded + for each of them. The result of that expansion is assigned to $value before + the next iteration. When the end of the list is reached, the final value of + $value is added to the expansion string. The ${reduce expansion item can be + used in a number of ways. For example, to add up a list of numbers: + + ${reduce {<, 1,2,3}{0}{${eval:$value+$item}}} + + The result of that expansion would be "6". The maximum of a list of numbers + can be found: + + ${reduce {3:0:9:4:6}{0}{${if >{$item}{$value}{$item}{$value}}}} + + At the end of a ${reduce expansion, the values of $item and $value is + restored to what they were before. + +17. There's a new ACL modifier called "continue". It does nothing of itself, + and processing of the ACL always continues with the next condition or + modifier. It is provided so that the side effects of expanding its argument + can be used. Typically this would be for updating a database. It is really + just a syntactic tidiness, because the following two lines have the same + effect: + + continue = + condition = ${if eq{0}{}{true}{true}} + +18. It is now possible to use newline and other control characters (those with + values less than 32, plus DEL) as separators in lists. Such separators must + be provided literally at the time the list is processed, but the string + expansion that happens first means that you can write them using normal + escape sequences. For example, if a new-line separated list of domains is + generated by a lookup, you can now process it directly by a line such as + this: + + domains = <\n ${lookup mysql{.....}} + + This avoids having to change the list separator in such data. Unlike + printing character separators, which can be included in list items by + doubling, it is not possible to include a control character as data when it + is set as the separator. Two such characters in succession are interpreted + as enclosing an empty list item. + +19. The exigrep utility now has a -v option, which inverts the matching + condition. + +20. The host_find_failed option in the manualroute router can now be set to + "ignore". This causes it to completely ignore a host whose IP address + cannot be found. If all the hosts in the list are ignored, the behaviour is + controlled by the new host_all_ignored option, which takes the same values + as host_find_failed, except that it cannot be set to "ignore". Its default + is "defer". + + +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 ------------ -1. ACL variables can now be given arbitrary names, as long as they start with - "acl_c" or "acl_m" (for connection variables and message variables), are - at least six characters long, with the sixth character being either a digit - or an underscore. The rest of the name can contain alphanumeric characters - and underscores. This is a compatible change because the old set of - variables such as acl_m12 are a subset of the allowed names. There may now - be any number of ACL variables. For example: - - set acl_c13 = value for original ACL variable - set acl_c13b = whatever - set acl_m_foo = something - - What happens if a syntactically valid but undefined ACL variable is - referenced depends on the setting of the strict_acl_vars option. If it is - false (the default), an empty string is substituted; if it is true, an error - is generated. This affects all ACL variables, including the "old" ones such - as acl_c4. (Previously there wasn't the concept of an undefined ACL - variable.) - - The implementation has been done in such a way that spool files containing - ACL variable settings written by previous releases of Exim are compatible - and can be read by the new release. If only the original numeric names are - used, spool files written by the new release can be read by earlier - releases. - -2. There is a new ACL modifier called log_reject_target. It makes it possible - to specify which logs are used for messages about ACL rejections. Its - argument is a list of words which can be "main", "reject", or "panic". The - default is "main:reject". The list may be empty, in which case a rejection - is not logged at all. For example, this ACL fragment writes no logging - information when access is denied: - - deny - log_reject_target = - - The modifier can be used in SMTP and non-SMTP ACLs. It applies to both - permanent and temporary rejections. - -3. There is a new authenticator called "dovecot". This is an interface to the - authentication facility of the Dovecot POP/IMAP server, which can support a - number of authentication methods. If you are using Dovecot to authenticate - POP/IMAP clients, it might be helpful to use the same mechanisms for SMTP - authentication. This is a server authenticator only. The only option is - server_socket, which must specify the socket which is the interface to - Dovecot authentication. The public_name option must specify an - authentication mechanism that Dovecot is configured to support. You can have - several authenticators for different mechanisms. For example: - - dovecot_plain: - driver = dovecot - public_name = PLAIN - server_name = /var/run/dovecot/auth-client - server_setid = $auth1 - - dovecot_ntlm: - driver = dovecot - public_name = NTLM - server_name = /var/run/dovecot/auth-client - server_setid = $auth1 - - If the SMTP connection is encrypted, or if $sender_host_address is equal to - $interface_address (that is, the connection is local), the "secured" option - is passed in the Dovecot authentication command. If, for a TLS connection, a - client certificate has been verified, the "valid-client-cert" option is - passed. - -4. The variable $message_headers_raw provides a concatenation of all the - messages's headers without any decoding. This is in contrast to - $message_headers, which does RFC2047 decoding on the header contents. - -5. In a DNS black list, when the facility for restricting the matching IP - values is used, the text from the TXT record that is set in $dnslist_text - may not reflect the true reason for rejection. This happens when lists are - merged and the IP address in the A record is used to distinguish them; - unfortunately there is only one TXT record. One way round this is not to use - merged lists, but that can be inefficient because it requires multiple DNS - lookups where one would do in the vast majority of cases when the host of - interest is not on any of the lists. - - A less inefficient way of solving this problem has now been implemented. If - two domain names, comma-separated, are given, the second is used first to do - an initial check, making use of any IP value restrictions that are set. If - there is a match, the first domain is used, without any IP value - restrictions, to get the TXT record. As a byproduct of this, there is also a - check that the IP being tested is indeed on the first list. The first domain - is the one that is put in $dnslist_domain. For example: - - reject message = rejected because $sender_ip_address is blacklisted \ - at $dnslist_domain\n$dnslist_text - dnslists = sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \ - dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10 - - For the first blacklist item, this starts by doing a lookup in - sbl-xbl.spamhaus.org and testing for a 127.0.0.2 return. If there is a - match, it then looks in sbl.spamhaus.org, without checking the return value, - and as long as something is found, it looks for the corresponding TXT - record. If there is no match in sbl-xbl.spamhaus.org, nothing more is done. - The second blacklist item is processed similarly. - - If you are interested in more than one merged list, the same list must be - given several times, but because the results of the DNS lookups are cached, - the DNS calls themselves are not repeated. For example: - - reject dnslists = http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \ - socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3 : \ - misc.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.4 : \ - dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10 - - In this case there is a lookup in dnsbl.sorbs.net, and if none of the IP - values matches (or if no record is found), this is the only lookup that is - done. Only if there is a match is one of the more specific lists consulted. + 1. ACL variables can now be given arbitrary names, as long as they start with + "acl_c" or "acl_m" (for connection variables and message variables), are at + least six characters long, with the sixth character being either a digit or + an underscore. + + 2. There is a new ACL modifier called log_reject_target. It makes it possible + to specify which logs are used for messages about ACL rejections. + + 3. There is a new authenticator called "dovecot". This is an interface to the + authentication facility of the Dovecot POP/IMAP server, which can support a + number of authentication methods. + + 4. The variable $message_headers_raw provides a concatenation of all the + messages's headers without any decoding. This is in contrast to + $message_headers, which does RFC2047 decoding on the header contents. + + 5. In a DNS black list, if two domain names, comma-separated, are given, the + second is used first to do an initial check, making use of any IP value + restrictions that are set. If there is a match, the first domain is used, + without any IP value restrictions, to get the TXT record. + + 6. All authenticators now have a server_condition option. + + 7. There is a new command-line option called -Mset. It is useful only in + conjunction with -be (that is, when testing string expansions). It must be + followed by a message id; Exim loads the given message from its spool + before doing the expansions. + + 8. Another similar new command-line option is called -bem. It operates like + -be except that it must be followed by the name of a file that contains a + message. + + 9. When an address is delayed because of a 4xx response to a RCPT command, it + is now the combination of sender and recipient that is delayed in + subsequent queue runs until its retry time is reached. + +10. Unary negation and the bitwise logical operators and, or, xor, not, and + shift, have been added to the eval: and eval10: expansion items. + +11. The variables $interface_address and $interface_port have been renamed + as $received_ip_address and $received_port, to make it clear that they + relate to message reception rather than delivery. (The old names remain + available for compatibility.) + +12. The "message" modifier can now be used on "accept" and "discard" acl verbs + to vary the message that is sent when an SMTP command is accepted. Version 4.63