X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/af5614178a73fc5060e4c15064cc5855681fa02d..491fab4cccf46d85afd7bb4b58352e01e3a9923f:/doc/doc-txt/NewStuff diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff index 53bfcc179..2609d0a1f 100644 --- a/doc/doc-txt/NewStuff +++ b/doc/doc-txt/NewStuff @@ -1,4 +1,4 @@ -$Cambridge: exim/doc/doc-txt/NewStuff,v 1.121 2006/11/13 11:26:37 ph10 Exp $ +$Cambridge: exim/doc/doc-txt/NewStuff,v 1.176 2010/06/14 18:51:10 pdp Exp $ New Features in Exim -------------------- @@ -9,188 +9,448 @@ 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 4.73 +------------ + + 1. A new main configuration option, "openssl_options", is available if Exim + is built with SSL support provided by OpenSSL. The option allows + administrators to specify OpenSSL options to be used on connections; + typically this is to set bug compatibility features which the OpenSSL + developers have not enabled by default. There may be security + consequences for certain options, so these should not be changed + frivolously. + + 2. A new pipe transport option, "permit_coredumps", may help with problem + diagnosis in some scenarios. Note that Exim is typically installed as + a setuid binary, which on most OSes will inhibit coredumps by default, + so that safety mechanism would have to be overriden for this option to + be able to take effect. + + 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless + Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes + Note that this switches Exim to use a new API ("INSTREAM") and a future + release of ClamAV will remove support for the old API ("STREAM"). + + The av_scanner option, when set to "clamd", now takes an optional third + part, "local", which causes Exim to pass a filename to ClamAV instead of + the file content. This is the same behaviour as when clamd is pointed at + a Unix-domain socket. For example: + + av_scanner = clamd:192.0.2.3 1234:local + + ClamAV's ExtendedDetectionInfo response format is now handled. + + 4. There is now a -bmalware option, restricted to admin users. This option + takes one parameter, a filename, and scans that file with Exim's + malware-scanning framework. This is intended purely as a debugging aid + to ensure that Exim's scanning is working, not to replace other tools. + Note that the ACL framework is not invoked, so if av_scanner references + ACL variables without a fallback then this will fail. + + 5. There is a new expansion operator, "reverse_ip", which will reverse IP + addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples: + + ${reverse_ip:192.0.2.4} + -> 4.2.0.192 + ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3} + -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2 + + 6. There is a new ACL control called "debug", to enable debug logging. + This allows selective logging of certain incoming transactions within + production environments, with some care. It takes two options, "tag" + and "opts"; "tag" is included in the filename of the log and "opts" + is used as per the -d command-line option. Examples, which + don't all make sense in all contexts: + + control = debug + control = debug/tag=.$sender_host_address + control = debug/opts=+expand+acl + control = debug/tag=.$message_exim_id/opts=+expand + + 7. It has always been implicit in the design and the documentation that + "the Exim user" is not root. src/EDITME said that using root was + "very strongly discouraged". This is not enough to keep people from + shooting themselves in the foot in days when many don't configure Exim + themselves but via package build managers. The security consequences of + running various bits of network code are severe if there should be bugs in + them. As such, the Exim user may no longer be root. If configured + statically, Exim will refuse to build. If configured as ref:user then Exim + will exit shortly after start-up. If you must shoot yourself in the foot, + then henceforth you will have to maintain your own local patches to strip + the safeties off. + + 8. There is a new expansion operator, bool_lax{}. Where bool{} uses the ACL + condition logic to determine truth/failure and will fail to expand many + strings, bool_lax{} uses the router condition logic, where most strings + do evaluate true. + Note: bool{00} is false, bool_lax{00} is true. + + 9. Routers now support multiple "condition" tests, + +10. There is now a runtime configuration option "tcp_wrappers_daemon_name". + Setting this allows an admin to define which entry in the tcpwrappers + config file will be used to control access to the daemon. This option + is only available when Exim is built with USE_TCP_WRAPPERS. The + default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME + build option. + + +Version 4.72 +------------ + + 1. TWO SECURITY FIXES: one relating to mail-spools which are globally + writable, the other to locking of MBX folders (not mbox). + + 2. MySQL stored procedures are now supported. + + 3. The dkim_domain transport option is now a list, not a single string, and + messages will be signed for each element in the list (discarding + duplicates). + + 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups + in the presence of multiple character strings within the RR. Prior to 4.70, + only the first string would be returned. The dnsdb lookup now, by default, + preserves the pre-4.70 semantics, but also now takes an extended output + separator specification. The separator can be followed by a semicolon, to + concatenate the individual text strings together with no join character, + or by a comma and a second separator character, in which case the text + strings within a TXT record are joined on that second character. + Administrators are reminded that DNS provides no ordering guarantees + between multiple records in an RRset. For example: + + foo.example. IN TXT "a" "b" "c" + foo.example. IN TXT "d" "e" "f" + + ${lookup dnsdb{>/ txt=foo.example}} -> "a/d" + ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc" + ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f" + + +Version 4.70 / 4.71 +------------------- + + 1. Native DKIM support without an external library. + (Note that if no action to prevent it is taken, a straight upgrade will + result in DKIM verification of all signed incoming emails. See spec + for details on conditionally disabling) + + 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha). + + 3. There is now a bool{} expansion condition which maps certain strings to + true/false condition values (most likely of use in conjunction with the + and{} expansion operator). + + 4. The $spam_score, $spam_bar and $spam_report variables are now available + at delivery time. + + 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as + options, provided that Exim is invoked by an admin_user. + + 6. There is a new option gnutls_compat_mode, when linked against GnuTLS, + which increases compatibility with older clients at the cost of decreased + security. Don't set this unless you need to support such clients. + + 7. There is a new expansion operator, ${randint:...} which will produce a + "random" number less than the supplied integer. This randomness is + not guaranteed to be cryptographically strong, but depending upon how + Exim was built may be better than the most naive schemes. + + 8. Exim now explicitly ensures that SHA256 is available when linked against + OpenSSL. + + 9. The transport_filter_timeout option now applies to SMTP transports too. + + +Version 4.69 +------------ + + 1. Preliminary DKIM support in Experimental. + + +Version 4.68 +------------ + + 1. The body_linecount and body_zerocount C variables are now exported in the + local_scan API. + + 2. When a dnslists lookup succeeds, the key that was looked up is now placed + in $dnslist_matched. When the key is an IP address, it is not reversed in + this variable (though it is, of course, in the actual lookup). In simple + cases, for example: + + deny dnslists = spamhaus.example + + the key is also available in another variable (in this case, + $sender_host_address). In more complicated cases, however, this is not + true. For example, using a data lookup might generate a dnslists lookup + like this: + + deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|... + + If this condition succeeds, the value in $dnslist_matched might be + 192.168.6.7 (for example). + + 3. Authenticators now have a client_condition option. When Exim is running as + a client, it skips an authenticator whose client_condition expansion yields + "0", "no", or "false". This can be used, for example, to skip plain text + authenticators when the connection is not encrypted by a setting such as: + + client_condition = ${if !eq{$tls_cipher}{}} + + Note that the 4.67 documentation states that $tls_cipher contains the + cipher used for incoming messages. In fact, during SMTP delivery, it + contains the cipher used for the delivery. The same is true for + $tls_peerdn. + + 4. There is now a -Mvc option, which outputs a copy of the + message to the standard output, in RFC 2822 format. The option can be used + only by an admin user. + + 5. There is now a /noupdate option for the ratelimit ACL condition. It + computes the rate and checks the limit as normal, but it does not update + the saved data. This means that, in relevant ACLs, it is possible to lookup + the existence of a specified (or auto-generated) ratelimit key without + incrementing the ratelimit counter for that key. + + In order for this to be useful, another ACL entry must set the rate + for the same key somewhere (otherwise it will always be zero). + + Example: + + acl_check_connect: + # Read the rate; if it doesn't exist or is below the maximum + # we update it below + deny ratelimit = 100 / 5m / strict / noupdate + log_message = RATE: $sender_rate / $sender_rate_period \ + (max $sender_rate_limit) + + [... some other logic and tests...] + + warn ratelimit = 100 / 5m / strict / per_cmd + log_message = RATE UPDATE: $sender_rate / $sender_rate_period \ + (max $sender_rate_limit) + condition = ${if le{$sender_rate}{$sender_rate_limit}} + + accept + + 6. The variable $max_received_linelength contains the number of bytes in the + longest line that was received as part of the message, not counting the + line termination character(s). + + 7. Host lists can now include +ignore_defer and +include_defer, analagous to + +ignore_unknown and +include_unknown. These options should be used with + care, probably only in non-critical host lists such as whitelists. + + 8. There's a new option called queue_only_load_latch, which defaults true. + If set false when queue_only_load is greater than zero, Exim re-evaluates + the load for each incoming message in an SMTP session. Otherwise, once one + message is queued, the remainder are also. + + 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most + cases when an SMTP session ends without sending QUIT. However, when Exim + itself is is bad trouble, such as being unable to write to its log files, + this ACL is not run, because it might try to do things (such as write to + log files) that make the situation even worse. + + Like the QUIT ACL, this new ACL is provided to make it possible to gather + statistics. Whatever it returns (accept or deny) is immaterial. The "delay" + modifier is forbidden in this ACL. + + When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set + to a string that indicates the reason for the termination of the SMTP + connection. The possible values are: + + acl-drop Another ACL issued a "drop" command + bad-commands Too many unknown or non-mail commands + command-timeout Timeout while reading SMTP commands + connection-lost The SMTP connection has been lost + data-timeout Timeout while reading message data + local-scan-error The local_scan() function crashed + local-scan-timeout The local_scan() function timed out + signal-exit SIGTERM or SIGINT + synchronization-error SMTP synchronization error + tls-failed TLS failed to start + + In most cases when an SMTP connection is closed without having received + QUIT, Exim sends an SMTP response message before actually closing the + connection. With the exception of acl-drop, the default message can be + overridden by the "message" modifier in the NOTQUIT ACL. In the case of a + "drop" verb in another ACL, it is the message from the other ACL that is + used. + +10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of + servers with individual queries. This is done by starting the query with + "servers=x:y:z;", where each item in the list may take one of two forms: + + (1) If it is just a host name, the appropriate global option (mysql_servers + or pgsql_servers) is searched for a host of the same name, and the + remaining parameters (database, user, password) are taken from there. + + (2) If it contains any slashes, it is taken as a complete parameter set. + + The list of servers is used in exactly the same was as the global list. + Once a connection to a server has happened and a query has been + successfully executed, processing of the lookup ceases. + + This feature is intended for use in master/slave situations where updates + are occurring, and one wants to update a master rather than a slave. If the + masters are in the list for reading, you might have: + + mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw + + In an updating lookup, you could then write + + ${lookup mysql{servers=master; UPDATE ...} + + If, on the other hand, the master is not to be used for reading lookups: + + pgsql_servers = slave1/db/name/pw:slave2/db/name/pw + + you can still update the master by + + ${lookup pgsql{servers=master/db/name/pw; UPDATE ...} + +11. The message_body_newlines option (default FALSE, for backwards + compatibility) can be used to control whether newlines are present in + $message_body and $message_body_end. If it is FALSE, they are replaced by + spaces. + + +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. + + 2. When an item in a dnslists list is followed by = and & and a list of IP + addresses, the behaviour was not clear when the lookup returned more than + one IP address. This has been solved by the addition of == and =& for "all" + rather than the default "any" matching. + + 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. + + 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is + set, Exim compiles a runtime option called disable_fsync. + + 5. There is a new variable called $smtp_count_at_connection_start. + + 6. There's a new control called no_pipelining. + + 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. + + 8. The expansion of the helo_data option in the smtp transport now happens + after the connection to the server has been made. + + 9. There is a new expansion operator ${rfc2047d: that decodes strings that + are encoded as per RFC 2047. + +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. + +12. There are two new expansion conditions that iterate over a list. They are + called forany and forall. + +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). + +14. The smtp transport has a new option called hosts_avoid_pipelining. + +15. By default, exigrep does case-insensitive matches. There is now a -I option + that makes it case-sensitive. + +16. A number of new features ("addresses", "map", "filter", and "reduce") have + been added to string expansions to make it easier to process lists of + items, typically addresses. + +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. + +18. It is now possible to use newline and other control characters (those with + values less than 32, plus DEL) as separators in lists. + +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". + + +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. + 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. 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. + 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. 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. + 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, 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. - - 6. All authenticators now have a server_condition option. Previously, only - plaintext had this, and this has not changed: it must be set to the - authenticator as a server. For the others, if server_condition is set, it - is expanded if authentication is successful, and treated exactly as it is - in plaintext. This can serve as a means of adding authorization to an - authenticator. + 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, thus setting message-specific variables such - as $message_size and the header variables. The $recipients variable is - available. This feature is provided to make it easier to test expansions - that make use of these variables. However, Exim must be called by an admin - user when -Mset is used. + 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. For example: - - exim -bem /tmp/testmessage - - The file is read as a message (as if receiving a locally-submitted non-SMTP - message) before any of the test expansions are done. Thus, message-specific - variables such as $message_size and $h_from: are available. However, no - Received: header is added to the message. If the -t option is set, - recipients are read from the headers in the normal way, and are shown in - the $recipients variable. Note that recipients cannot be given on the - command line, because further arguments are taken as strings to expand - (just like -be). + -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. You can revert to - the previous behavious, that is, delay the recipient independent of the - sender, by setting address_retry_include_sender=false in the smtp - transport. However, this can lead to problems with servers that regularly - issue 4xx responses to RCPT commands. + 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. These - items may now contain arithmetic operators (plus, minus, times, divide, - remainder, negate), bitwise operators (and, or, xor, not, shift), and - parentheses. All operations are carried out using signed integer - arithmetic. Operator priorities are as in C, namely: - - (highest) not, negate - times, divide, remainder - plus, minus - shift-left, shift-right - and - xor - (lowest) or - - Binary operators with the same priority are evaluated from left to right. - For example: - - ${eval:1+1} yields 2 - ${eval:1+2*3} yields 7 - ${eval:(1+2)*3} yields 9 - ${eval:2+42%5} yields 4 - ${eval:0xc&5} yields 4 - ${eval:0xc|5} yields 13 - ${eval:0xc^5} yields 9 - ${eval:0xc>>1} yields 6 - ${eval:0xc<<1} yields 24 - ${eval:~255&0x1234} yields 4608 - ${eval:-(~255&0x1234)} yields -4608 + 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