X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/e3a311ba37578327f16036af35406f1c4f5806bf..b8dc3e4a6769d5b233b1117f16b334a583716b10:/doc/doc-txt/NewStuff?ds=inline diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff index bddf5b827..6fa8b4b83 100644 --- a/doc/doc-txt/NewStuff +++ b/doc/doc-txt/NewStuff @@ -1,4 +1,4 @@ -$Cambridge: exim/doc/doc-txt/NewStuff,v 1.55 2005/07/23 20:59:16 tom Exp $ +$Cambridge: exim/doc/doc-txt/NewStuff,v 1.103 2006/06/27 14:34:26 ph10 Exp $ New Features in Exim -------------------- @@ -8,588 +8,89 @@ but have not yet made it into the main manual (which is most conveniently updated when there is a relatively large batch of changes). The doc/ChangeLog file contains a listing of all changes, including bug fixes. -Exim version 4.53 ------------------ - -TK/01 Added the "success_on_redirect" address verification option. When an - address generates new addresses during routing, Exim will abort - verification with "success" when more than one address has been - generated, but continue to verify a single new address. The latter - does not happen when the new "success_on_redirect" option is set, like - - require verify = recipient/success_on_redirect/callout=10s - - In that case, verification will succeed when a router generates a new - address. - - -Exim version 4.52 ------------------ - -TF/01 Support for checking Client SMTP Authorization has been added. CSA is a - system which allows a site to advertise which machines are and are not - permitted to send email. This is done by placing special SRV records in - the DNS, which are looked up using the client's HELO domain. At this - time CSA is still an Internet-Draft. - - Client SMTP Authorization checks are performed by the ACL condition - verify=csa. This will fail if the client is not authorized. If there is - a DNS problem, or if no valid CSA SRV record is found, or if the client - is authorized, the condition succeeds. These three cases can be - distinguished using the expansion variable $csa_status, which can take - one of the values "fail", "defer", "unknown", or "ok". The condition - does not itself defer because that would be likely to cause problems - for legitimate email. - - The error messages produced by the CSA code include slightly more - detail. If $csa_status is "defer" this may be because of problems - looking up the CSA SRV record, or problems looking up the CSA target - address record. There are four reasons for $csa_status being "fail": - the client's host name is explicitly not authorized; the client's IP - address does not match any of the CSA target IP addresses; the client's - host name is authorized but it has no valid target IP addresses (e.g. - the target's addresses are IPv6 and the client is using IPv4); or the - client's host name has no CSA SRV record but a parent domain has - asserted that all subdomains must be explicitly authorized. - - The verify=csa condition can take an argument which is the domain to - use for the DNS query. The default is verify=csa/$sender_helo_name. - - This implementation includes an extension to CSA. If the query domain - is an address literal such as [192.0.2.95], or if it is a bare IP - address, Exim will search for CSA SRV records in the reverse DNS as if - the HELO domain was e.g. 95.2.0.192.in-addr.arpa. Therefore it is - meaningful to say, for example, verify=csa/$sender_host_address - in - fact, this is the check that Exim performs if the client does not say - HELO. This extension can be turned off by setting the main - configuration option dns_csa_use_reverse = false. - - If a CSA SRV record is not found for the domain itself, then a search - is performed through its parent domains for a record which might be - making assertions about subdomains. The maximum depth of this search is - limited using the main configuration option dns_csa_search_limit, which - takes the value 5 by default. Exim does not look for CSA SRV records in - a top level domain, so the default settings handle HELO domains as long - as seven (hostname.five.four.three.two.one.com) which encompasses the - vast majority of legitimate HELO domains. - - The dnsdb lookup also has support for CSA. Although dnsdb already - supports SRV lookups, this is not sufficient because of the extra - parent domain search behaviour of CSA, and (as with PTR lookups) - dnsdb also turns IP addresses into lookups in the reverse DNS space. - The result of ${lookup dnsdb {csa=$sender_helo_name} } has two - space-separated fields: an authorization code and a target host name. - The authorization code can be "Y" for yes, "N" for no, "X" for explicit - authorization required but absent, or "?" for unknown. - -PH/01 The amount of output produced by the "make" process has been reduced, - because the compile lines are often rather long, making it all pretty - unreadable. The new style is along the lines of the 2.6 Linux kernel: - just a short line for each module that is being compiled or linked. - However, it is still possible to get the full output, by calling "make" - like this: - - FULLECHO='' make -e - - The value of FULLECHO defaults to "@", the flag character that suppresses - command reflection in "make". When you ask for the full output, it is - given in addition to the the short output. - -TF/02 There have been two changes concerned with submission mode: - - Until now submission mode always left the return path alone, whereas - locally-submitted messages from untrusted users have the return path - fixed to the user's email address. Submission mode now fixes the return - path to the same address as is used to create the Sender: header. If - /sender_retain is specified then both the Sender: header and the return - path are left alone. - - Note that the changes caused by submission mode take effect after the - predata ACL. This means that any sender checks performed before the - fix-ups will use the untrusted sender address specified by the user, not - the trusted sender address specified by submission mode. Although this - might be slightly unexpected, it does mean that you can configure ACL - checks to spot that a user is trying to spoof another's address, for - example. - - There is also a new /name= option for submission mode which allows you - to specify the user's full name to be included in the Sender: header. - For example: - - accept authenticated = * - control = submission/name=${lookup {$authenticated_id} \ - lsearch {/etc/exim/namelist} } - - The namelist file contains entries like - - fanf: Tony Finch - - And the resulting Sender: header looks like - - Sender: Tony Finch - -TF/03 The control = fakereject ACL modifier now has a fakedefer counterpart, - which works in exactly the same way except it causes a fake SMTP 450 - response after the message data instead of a fake SMTP 550 response. - You must take care when using fakedefer because it will cause messages - to be duplicated when the sender retries. Therefore you should not use - fakedefer if the message will be delivered normally. - -TF/04 There is a new ratelimit ACL condition which can be used to measure - and control the rate at which clients can send email. This is more - powerful than the existing smtp_ratelimit_* options, because those - options only control the rate of commands in a single SMTP session, - whereas the new ratelimit condition works across all connections - (concurrent and sequential) to the same host. - - The syntax of the ratelimit condition is: - - ratelimit = /

/ / - - If the average client sending rate is less than m messages per time - period p then the condition is false, otherwise it is true. - - The parameter p is the smoothing time constant, in the form of an Exim - time interval e.g. 8h for eight hours. A larger time constant means it - takes Exim longer to forget a client's past behaviour. The parameter m is - the maximum number of messages that a client can send in a fast burst. By - increasing both m and p but keeping m/p constant, you can allow a client - to send more messages in a burst without changing its overall sending - rate limit. Conversely, if m and p are both small then messages must be - sent at an even rate. - - The key is used to look up the data used to calcluate the client's - average sending rate. This data is stored in a database maintained by - Exim in its spool directory alongside the retry database etc. For - example, you can limit the sending rate of each authenticated user, - independent of the computer they are sending from, by setting the key - to $authenticated_id. The default key is $sender_host_address. - - Each ratelimit condition can have up to two options. The first option - specifies what Exim measures the rate of, and the second specifies how - Exim handles excessively fast clients. - - The per_mail option means that it measures the client's rate of sending - messages. This is the default if none of the per_* options is specified. - - The per_conn option means that it measures the client's connection rate. - - The per_byte option limits the sender's email bandwidth. Note that it - is best to use this option in the DATA ACL; if it is used in an earlier - ACL it relies on the SIZE parameter on the MAIL command, which may be - inaccurate or completely missing. You can follow the limit m in the - configuration with K, M, or G to specify limits in kilobytes, - megabytes, or gigabytes respectively. - - The per_cmd option means that Exim recomputes the rate every time the - condition is processed, which can be used to limit the SMTP command rate. - The alias per_rcpt is provided for use in the RCPT ACL instead of per_cmd - to make it clear that the effect is to limit the rate at which recipients - are accepted. Note that in this case the rate limiting engine will see a - message with many recipients as a large high-speed burst. - - If a client's average rate is greater than the maximum, the rate - limiting engine can react in two possible ways, depending on the - presence of the strict or leaky options. This is independent of the - other counter-measures (e.g. rejecting the message) that may be - specified by the rest of the ACL. The default mode is leaky, which - avoids a sender's over-aggressive retry rate preventing it from getting - any email through. - - The strict option means that the client's recorded rate is always - updated. The effect of this is that Exim measures the client's average - rate of attempts to send email, which can be much higher than the - maximum. If the client is over the limit it will be subjected to - counter-measures until it slows down below the maximum rate. - - The leaky option means that the client's recorded rate is not updated - if it is above the limit. The effect of this is that Exim measures the - client's average rate of successfully sent email, which cannot be - greater than the maximum. If the client is over the limit it will - suffer some counter-measures, but it will still be able to send email - at the configured maximum rate, whatever the rate of its attempts. - - As a side-effect, the ratelimit condition will set the expansion - variables $sender_rate containing the client's computed rate, - $sender_rate_limit containing the configured value of m, and - $sender_rate_period containing the configured value of p. - - Exim's other ACL facilities are used to define what counter-measures - are taken when the rate limit is exceeded. This might be anything from - logging a warning (e.g. while measuring existing sending rates in order - to define our policy), through time delays to slow down fast senders, - up to rejecting the message. For example, - - # Log all senders' rates - warn - ratelimit = 0 / 1h / strict - log_message = \ - Sender rate $sender_rate > $sender_rate_limit / $sender_rate_period - - # Slow down fast senders - warn - ratelimit = 100 / 1h / per_rcpt / strict - delay = ${eval: 10 * ($sender_rate - $sender_rate_limit) } - - # Keep authenticated users under control - deny - ratelimit = 100 / 1d / strict / $authenticated_id - - # System-wide rate limit - defer - message = Sorry, too busy. Try again later. - ratelimit = 10 / 1s / $primary_hostname - - # Restrict incoming rate from each host, with a default rate limit - # set using a macro and special cases looked up in a table. - defer - message = Sender rate $sender_rate exceeds \ - $sender_rate_limit messages per $sender_rate_period - ratelimit = ${lookup {$sender_host_address} \ - cdb {DB/ratelimits.cdb} \ - {$value} {RATELIMIT} } - - Warning: if you have a busy server with a lot of ratelimit tests, - especially with the per_rcpt option, you may suffer from a performance - bottleneck caused by locking on the ratelimit hints database. Apart from - making your ACLs less complicated, you can reduce the problem by using a - RAM disk for Exim's hints directory, /var/spool/exim/db/. However this - means that Exim will lose its hints data after a reboot (including retry - hints, the callout cache, and ratelimit data). - -TK/01 Added an 'spf' lookup type that will return an SPF result for a given - email address (the key) and an IP address (the database): - - ${lookup {tom@duncanthrax.net} spf{217.115.139.137}} - - The lookup will return the same result strings as they can appear in - $spf_result (pass,fail,softfail,neutral,none,err_perm,err_temp). The - lookup is armored in EXPERIMENTAL_SPF. Currently, only IPv4 addresses - are supported. - - Patch submitted by Chris Webb . - -PH/02 There's a new verify callout option, "fullpostmaster", which first acts - as "postmaster" and checks the recipient . If that - fails, it tries just , without a domain, in accordance with - the specification in RFC 2821. - -PH/03 The action of the auto_thaw option has been changed. It no longer applies - to frozen bounce messages. - -TK/02 There are two new expansion items to help with the implementation of - the BATV "prvs" scheme in an Exim configuration: - - - ${prvs {

}{}{[KEYNUM]}} - - The "prvs" expansion item takes three arguments: A qualified RFC2821 - email address, a key and an (optional) key number. All arguments are - expanded before being used, so it is easily possible to lookup a key - and key number using the address as the lookup key. The key number is - optional and defaults to "0". The item will expand to a "prvs"-signed - email address, to be typically used with the "return_path" option on - a smtp transport. The decision if BATV should be used with a given - sender/recipient pair should be done on router level, to avoid having - to set "max_rcpt = 1" on the transport. - - - ${prvscheck {
}{}{}} - - The "prvscheck" expansion item takes three arguments. Argument 1 is - expanded first. When the expansion does not yield a SYNTACTICALLY - valid "prvs"-scheme address, the whole "prvscheck" item expands to - the empty string. If
is a "prvs"-encoded address after - expansion, two expansion variables are set up: - - $prvscheck_address Contains the "prvs"-decoded version of - the address from argument 1. - - $prvscheck_keynum Contains the key number extracted from - the "prvs"-address in argument 1. - - These two variables can be used in the expansion code of argument 2 - to retrieve the . The VALIDITY of the "prvs"-signed address - is then checked. The result is stored in yet another expansion - variable: - - $prvscheck_result Contains the result of a "prvscheck" - expansion: Unset (the empty string) for - failure, "1" for success. - - The "prvscheck" expansion expands to the empty string if
- is not a SYNTACTICALLY valid "prvs"-scheme address. Otherwise, - argument 3 defines what "prvscheck" expands to: If argument 3 - is the empty string, "prvscheck" expands to the decoded version - of the address (no matter if it is CRYPTOGRAPHICALLY valid or not). - If argument 3 expands to a non-empty string, "prvscheck" expands - to that string. - - - Usage example - ------------- - - Macro: - - PRVSCHECK_SQL = ${lookup mysql{SELECT secret FROM batv_prvs WHERE \ - sender='${quote_mysql:$prvscheck_address}'}{$value}} - - RCPT ACL: - - # Bounces: drop unsigned addresses for BATV senders - deny message = This address does not send an unsigned reverse path. - senders = : - recipients = +batv_recipients +Version 4.63 +------------ - # Bounces: In case of prvs-signed address, check signature. - deny message = Invalid reverse path signature. - senders = : - condition = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{1}} - !condition = $prvscheck_result +1. There is a new Boolean option called filter_prepend_home for the redirect + router. It defaults true, for backward compatibility. If a "save" command in + an Exim filter has a relative path for its argument, and $home is defined, + it is automatically prepended to the relative path. This action can now be + prevented by setting filter_prepend_home false. - Top-Level Router: - batv_redirect: - driver = redirect - data = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{}} +Version 4.62 +------------ - Transport (referenced by router that makes decision if - BATV is applicable): +1. The ${readsocket expansion item now supports Internet domain sockets as well + as Unix domain sockets. If the first argument begins "inet:", it must be of + the form "inet:host:port". The port is mandatory; it may be a number or the + name of a TCP port in /etc/services. The host may be a name, or it may be an + IP address. An ip address may optionally be enclosed in square brackets. + This is best for IPv6 addresses. For example: - external_smtp_batv: - driver = smtp - return_path = ${prvs {$return_path} \ - {${lookup mysql{SELECT \ - secret FROM batv_prvs WHERE \ - sender='${quote_mysql:$sender_address}'} \ - {$value}fail}}} + ${readsocket{inet:[::1]:1234}{}... -PH/04 There are two new options that control the retrying done by the daemon - at startup when it cannot immediately bind a socket (typically because - the socket is already in use). The default values reproduce what were - built-in constants previously: daemon_startup_retries defines the number - of retries after the first failure (default 9); daemon_startup_sleep - defines the length of time to wait between retries (default 30s). + Only a single host name may be given, but if looking it up yield more than + one IP address, they are each tried in turn until a connection is made. Once + a connection has been made, the behaviour is as for ${readsocket with a Unix + domain socket. -PH/05 There is now a new ${if condition called "match_ip". It is similar to - match_domain, etc. It must be followed by two argument strings. The first - (after expansion) must be an IP address or an empty string. The second - (after expansion) is a restricted host list that can match only an IP - address, not a host name. For example: +2. If a redirect router sets up file or pipe deliveries for more than one + incoming address, and the relevant transport has batch_max set greater than + one, a batch delivery now occurs. - ${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}} +3. The appendfile transport has a new option called maildirfolder_create_regex. + Its value is a regular expression. For a maildir delivery, this is matched + against the maildir directory; if it matches, Exim ensures that a + maildirfolder file is created alongside the new, cur, and tmp directories. - The specific types of host list item that are permitted in the list are - shown below. Consult the manual section on host lists for further - details. - . An IP address, optionally with a CIDR mask. +Version 4.61 +------------ - . A single asterisk matches any IP address. +The documentation is up-to-date for the 4.61 release. Major new features since +the 4.60 release are: - . An empty item matches only if the IP address is empty. This could be - useful for testing for a locally submitted message or one from specific - hosts in a single test such as +. An option called disable_ipv6, to disable the use of IPv6 completely. - ${if match_ip{$sender_host_address}{:4.3.2.1:...}{...}{...}} +. An increase in the number of ACL variables to 20 of each type. - where the first item in the list is the empty string. +. A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1, + $2, $3, (though those are still set) because the numeric variables get used + for other things in complicated expansions. - . The item @[] matches any of the local host's interface addresses. +. The default for rfc1413_query_timeout has been changed from 30s to 5s. - . Lookups are assumed to be "net-" style lookups, even if "net-" is not - specified. Thus, the following are equivalent: +. It is possible to use setclassresources() on some BSD OS to control the + resources used in pipe deliveries. - ${if match_ip{$sender_host_address}{lsearch;/some/file}... - ${if match_ip{$sender_host_address}{net-lsearch;/some/file}... +. A new ACL modifier called add_header, which can be used with any verb. - You do need to specify the "net-" prefix if you want to specify a - specific address mask, for example, by using "net24-". +. More errors are detectable in retry rules. -PH/06 The "+all" debug selector used to set the flags for all possible output; - it is something that people tend to use semi-automatically when - generating debug output for me or for the list. However, by including - "+memory", an awful lot of output that is very rarely of interest was - generated. I have changed this so that "+all" no longer includes - "+memory". However, "-all" still turns everything off. +There are a number of other additions too. -Version 4.51 +Version 4.60 ------------ -PH/01 The format in which GnuTLS parameters are written to the gnutls-param - file in the spool directory has been changed. This change has been made - to alleviate problems that some people had with the generation of the - parameters by Exim when /dev/random was exhausted. In this situation, - Exim would hang until /dev/random acquired some more entropy. - - The new code exports and imports the DH and RSA parameters in PEM - format. This means that the parameters can be generated externally using - the certtool command that is part of GnuTLS. +The documentation is up-to-date for the 4.60 release. Major new features since +the 4.50 release are: - To replace the parameters with new ones, instead of deleting the file - and letting Exim re-create it, you can generate new parameters using - certtool and, when this has been done, replace Exim's cache file by - renaming. The relevant commands are something like this: +. Support for SQLite. - # rm -f new.params - # touch new.params - # chown exim:exim new.params - # chmod 0400 new.params - # certtool --generate-privkey --bits 512 >new.params - # echo "" >>new.params - # certtool --generate-dh-params --bits 1024 >> new.params - # mv new.params params +. Support for IGNOREQUOTA in LMTP. - If Exim never has to generate the parameters itself, the possibility of - stalling is removed. +. Extensions to the "submission mode" features. -PH/02 A new expansion item for dynamically loading and calling a locally- - written C function is now provided, if Exim is compiled with +. Support for Client SMTP Authorization (CSA). - EXPAND_DLFUNC=yes +. Support for ratelimiting hosts and users. - set in Local/Makefile. The facility is not included by default (a - suitable error is given if you try to use it when it is not there.) +. New expansion items to help with the BATV "prvs" scheme. - If you enable EXPAND_DLFUNC, you should also be aware of the new redirect - router option forbid_filter_dlfunc. If you have unprivileged users on - your system who are permitted to create filter files, you might want to - set forbid_filter_dlfunc=true in the appropriate router, to stop them - using ${dlfunc to run code within Exim. - - You load and call an external function like this: - - ${dlfunc{/some/file}{function}{arg1}{arg2}...} - - Once loaded, Exim remembers the dynamically loaded object so that it - doesn't reload the same object file in the same Exim process (but of - course Exim does start new processes frequently). - - There may be from zero to eight arguments to the function. When compiling - a local function that is to be called in this way, local_scan.h should be - included. The Exim variables and functions that are defined by that API - are also available for dynamically loaded functions. The function itself - must have the following type: - - int dlfunction(uschar **yield, int argc, uschar *argv[]) - - Where "uschar" is a typedef for "unsigned char" in local_scan.h. The - function should return one of the following values: - - OK Success. The string that is placed in "yield" is put into - the expanded string that is being built. - - FAIL A non-forced expansion failure occurs, with the error - message taken from "yield", if it is set. - - FAIL_FORCED A forced expansion failure occurs, with the error message - taken from "yield" if it is set. - - ERROR Same as FAIL, except that a panic log entry is written. - - When compiling a function that is to be used in this way with gcc, - you need to add -shared to the gcc command. Also, in the Exim build-time - configuration, you must add -export-dynamic to EXTRALIBS. - -TF/01 $received_time is a new expansion variable containing the time and date - as a number of seconds since the start of the Unix epoch when the - current message was received. - -PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in - Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API, - in use from radiusclient 0.4.0 onwards, be used. It does not appear to be - possible to detect the different versions automatically. - -PH/04 There is a new option called acl_not_smtp_mime that allows you to scan - MIME parts in non-SMTP messages. It operates in exactly the same way as - acl_smtp_mime - -PH/05 It is now possible to redefine a macro within the configuration file. - The macro must have been previously defined within the configuration (or - an included file). A definition on the command line using the -D option - causes all definitions and redefinitions within the file to be ignored. - In other words, -D overrides any values that are set in the file. - Redefinition is specified by using '==' instead of '='. For example: - - MAC1 = initial value - ... - MAC1 == updated value - - Redefinition does not alter the order in which the macros are applied to - the subsequent lines of the configuration file. It is still the same - order in which the macros were originally defined. All that changes is - the macro's value. Redefinition makes it possible to accumulate values. - For example: - - MAC1 = initial value - ... - MAC1 == MAC1 and something added - - This can be helpful in situations where the configuration file is built - from a number of other files. - -PH/06 Macros may now be defined or redefined between router, transport, - authenticator, or ACL definitions, as well as in the main part of the - configuration. They may not, however, be changed within an individual - driver or ACL, or in the local_scan, retry, or rewrite sections of the - configuration. - -PH/07 $acl_verify_message is now set immediately after the failure of a - verification in an ACL, and so is available in subsequent modifiers. In - particular, the message can be preserved by coding like this: - - warn !verify = sender - set acl_m0 = $acl_verify_message - - Previously, $acl_verify_message was set only while expanding "message" - and "log_message" when a very denied access. - -PH/08 The redirect router has two new options, sieve_useraddress and - sieve_subaddress. These are passed to a Sieve filter to specify the :user - and :subaddress parts of an address. Both options are unset by default. - However, when a Sieve filter is run, if sieve_useraddress is unset, the - entire original local part (including any prefix or suffix) is used for - :user. An unset subaddress is treated as an empty subaddress. - -PH/09 Quota values can be followed by G as well as K and M. - -PH/10 $message_linecount is a new variable that contains the total number of - lines in the header and body of the message. Compare $body_linecount, - which is the count for the body only. During the DATA and - content-scanning ACLs, $message_linecount contains the number of lines - received. Before delivery happens (that is, before filters, routers, and - transports run) the count is increased to include the Received: header - line that Exim standardly adds, and also any other header lines that are - added by ACLs. The blank line that separates the message header from the - body is not counted. Here is an example of the use of this variable in a - DATA ACL: - - deny message = Too many lines in message header - condition = \ - ${if <{250}{${eval: $message_linecount - $body_linecount}}} - - In the MAIL and RCPT ACLs, the value is zero because at that stage the - message has not yet been received. - -PH/11 In a ${run expansion, the variable $value (which contains the standard - output) is now also usable in the "else" string. - -PH/12 In a pipe transport, although a timeout while waiting for the pipe - process to complete was treated as a delivery failure, a timeout while - writing the message to the pipe was logged, but erroneously treated as a - successful delivery. Such timeouts include transport filter timeouts. For - consistency with the overall process timeout, these timeouts are now - treated as errors, giving rise to delivery failures by default. However, - there is now a new Boolean option for the pipe transport called - timeout_defer, which, if set TRUE, converts the failures into defers for - both kinds of timeout. A transport filter timeout is now identified in - the log output. - - -Version 4.50 ------------- +. A "match_ip" condition, that matches an IP address against a list. -The documentation is up-to-date for the 4.50 release. +There are many more minor changes. ****