Doc: Add hint about spamd and half-closed connections

[users/jgh/exim.git] / doc / doc-src / FAQ.src

diff --git a/doc/doc-src/FAQ.src b/doc/doc-src/FAQ.src
index a90f03586a14f9c464d82f7a00302c642f64b423..9280e0314e9ba85d43c109b279523fa77a998d74 100644 (file)
--- a/doc/doc-src/FAQ.src
+++ b/doc/doc-src/FAQ.src
@@ -1,4 +1,3 @@
-## $Cambridge: exim/doc/doc-src/FAQ.src,v 1.4 2004/11/12 14:42:04 nm4 Exp $

 ##
 ## This file is processed by Perl scripts to produce an ASCII and an HTML
 ## version. Lines starting with ## are omitted. The markup used with paragraphs
 ##
 ## This file is processed by Perl scripts to produce an ASCII and an HTML
 ## version. Lines starting with ## are omitted. The markup used with paragraphs


@@ -371,11 +370,11 @@ A0017: \*Broken pipe*\ is the error you get on some OS when the remote host just
 
        You can test the link using pings of large packets and see what works:
 
 
        You can test the link using pings of large packets and see what works:
 

-==>     ping -s host 2048
+==>      ping -s host 2048

 
        Try reducing the MTU on the sending host:
 
 
        Try reducing the MTU on the sending host:
 

-==>     ifconfig le0 mtu 1300
+==>      ifconfig le0 mtu 1300

 
        Alternatively, you can reduce the size of the buffer Exim uses for SMTP
        output by putting something like
 
        Alternatively, you can reduce the size of the buffer Exim uses for SMTP
        output by putting something like


@@ -467,7 +466,7 @@ A0020: These kinds of delay are usually caused by some kind of network problem
 ==>          deny  hosts = *.x.example
 
            If at all possible, you should use IP addresses instead of host
 ==>          deny  hosts = *.x.example
 
            If at all possible, you should use IP addresses instead of host

-           names in blocking lists in order to to avoid this problem.
+           names in blocking lists in order to avoid this problem.

 
        You can use the \-bh-\ option to get more information about what is
        happening at the start of a connection. However, note that the \-bh-\
 
        You can use the \-bh-\ option to get more information about what is
        happening at the start of a connection. However, note that the \-bh-\


@@ -743,7 +742,7 @@ A0036: Your configuration specifies that local mailboxes are all held in
            second solution is used, users can empty their mailboxes by updating
            them, but cannot delete them.
 
            second solution is used, users can empty their mailboxes by updating
            them, but cannot delete them.
 

-       If your problem involves mail to \/root/\, see also Q0507.
+       If your problem involves mail to \/root/\, see also Q0039.

 
 
 Q0037: I am experiencing mailbox locking problems with Sun's \"mailtool"\ used
 
 
 Q0037: I am experiencing mailbox locking problems with Sun's \"mailtool"\ used


@@ -851,7 +850,9 @@ A0044: Exim has been unable to create a file in its spool area in which to
 
        If you are running Exim with an alternate configuration file using a
        command such as \"exim -C altconfig..."\, remember that the use of -C
 
        If you are running Exim with an alternate configuration file using a
        command such as \"exim -C altconfig..."\, remember that the use of -C

-       takes away Exim's root privilege.
+       takes away Exim's root privilege, unless \\TRUSTED_CONFIG_LIST\\
+       is set in \(Local/Makefile)\ and the corresponding file contains a
+       prefix which matches the alternative configuration file being used.

 
        Check that you have defined the spool directory correctly by running
 
 
        Check that you have defined the spool directory correctly by running
 


@@ -1147,25 +1148,17 @@ Q0065: When (as \/root/\) I use -C to run Exim with an alternate configuration
        trying to run an \%autoreply%\ transport. Why is this?
 
 A0065: When Exim is called with -C, it passes on -C to any instances of itself
        trying to run an \%autoreply%\ transport. Why is this?
 
 A0065: When Exim is called with -C, it passes on -C to any instances of itself

-       that it calls (so that the whole sequence uses the same config file). If
-       it's running as \/exim/\ when it does this, all is well. However, if it
-       happens as a consequence of a non-privileged user running \%autoreply%\,
-       the called Exim gives up its root privilege. Then it can't write to the
-       spool.
-
-       This means that you can't use -C (even as \/root/\) to run an instance of
-       Exim that is going to try to run \%autoreply%\ from a process that is
-       neither \/root/\ nor \/exim/\. Because of the architecture of Exim (using
-       re-execs to regain privilege), there isn't any way round this
-       restriction. Therefore, the only way you can make this scenario work is
-       to run the \%autoreply%\ transport as \/exim/\ (that is, the user that
-       owns the Exim spool files). This may be satisfactory for autoreplies
-       that are essentially system-generated, but of course is no good for
-       autoreplies from unprivileged users, where you want the \%autoreply%\
-       transport to be run as the user. To get that to work with an alternate
-       configuration, you'll have to use two Exim binaries, with different
-       configuration file names in each. See S001 for a script that patches
-       the configuration name in an Exim binary.
+       that it calls (so that the whole sequence uses the same config file).
+       However, Exim gives up its root privilege if any user except \/root\/
+       passes a -C option to use a non-default configuration file, and that
+       includes the case where Exim re-execs itself to regain root privilege.
+       Thus it can't write to the spool.
+
+       The fix for this is to use the \\TRUSTED_CONFIG_LIST\\ build-time
+       option. This defines a file containing a list of 'trusted' prefixes for
+       configuration files. Any configuration file specified with -C, if it
+       matches a prefix listed in that file, will be used without dropping root
+       privileges (as long as it is not writeable by a non-root user).

 
 
 Q0066: What does the message \*unable to set gid=xxx or uid=xxx*\ mean?
 
 
 Q0066: What does the message \*unable to set gid=xxx or uid=xxx*\ mean?


@@ -1322,7 +1315,7 @@ A0076: You are probably putting your reject items into the main log as well;
        by a \"mail.info"\ descriptor).
        Test this by running the command:
 
        by a \"mail.info"\ descriptor).
        Test this by running the command:
 

-==>     logger -p mail.notice test
+==>      logger -p mail.notice test

 
        and seeing which logs it goes into. From Exim release 4.31 it is
        possible to disable the rejectlog by setting \write_rejectlog\ false.
 
        and seeing which logs it goes into. From Exim release 4.31 it is
        possible to disable the rejectlog by setting \write_rejectlog\ false.


@@ -1811,9 +1804,9 @@ A0115: You are using FreeBSD, or another OS that has a \^make^\ command which
        ensure that this happens throughout the build, it's best to export it in
        your environment:
 
        ensure that this happens throughout the build, it's best to export it in
        your environment:
 

-==>     MAKEFLAGS='-B'
-        export MAKEFLAGS
-        make
+==>      MAKEFLAGS='-B'
+         export MAKEFLAGS
+          make

 
 
 Q0116: I have tried to build Exim with Berkeley DB 3 and 4, but I always get
 
 
 Q0116: I have tried to build Exim with Berkeley DB 3 and 4, but I always get


@@ -2323,7 +2316,7 @@ A0310: If a DNS lookup returns no MXs, Exim looks for an address record, in
 
 
 Q0311: When a DNS lookup for MX records fails to complete, why doesn't Exim
 
 
 Q0311: When a DNS lookup for MX records fails to complete, why doesn't Exim

-       send the messsage to the host defined by the A record?
+       send the message to the host defined by the A record?

 
 A0311: The RFCs are quite clear on this. Only if it is known that there are no
        MX records is an MTA allowed to make use of the A record. When an MX
 
 A0311: The RFCs are quite clear on this. Only if it is known that there are no
        MX records is an MTA allowed to make use of the A record. When an MX


@@ -2478,25 +2471,25 @@ A0319: The admin in question is an idiot. Exim will always freeze such messages
 ==>      # Don't allow domains whose single MX (or A) record is a
          # "special-use IPv4 address", as listed in RFC 3330.
          ignore_target_hosts = \
 ==>      # Don't allow domains whose single MX (or A) record is a
          # "special-use IPv4 address", as listed in RFC 3330.
          ignore_target_hosts = \

-              # Hosts on "this network"; RFC 1700 (page 4) states that these
-              # are only allowed as source addresses
-              0.0.0.0/8 : \
-              # Private networks, RFC 1918
-              10.0.0.0/8 : 172.16.0.0/12 : 192.168.0.0/16 : \
-              # Internet host loopback address, RFC 1700 (page 5)
-              127.0.0.0/8 : \
-              # "Link local" block
-              169.254.0.0/16 : \
-              # "TEST-NET" - should not appear on the public Internet
-              192.0.2.0/24 : \
-              # 6to4 relay anycast addresses, RFC 3068
-              192.88.99.0/24 : \
-              # Network interconnect device benchmark testing, RFC 2544
-              198.18.0.0/15 : \
-              # Multicast addresses, RFC 3171
-              224.0.0.0/4 : \
-              # Reserved for future use, RFC 1700 (page 4)
-              240.0.0.0/4
+         # Hosts on "this network"; RFC 1700 (page 4) states that these
+         # are only allowed as source addresses
+         0.0.0.0/8 : \
+         # Private networks, RFC 1918
+         10.0.0.0/8 : 172.16.0.0/12 : 192.168.0.0/16 : \
+         # Internet host loopback address, RFC 1700 (page 5)
+         127.0.0.0/8 : \
+         # "Link local" block
+         169.254.0.0/16 : \
+         # "TEST-NET" - should not appear on the public Internet
+         192.0.2.0/24 : \
+         # 6to4 relay anycast addresses, RFC 3068
+         192.88.99.0/24 : \
+         # Network interconnect device benchmark testing, RFC 2544
+         198.18.0.0/15 : \
+         # Multicast addresses, RFC 3171
+         224.0.0.0/4 : \
+         # Reserved for future use, RFC 1700 (page 4)
+         240.0.0.0/4

 
 
 Q0320: How can I arrange for all mail to \*user@some.domain*\ to be forwarded
 
 
 Q0320: How can I arrange for all mail to \*user@some.domain*\ to be forwarded


@@ -2684,7 +2677,7 @@ A0408: Set the \qualify_preserve_domain\ option on the \%redirect%\ router.
 Q0409: I want mail for any local part at certain virtual domains to go
        to a single address for each domain.
 
 Q0409: I want mail for any local part at certain virtual domains to go
        to a single address for each domain.
 

-A0409: One way to to this is
+A0409: One way to do this is

 
 ==>      virtual:
            driver = redirect
 
 ==>      virtual:
            driver = redirect


@@ -2756,7 +2749,7 @@ A0413: Setting \skip_syntax_errors\ on the redirect router causes syntax
            driver = accept
            check_local_user
            transport = local_delivery
            driver = accept
            check_local_user
            transport = local_delivery

-           prefix = real-
+           local_part_prefix = real-

 
        before the \%redirect%\ router that handles \(.forward)\ files. This will
        do an ordinary local delivery without \(.forward)\ processing, if the
 
        before the \%redirect%\ router that handles \(.forward)\ files. This will
        do an ordinary local delivery without \(.forward)\ processing, if the


@@ -3672,10 +3665,10 @@ A0606: You need to unset the \mesage_prefix\ option, or change it so that its
        transport could be:
 
 ==>      local_delivery_mbx:
        transport could be:
 
 ==>      local_delivery_mbx:

-          driver = pipe
-          command = /usr/local/bin/tmail $local_part
-          user = exim
-          current_directory = /
+           driver = pipe
+           command = /usr/local/bin/tmail $local_part
+           user = exim
+           current_directory = /

            use_crlf
            message_prefix =
 
            use_crlf
            message_prefix =
 


@@ -4403,7 +4396,7 @@ A0710: Set up a file (or database) containing the messages, keyed by the
 ==>      deny message   = ${lookup{$sender_address=>$local_part@$domain}\
                           lsearch{/that/file}}
               condition = ${lookup{$sender_address=>$local_part@$domain}\
 ==>      deny message   = ${lookup{$sender_address=>$local_part@$domain}\
                           lsearch{/that/file}}
               condition = ${lookup{$sender_address=>$local_part@$domain}\

-                          lsearch{/that/file}}{yes}{no}}
+                          lsearch{/that/file}{yes}{no}}

 
        The condition is tested first. If the lookup succeeds, the condition
        succeeds so access is denied. The message is then expanded, but the
 
        The condition is tested first. If the lookup succeeds, the condition
        succeeds so access is denied. The message is then expanded, but the


@@ -4807,10 +4800,10 @@ A0735: Many workstation clients send single-component names; take care that you
        do not block legitimate mail. With that proviso, you can do it using
        something like this in an ACL:
 
        do not block legitimate mail. With that proviso, you can do it using
        something like this in an ACL:
 

-==>     drop  message = HELO doesn't look like a hostname
-              log_message = Not a hostname
-              condition = ${if match{$sender_helo_name} \
-                               {\N^[^.].*\.[^.]+$\N}{no}{yes}}
+==>      drop  message = HELO doesn't look like a hostname
+               log_message = Not a hostname
+               condition = ${if match{$sender_helo_name} \
+                           {\N^[^.].*\.[^.]+$\N}{no}{yes}}

 
        This means: Drop the HELO unless it contains a dot somewhere in the HELO
        string, but the string may not begin or end with a dot. Thus, the
 
        This means: Drop the HELO unless it contains a dot somewhere in the HELO
        string, but the string may not begin or end with a dot. Thus, the


@@ -5003,8 +4996,8 @@ Q0804: I'm using this rewriting rule to change login names into ``friendly''
        names, but if mail comes in for an upper case login name, it doesn't
        get rewritten.
 
        names, but if mail comes in for an upper case login name, it doesn't
        get rewritten.
 

-==>     *@my.domain     ${lookup{$1}dbm{/usr/lib/exim/longforms}\
-                        {$value}fail}@my.domain bcfrtFT
+==>      *@my.domain   ${lookup{$1}dbm{/usr/lib/exim/longforms}\
+                        {$value}fail}@my.domain bcfrtFT

 
        The longforms database has entries of the form:
 
 
        The longforms database has entries of the form:
 


@@ -5020,11 +5013,11 @@ A0805: It depends on what you mean by ``fail a message'' and what addresses you
        are rewriting. If you are rewriting recipient addresses for your local
        domain, you can do:
 
        are rewriting. If you are rewriting recipient addresses for your local
        domain, you can do:
 

-==>     *@dom.ain  ${lookup{$1}dbm{/wher/ever}{$value}{failaddr}}  Ehq
+==>      *@dom.ain  ${lookup{$1}dbm{/wher/ever}{$value}{failaddr}}  Ehq

 
        and in your alias file put something like
 
 
        and in your alias file put something like
 

-==>     failaddr:   :fail: Rewriting failed
+==>      failaddr:   :fail: Rewriting failed

 
        This fails a single recipient - others are processed independently.
 
 
        This fails a single recipient - others are processed independently.
 


@@ -5773,8 +5766,8 @@ A1701: It seems that some clients require that the certificate presented by
            encrypt the user/site/leaf certificate. If this isn't acceptable,
            you seem to be able to strip out the passphrase as follows:
 
            encrypt the user/site/leaf certificate. If this isn't acceptable,
            you seem to be able to strip out the passphrase as follows:
 

-==>         openssl rsa -in user.key -our user.key.new
-            mv user.key.new
+==>          openssl rsa -in user.key -our user.key.new
+             mv user.key.new

 
            This should be done immediately after \(user.key)\ is created.
 
 
            This should be done immediately after \(user.key)\ is created.
 


@@ -6625,13 +6618,13 @@ A9604: The problem appears to be the number of open files the system can
 ==>      # Now System is up, Modify kernel parameters for max open etc.
 
 ==>      if [ -f /proc/sys/kernel/file-max ]; then
 ==>      # Now System is up, Modify kernel parameters for max open etc.
 
 ==>      if [ -f /proc/sys/kernel/file-max ]; then

-                echo 16384 >> /proc/sys/kernel/file-max
+           echo 16384 >> /proc/sys/kernel/file-max

          fi
          if [ -f /proc/sys/kernel/inode-max ]; then
          fi
          if [ -f /proc/sys/kernel/inode-max ]; then

-                echo 24576 >> /proc/sys/kernel/inode-max
+           echo 24576 >> /proc/sys/kernel/inode-max

          fi
          if [ -f /proc/sys/kernel/file-nr ]; then
          fi
          if [ -f /proc/sys/kernel/file-nr ]; then

-                echo 2160 >> /proc/sys/kernel/file-nr
+           echo 2160 >> /proc/sys/kernel/file-nr

          fi
 
        By echoing the value you want for file-max to the file \(file-max)\ etc.,
          fi
 
        By echoing the value you want for file-max to the file \(file-max)\ etc.,