/[smeserver]/rpms/qmail/sme9/moreipme.README
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Annotation of /rpms/qmail/sme9/moreipme.README

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Revision 1.1 - (hide annotations) (download)
Thu Apr 13 16:06:04 2017 UTC (7 years, 6 months ago) by unnilennium
Branch: MAIN
CVS Tags: qmail-1_03-23_el6_sme, qmail-1_03-20_el6_sme, qmail-1_03-22_el6_sme, qmail-1_03-24_el6_sme, qmail-1_03-21_el6_sme, HEAD
* Thu Apr 13 2017 Jean-Philipe Pialasse <tests@pialasse.com> 1.03-20.sme
- added documentation [SME: 9704]
- added binaries ipmetest et ipmeprint to help configuration

1 unnilennium 1.1 ###########
2     ### WHO ###
3     ###########
4    
5     This patch was written by Scott Gifford <sgifford@suspectclass.com>.
6     The design and much of the code for supporting "notipme" was
7     contributed by Charles Cazabon <charlesc@discworld.dyndns.org>.
8    
9    
10     ############
11     ### WHAT ###
12     ############
13    
14     This patch may be necessary in some configurations that involve network
15     address translation or port forwarding. It prevents a problem caused
16     by an MX or other mail routing directive instructing qmail to connect to
17     itself without realizing it's connecting to itself. When this happens,
18     it accepts the message, finds out where to deliver it to (itself), and
19     promptly reconnects to itself to deliver the message. Eventually, when
20     it has done this 20 or 30 times, it will give up and bounce the message,
21     but not before sucking up all of your CPU while it's happening.
22    
23     It may also be useful in some configurations that have multiple qmail
24     servers configured on different interfaces of the same system. qmail
25     will normally refuse to deliver mail by SMTP to the machine it's
26     running on, but with multiple copies of qmail, you may want to prevent
27     this behavior.
28    
29     Normally, qmail can detect what IP addresses refer to itself by getting
30     a list of all network interfaces with IP addresses from the operating
31     system. It uses this list to determine whether connecting to an address
32     will cause it to connect to itself, and avoid the situation (it calls
33     the perm_ambigmx() function, which prints the message:
34    
35     Sorry. Although I'm listed as a best-preference MX or A for that host,
36     it isn't in my control/locals file, so I don't treat it as local. (#5.4.6)
37    
38     But in situations where the OS is not aware of all IP addresses that
39     connect back to itself, this detection fails, causing the CPU-sucking
40     phenomenon described above. This can happen if there is a network
41     address translation device in front of the qmail server, such as a
42     load-balancer or a router which allows you to share one IP address among
43     several machines; if there is a port forwarder forwarding connections
44     from some other machine to the SMTP server on the qmail server; or in
45     configurations where a "dumb" mailserver is configured to use your qmail
46     server as a "smarthost", delivering all mail to it without inspection.
47    
48     To solve this, other IP addresses which will ultimately connect back to
49     your machine can be added to the file "control/moreipme", one per line.
50     qmail will treat all addresses in this file exactly as if they were
51     local, and if it finds an MX record or other mail routing information
52     which would cause it to connect to any of these addresses, it will call
53     perm_ambigmx(), and print the above error message.
54    
55     Additionally, IP addresses which the system detects but which should
56     *not* be treated as local can be removed from qmail's ipme list by
57     adding them to the file "control/notipme".
58    
59     IP addresses can be specified as individual addresses in the usual
60     dotted-quad format, or as entire networks using a slash followed by
61     the full dotted-quad netmask:
62    
63     127.0.0.1
64     127.0.0.1/255.255.255.255
65     127.0.0.0/255.0.0.0
66     10.0.0.0/255.255.255.0
67    
68     An individual address is treated exactly like a network with a mask of
69     255.255.255.255. Addresses of interfaces found on the system are
70     added with their individual addresses. In addition, these addresses
71     are implicitly added:
72    
73     0.0.0.0
74     127.0.0.0/255.0.0.0
75    
76     So the list of system addresses (the "ipme" list) is, in order,
77     127.0.0.0/255.0.0.0, 0.0.0.0, then all actual interfaces on the system
78     in the order they are reported, then the contents of the "moreipme"
79     file. The list of excluded addresses (the "notipme" list) is just the
80     contents of the "notipme" file.
81    
82     If an address appears in both the ipme list and the notipme list, the
83     entry with the longest netmask wins. If the netmask lengths are the
84     same, notipme wins.
85    
86     For example, if the ipme list has 127.0.0.0/255.0.0.0 and notipme has
87     127.0.0.2, then 127.0.0.2 will not be considered me because the entry
88     in notipme has a 32-bit mask. If the notipme list has
89     127.0.0.0/255.0.0.0, all of 127.* will not be considered me.
90    
91     You can run the program "ipmeprint" from the source directory to see
92     what interfaces qmail is detecting or finds in moreipme.
93    
94     You can run the program "ipmetest" from the source directory to test
95     your configuration. It takes as its first and only parameter an IP
96     address to test, and prints either "me" or "not me".
97    
98     ###########
99     ### HOW ###
100     ###########
101    
102     To apply the patch, download and save it somewhere, then cd into your
103     qmail source directory.
104    
105     For stock qmail, download qmail-1.03-moreipme-0.6.patch then run:
106    
107     cd qmail-1.03
108     patch -p1 </path/to/qmail-1.03-moreipme-0.6.patch
109    
110     For netqmail, first download netqmail-1.05, and run the included
111     collate.sh script. Then download netqmail-1.05-moreipme-0.6.patch and
112     apply it to the netqmail base directory, after runn:
113    
114     cd netqmail-1.05
115     patch -p1 </path/to/netqmail-1.05-moreipme-0.6.patch
116    
117    
118     ###################
119     ### OTHER NOTES ###
120     ###################
121    
122     This patch also incorporates the "0.0.0.0" patch, which causes qmail
123     to recognize the IP address 0.0.0.0 as a local address. See:
124    
125     http://www.suspectclass.com/~sgifford/qmail/qmail-0.0.0.0.README
126    
127     for more information, and
128    
129     http://www.suspectclass.com/~sgifford/qmail/qmail-0.0.0.0.patch
130    
131     for a copy of the patch.
132    
133    
134     ###############
135     ### HISTORY ###
136     ###############
137    
138     2004 May 22 - Patch version 0.6 released. Fix from Richard Dawe where
139     masks weren't handled properly, removed some dead code,
140     updated comments and docs. Produce a copy of the patch
141     for netqmail-1.05.
142    
143     2003 Apr 29 - Patch version 0.5 released. Added support for netmasks
144     in moreipme and notipme, ipmetest utility, 127/8 as
145     implicit ipme.
146    
147     2002 Apr 26 - Patch version 0.4 released. Includes support for "notipme" file.
148     Many other small fixes and cleanups. Fixes ipmeprint to
149     chdir(/var/qmail) before running.
150    
151     2001 Oct 8 - Original release of patch.
152    
153     2001 Jan 22 - (roughly) Original release of 0.0.0.0 patch.
154    

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