INDEX
1. I'm using an older version of MaraDNS
2. How do I try out MaraDNS?
3. What license is MaraDNS released under?
4. How do I report bugs in MaraDNS?
5. Some of the postings to the mailing list do not talk about MaraDNS!
6. How do I get off the mailing list?
7. How do I set up reverse DNS on MaraDNS?
8. I am on a slow network, and MaraDNS can not process recursive queries
9. When I try to run MaraDNS, I get a cryptic error message.
10. After I start MaraDNS, I can not see the process when I run netstat -na
11. What string library does MaraDNS use?
12. Why does MaraDNS use a multi-threaded model?
13. I feel that XXX feature should be added to MaraDNS
14. I feel that MaraDNS should use another documentation format
15. Is there any process I need to follow to add a patch to MaraDNS?
16. Can MaraDNS act as a primary nameserver?
17. Can MaraDNS act as a secondary nameserver?
18. What is the difference between an authoritative and a recursive DNS server?
19. The getzone client isn't allowing me to add certain hostnames to my zone
20. Is MaraDNS portable?
21. Can I use MaraDNS in Windows?
22. MaraDNS freezes up after being used for a while
23. What kind of Python integration does MaraDNS have
24. Doesn't "kvar" mean "four" in Esperanto?
25. How scalable is MaraDNS?
26. I am having problems setting upstream_servers
27. Why doesn't the MaraDNS.org web page validate?
28. How do MX records work?
29. Does MaraDNS have support for SPF?
30. I'm having problems resolving CNAMES I have set up.
31. I have a NS delegation, and MaraDNS is doing strange things.
32. I am transferring a zone from another server, but the NS records are these strange "synth-ip"
records.
33. Where is the root.hints file?
34. Are there any plans to use autoconf to build MaraDNS?
35. How do I change the compiler or compile-time flags with MaraDNS' build process?
36. Will you make a package for the particular Linux distribution I am using?
37. I am using the native Windows port of MaraDNS, and some features are not working.
38. MaraDNS isn't starting up
39. You make a lot of releases of MaraDNS; at our ISP/IT department, updating software is non-
trivial.
40. I have star records in my zones, and am having problems with NXDOMAINs/IPV6 resolution
41. I have a zone with only SOA/NS records, and the zone is not working.
42. I am having problems registering my domain with AFNIC (the registrar for .fr domains)
43. I can't see the full answers for subdomains I have delegated
44. MaraDNS 1 has a problem resolving a domain
45. MaraDNS 1.2 has issues with NXDOMAINS and case sensitivity.
46. Can MaraDNS offer protection from phishing and malicious sites?
47. Does maradns support star (wildcard) records?
48. I'm having problems using MaraDNS with some *NIX command line applications like telnet
49. My virus scanner reports that MaraDNS or Deadwood has a virus
50. I can not subscribe to the MaraDNS mailing list
51. How does MaraDNS respond to EDNS (RFC2671) packets?
52. How to I get MaraDNS to always give the same IP to all DNS queries?
53. Why did you change MaraDNS' tagline?
54. How do you stop MaraDNS from taking part in a distributed denial-of-service attack?
55. What about DNS-over-TCP?
56. How do I use MaraDNS with systemd?
57. Why doesn't MaraDNS use IP_FREEBIND?
58. Is there a web interface for MaraDNS?
59. What does the message “don’t forget the trailing dot” mean?
60. Does MaraDNS support newer top level domains?
ANSWERS1.I'musinganolderversionofMaraDNS
Upgrade to MaraDNS 2.0. Here is an upgrade guide.
MaraDNS 1.4 is only supported for critical security updates; this support is being phased out and MaraDNS
1 will no longer be supported on June 21, 2015.
2.HowdoItryoutMaraDNS?
Read the quick start guide, which is the file named 0QuickStart in the MaraDNS distribution.
3.WhatlicenseisMaraDNSreleasedunder?
MaraDNS is released with the following two-clause BSD-type license:
Copyright (c) 2002-2015 Sam Trenholme and others
TERMS
Redistribution and use in source and binary forms, with or without modification, are permitted
provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and
the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions
and the following disclaimer in the documentation and/or other materials provided with the
distribution.
This software is provided 'as is' with no guarantees of correctness or fitness for purpose.
4.HowdoIreportbugsinMaraDNS?
Post your bug report as a Github issue.
5.SomeofthepostingstothemailinglistdonottalkaboutMaraDNS!
As of September 2013, the mailing list has become moderated and only postings on the mailing list are
relevant MaraDNS announcements.
6.HowdoIgetoffthemailinglist?
Send an email to list-unsubscribe@maradns.org, or an email to list-request@maradns.org with "unsubscribe"
as the subject line.
The mailing list will send you an email confirming the unsubscribe request; this email needs to be
replied to in order to get off the list.
7.HowdoIsetupreverseDNSonMaraDNS?
Reverse DNS (sometimes called "reverse mapping") is set up by using PTR (pointer) records. For example,
the PTR record which performs the reverse DNS lookup for the ip 10.2.3.4 looks like this in a CSV2 zone
file:
4.3.2.10.in-addr.arpa. PTR www.example.com.
It is also possible to use a special "FQDN4" which automatically sets up the reverse mapping of a given
record:
www.example.com. FQDN4 10.2.3.4
If you wish to have a PTR (reverse DNS lookup; getting a DNS name from a numeric IP) record work on the
internet at large, it is not a simple matter of just adding a record like this to a MaraDNS zonefile. One
also needs control of the appropriate in-addr.arpa. domain.
While it could make logical sense to contact the IP 10.11.12.13 when trying to get the reverse DNS lookup
(fully qualified domain name) for a given IP, DNS servers don't do this. DNS server, instead, contact the
root DNS servers for a given in-addr.arpa name to get the reverse DNS lookup, just like they do with any
other record type.
When an internet service provider is given a block of IPs, they are also given control of the DNS zones
which allow them to control reverse DNS lookups for those IPs. While it is possible to obtain a domain
and run a DNS server without the knowledge or intervention of an ISP, being able to control reverse DNS
lookups for those IPs requires ISP intervention.
8.Iamonaslownetwork,andDeadwoodcannotprocessrecursivequeries
Deadwood, by default, only waits two seconds for a reply from a remote DNS server. This default can be
increased by adding a line like this in the mararc file:
timeout_seconds = 5
Note that making this too high will slow MaraDNS down when DNS servers are down, which is, alas, all too
common on today's internet.
9.WhenItrytorunMaraDNS,Igetacrypticerrormessage.
There is usually some context of where there is a syntax error in a data file before the cryptic error
message. For example, when there is a syntax error in a csv2 zone file, MaraDNS will tell you exactly at
what point it had to terminate parsing of the zone file.
If MaraDNS does return a cryptic error message without letting you know what is wrong, let us know in a
Github issue so that we can fix the bug. MaraDNS is designed to be easy to use; cryptic error messages go
against this spirit.
10.AfterIstartMaraDNS,IcannotseetheprocesswhenIrunnetstat-na
Udp services do not have a prominent "LISTEN" when netstat is run.
When MaraDNS is up, the relevant line in the netstat output looks like this: udp 0 0 127.0.0.1:53
0.0.0.0:*
While on the topic of netstat, if you run netstat -nap as root on Linux and some other *nix operating
systems, you can see the names of the processes which are providing internet services.
11.WhatstringlibrarydoesMaraDNSuse?
MaraDNS uses its own string library, which is called the "js_string" library. Man pages for most of the
functions in the js_string library are in the folder doc/man of the MaraDNS distribution
12.WhydoesMaraDNSuseamulti-threadedmodel?
MaraDNS 2.0 no longer uses threads.
It took me three years to rewrite MaraDNS' recursive resolver as a separate non-threaded daemon. This has
been done, and now all recursion is done with Deadwood which does not need threads.
13.IfeelthatXXXfeatureshouldbeaddedtoMaraDNS
There are no plans to add new features to MaraDNS or Deadwood at this time.
14.IfeelthatMaraDNSshoulduseanotherdocumentationformat
The reason that MaraDNS uses its own documentation format is to satisfy both the needs of translators to
have a unified document format and my own need to use a documentation format that is simple enough to be
readily understood and which I can add features on an as needed basis.
The documentation format is essentially simplified HTML with some special tags added to meet MaraDNS'
special needs.
This gives me more flexibility to adapt the documentation format to changing needs. For example, when
someone pointed out that it's not a good idea to have man pages with hi-bit characters, it was a simple
matter to add a new HIBIT tag which allows man pages to be without hi-bit characters, and other document
formats to retain hi-bit characters.
Having a given program have its own documentation format is not without precedent; Perl uses its own
"pod" documentation format.
15.IsthereanyprocessIneedtofollowtoaddapatchtoMaraDNS?
I no longer accept third party patches
16.CanMaraDNSactasaprimarynameserver?
Yes.
The zoneserver program serves zones so that other DNS servers can be secondaries for zones which MaraDNS
serves. This is a separate program from the maradns server, which processes authoritative UDP DNS
queries, and Deadwood which processes recursive DNS queries.
See the DNS master document in the MaraDNS tutorial for details.
17.CanMaraDNSactasasecondarynameserver?
Yes.
Please read the DNS slave document, which is part of the MaraDNS tutorial.
18.WhatisthedifferencebetweenanauthoritativeandarecursiveDNSserver?
A recursive DNS server is a DNS server that is able to contact other DNS servers in order to resolve a
given domain name label. This is the kind of DNS server one points to in /etc/resolv.conf. MaraDNS uses
the Deadwood daemon to process recursive DNS queries.
An authoritative DNS server is a DNS server that a recursive server contacts in order to find out the
answer to a given DNS query. The maradns daemon processes authoritative DNS queries.
19.Thefetchzoneclientisn'tallowingmetoaddcertainhostnamestomyzone
For security reasons, MaraDNS' fetchzone client does not add records which are not part of the zone in
question. For example, if someone has a zone for example.com, and this record in the zone:
1.1.1.10.in-addr.arpa. PTR dns.example.com.
MaraDNS will not add the record, since the record is out-of-bailiwick. In other words, it is a host name
that does not end in .example.com.
There are two workarounds for this issue:
* Create a zone file for 1.1.10.in-addr.arpa., and put the PTR records there.
* Use rcp, rsync, or another method to copy over the zone files in question.
20.IsMaraDNSportable?
MaraDNS is developed in CentOS 6 and Windows 7. MaraDNS may or may not compile and run on other systems.
21.CanIuseMaraDNSinWindows?
Yes. There is both a partial mingw32 (native win32 binary) port and a full Cygwin port of MaraDNS; both
of these ports are part of the native build of MaraDNS. Deadwood has full Windows support, including the
ability to run as a service.
22.MaraDNSfreezesupafterbeingusedforawhile
If using your ISP's name servers or some other name servers which are not, in fact, root name servers,
please make sure that you are using the upstream_servers dictionary variable instead of the root_servers
dictionary variable.
If you still see MaraDNS freeze up after making this correction, please send a bug report as a Github
issue.
23.WhatkindofPythonintegrationdoesMaraDNShave
The mararc file uses the same syntax that Python uses; in fact, Python can parse a properly formatted
mararc file.
There is no other integration with Python.
24.Doesn't"kvar"mean"four"inEsperanto?
Indeed, it does. However the use of "kvar" in the MaraDNS source code only coincidentally is an Esperanto
word. "kvar" is short for "Kiwi variable"; a lot of the parsing code comes from the code used in the Kiwi
spam filter project.
25.HowscalableisMaraDNS?
MaraDNS is optimized for serving a small number of domains as quickly as possible. That said, MaraDNS is
remarkably efficnent for serving a large number of domains, as long as the server MaraDNS is on has the
memory to fit all of the domains, and as long as the startup time for loading a large number of domains
can be worked around.
The "big-O" or "theta" growth rates for various MaraDNS functions are as follows, where N is the number
of authoritative host names being served:
Startup time N
Memory usage N
Processing incoming DNS requests 1
As can be seen, MaraDNS will process 1 or 100000 domains in the same amount of time, once the domain
names are loaded in to memory.
26.Iamhavingproblemssettingupstream_servers
upstream_servers is only supported by Deadwood, and is no longer supported in MaraDNS 2.0. The
upstream_servers dwood3rc variable is set thusly:
upstream_servers["."] = "10.3.28.79, 10.2.19.83"
Note the ["."].
Note that the upstream_servers variable needs to be initialized before being used via upstream_servers =
{} (the reason for this is so that a dwood3rc file has 100% Python-compatible syntax). A complete
dwood3rc file that uses upstream_servers may look like this:
ipv4_bind_addresses = "127.0.0.1"
chroot_dir = "/etc/maradns"
recursive_acl = "127.0.0.1/8"
upstream_servers = {}
upstream_servers["."] = "10.1.2.3, 10.2.4.6"
27.Whydoesn'ttheMaraDNS.orgwebpagevalidate?
HTML pages on the MaraDNS.org web site should validate as HTML 4.0 Transitional. However, the CSS will
not validate.
I have designed MaraDNS' web page to be usable and as attractive as possible in any major browser
released in the last ten years. Cross-browser support is more important than strict W3 validation. The
reason why the CSS does not validate is because I need a way to make sure there is always a scrollbar on
the web page, even if the content is not big enough to merit one; this is to avoid the content jumping
from page to page. There is no standard CSS tag that lets me do this. I'm using a non-standard tag to
enable this in Gecko (Firefox's rendering engine); this is enabled by default in Trident (Internet
Explorer's rendering engine). The standards are deficient and blind adherence to them would result in an
inferior web site.
There are also two validation warnings generated by redefinitions which are needed as part of the CSS
filters used to make the site attractive on older browsers with limited CSS support.
On a related note, the reason why I use tables instead of CSS for some of the layout is because Microsoft
Internet Explorer 6 and other browsers do not have support for the max-width CSS property. Without this
property, the web page will not scale down correctly without using tables. Additionally, tables allow a
reasonably attractive header in browsers without CSS support.
28.HowdoMXrecordswork?
How MX records work:
* The mail transport agent (Sendmail, Postfix, Qmail, MS Exchange, etc.) looks up the MX record for the
domain
* For each of the records returned, the MTA (mail transport agent) looks up the IP for the names.
* It will choose, at random, any of the MXes with the lowest priority number.
* Should that server fail, it will try another server with the same priority number.
* Should all MX records with a given priority number fail, the MTA will try sending email to any of the
MX records with the second-lowest priority value.
As an aside, do not have MX records point to CNAMEs.
29.DoesMaraDNShavesupportforSPF?
SPF, or sender policy framework, is method of using DNS that makes it more difficult to forge email.
MaraDNS has full support for SPF, both via TXT records and RFC4408 SPF records.
SPF configuration is beyond the scope of MaraDNS' documentation. However, at the time this FAQ entry was
last updated (July, 2013), information and documentation concerning SPF is available at
http://openspf.org. The BIND examples will work in MaraDNS csv2 zone files as long as the double quotes
(") are replaced by single quotes ('). For example, a SPF TXT record that looks like example.net. IN TXT
"v=spf1 +mx a:colo.example.com/28 -all" in a BIND zone file will look like example.net. TXT 'v=spf1 +mx
a:colo.example.com/28 -all' in a MaraDNS zone file. MaraDNS can also make the corresponding SPF record,
which will have the syntax example.net. SPF 'v=spf1 +mx a:colo.example.com/28 -all'.
Use '\x7e' to put a tilde ("~" character) in a SPF record:
example.com. SPF 'v=spf1 +mx a:colo.example.com/28 '\x7e'all'
30.I'mhavingproblemsresolvingCNAMESIhavesetup.
This is probably because you have set up what MaraDNS calls a dangling CNAME record.
Let us suppose we have a CNAME record without an A record in the local DNS server's database, such as:
google.example.com. CNAME www.google.com.
This record, which is a CNAME record for "google.example.com", points to "www.google.com". Some DNS
servers will recursively look up www.google.com, and render the above record like this:
google.example.com. CNAME www.google.com.
www.google.com. A 66.102.7.104
For security reasons, MaraDNS doesn't do this. Instead, MaraDNS will simply output:
google.example.com. CNAME www.google.com.
Some stub resolvers will be unable to resolve google.example.com as a consequence.
If you set up MaraDNS to resolve CNAMEs thusly, you will get a warning in your logs about having a
dangling CNAME record.
If you want to remove these warnings, add the following to your mararc file:
no_cname_warnings = 1
Information about how to get MaraDNS to resolve dangling CNAME records is in the tutorial file
dangling.html
31.IhaveaNSdelegation,andMaraDNSisdoingstrangethings.
This is only an issue in MaraDNS 1.4. MaraDNS 2.0 does not allow the same IP to both authoritatively and
recursively resolve records.
32.Iamtransferringazonefromanotherserver,buttheNSrecordsarethesestrange"synth-ip"records.
MaraDNS expects, in csv2 zone files, for all delegation NS records to be between the SOA record and the
first non-NS record.
If a zone looks like this:
example.net. +600 soa ns1.example.net.
hostmaster@example.net 10 10800 3600 604800 1080
example.net. +600 mx 10 mail.example.net.
example.net. +600 a 10.2.3.5
example.net. +600 ns ns1.example.net.
example.net. +600 ns ns3.example.net.
mail.example.net. +600 a 10.2.3.7
www.example.net. +600 a 10.2.3.11
Then the NS records will be "synth-ip" records.
The zone should look like this:
example.net. +600 soa ns1.example.net.
hostmaster@example.net 10 10800 3600 604800 1080
example.net. +600 ns ns1.example.net.
example.net. +600 ns ns3.example.net.
example.net. +600 mx 10 mail.example.net.
example.net. +600 a 10.2.3.5
mail.example.net. +600 a 10.2.3.7
www.example.net. +600 a 10.2.3.11
This will remove the "synth-ip" records.
To automate this process, this awk script is useful:
fetchzone whatever.zone.foo 10.1.2.3 | awk '
{if($3 ~ /ns/ || $3 ~ /soa/){print}
else{a = a "\n" $0}}
END{print a}' > zonefile.csv2
Replace "whatever.zone.foo" with the name of the zone you are fetchin 10.1.2.3 with the IP address of the
DNS master, and zonefile.csv2 with the name of the zone file MaraDNS loads.
33.Whereistheroot.hintsfile?
MaraDNS (actually, Deadwood), unlike BIND, does not need a complicated root.hints file in order to have
custom root servers. In order to change the root.hints file, add something like this to your dwood3rc
file:
root_servers["."] = "131.161.247.232,"
root_servers["."] += "208.185.249.250,"
root_servers["."] += "66.227.42.140,"
root_servers["."] += "66.227.42.149,"
root_servers["."] += "65.243.92.254"
Note that there is no "+=" in the first line, and the last line does not have a comma at the end. Read
the recursive tutorial document for more information.
34.ArethereanyplanstouseautoconftobuildMaraDNS?
No.
In more detail, MaraDNS does not use autoconf for the following reasons:
* Autoconf is designed to solve a problem that existed in the mid 1990s but does not exist today: A large
number of different incompatible C compilers and libc implementations. These days, most systems are
using gcc as the compiler and some version of glibc as the libc. There is no longer a need, for
example, to figure out whether a given implementation of getopt() allows '--' options. MaraDNS's
./configure script can be run in only a second or two; compare this to the 3-5 minute process
autoconf's ./configure needs.
* Autoconf leaves GPL-tained files in a program's build tree. MaraDNS is licensed under a BSD license
that is not GPL-compatible, so MaraDNS can not be distributed with these GPL-licensed files.
This leads us to the next question:
35.HowdoIchangethecompilerorcompile-timeflagswithMaraDNS'buildprocess?
To change the compiler used by MaraDNS:
* Run the ./configure script
* Open up the file Makefile with an editor
* Look for a line that starts with CC
* If there is no line that starts with CC, create one just before the line that starts with FLAGS
* Change (or create) that line to look something like CC=gcc296 In this example, the 2.96 version of gcc
is used to compile MaraDNS.
* Note that it is important to not remove anything from this line you do not understand; doing so will
make MaraDNS unable to compile or run. So, if the CC line looks like
CC=gcc $(LDFLAGS) -DNO_FLOCK and you want to compile with gcc 2.96, change the line to look
like CC=gcc296 $(LDFLAGS) -DNO_FLOCK retaining the flags added by the configuration script.
Changing compile-time flags is a similar process:
* Run the ./configure script
* Open up the file Makefile with an editor
* Look for a line that starts with FLAGS
* Change (or create) that line to look something like FLAGS=-O3 In this example, MaraDNS is compiled with
the -O3 option.
* Note that it is important to not remove anything from this line you do not understand; doing so will
make MaraDNS unable to compile or run. So, if the FLAGS line looks like
FLAGS=-O2 -Wall -DSELECT_PROBLEM and you want to compile at optimization level three, change
this line to look like FLAGS=-O2 -Wall -DSELECT_PROBLEM retaining the flags added by the
configuration script. -DSELECT_PROBLEM for example, is needed in the Linux compile or MaraDNS will have
problems with freezing up.
36.WillyoumakeapackagefortheparticularLinuxdistributionIamusing?
No.
There is, however, a CentOS 5-compatible RPM spec file in the build directory.
37.IamusingthenativeWindowsportofMaraDNS,andsomefeaturesarenotworking.
Since Windows 32 does not have some features that *NIX OSes have, the native Windows port does not have
all of the features of the *NIX version of MaraDNS. In particular, the following features are disabled:
* ipv6 (this is actually a mingw32, not a Windows deficiency)
* The chroot_dir mararc variable
* The maradns_gid and maradns_uid mararc variables
* The maxprocs mararc variable
* The synth_soa_serial variable can not have a value of 2
* There is no DNS-over-TCP support
If any of the above features are desired, try compiling MaraDNS using Cygwin. Note that the Cygwin port
of MaraDNS does not have ipv6 support, and that while chroot_dir works in Cygwin, it does not have the
security that the *NIX chroot() call has.
38.MaraDNSisn'tstartingup
This is usually caused by a syntax error in one's mararc file, or by another MaraDNS process already
running. To see what is happening, look at your system log (/var/log/messages in Centos 3) to see what
errors MaraDNS reports. If you do not know how to look at a system log, you can also invoke MaraDNS from
the command line as root; any errors will be visible when starting MaraDNS.
39.YoumakealotofreleasesofMaraDNS;atourISP/ITdepartment,updatingsoftwareisnon-trivial.
Regularly updating software is required to keep something as complicated as a DNS server secure; there is
not a DNS server out there so secure that it never needs to be updated.
Since MaraDNS is finished, updates usually only happen about once a year.
The last security bug which required a MaraDNS update was made before January 30, 2015.
40.Ihavestarrecordsinmyzones,andamhavingproblemswithNXDOMAINs/IPV6resolution
This was a bug in MaraDNS 1.2 which has long since been fixed.
41.IhaveazonewithonlySOA/NSrecords,andthezoneisnotworking.
MaraDNS 1.2 had a bug where it did not correctly process zones without any "normal" records. Upgrade to
MaraDNS 2.0.
42.IamhavingproblemsregisteringmydomainwithAFNIC(theregistrarfor.frdomains)
Because of an issue with AFNIC (who, annoyingly enough, check the RA bit when registering a domain), in
order to register a domain with AFNIC using MaraDNS as your DNS server, the following steps need to be
followed:
* MaraDNS version 1.4 or 2.0 needs to be used; if you're using an older version of MaraDNS, upgrade.
* It is necessary to have recursion disabled, if using MaraDNS 1.4, either by compiling MaraDNS without
recursive support (./configure --authonly ; make), or by making sure MaraDNS does not have recursion
enabled (by not having recursive_acl set in one's MaraDNS 1.4 mararc file)
If one wishes to both register domains with AFNIC and use MaraDNS 1.4 as a recursive DNS server, it is
required to have the recursive server be a separate instance of MaraDNS on a separate IP. It is not
possible to have the same DNS server both send DNS packets in a way that both makes AFNIC happy and
allows recursive queries.
Note also: AFNIC gives warnings about reverse DNS lookups; more information about this issue can be found
in the FAQ entry about reverse DNS mappings (question 7). In addition, AFNIC requires DNS-over-TCP to
work; information on configuring MaraDNS to have this can be found in the DNS-over-TCP tutorial.
43.Ican'tseethefullanswersforsubdomainsIhavedelegated
To have the subdomains be visible to MaraDNS 1.4 recursive nameservers, add the following to your mararc
file:
recurse_delegation = 1
44.MaraDNS1hasaproblemresolvingadomain
This issue should be fixed in MaraDNS 2.0.
Here's what happening: I have rewritten the recursive resolver for MaraDNS. The old code was always
designed to be a placeholder until I wrote a new recursive resolver.
The new recursive resolver is called "Deadwood"; right now it's fully functional and part of MaraDNS 2.0.
More information is here:
http://maradns.blogspot.com/search/label/Deadwoodhttp://maradns.samiam.org/deadwood/
Since the old recursive code is a bit difficult to maintain, and since I in the process of rewriting the
recursive code, my rule is that I will only resolve security issues with MaraDNS 1.0's recursive
resolver.
45.MaraDNS1.2hadissueswithNXDOMAINSandcasesensitivity.
There was a known bug in MaraDNS 1.2.12 where, should a client ask for a non-existent record in all caps,
MaraDNS 1.2.12 will return a NXDOMAIN instead of a "not there" reply. Upgrade to 2.0.
46.CanMaraDNSofferprotectionfromphishingandmalicioussites?
Deadwood can block up to about 20,000 domains. More details are in the Deadwood FAQ.
47.Doesmaradnssupportstar(wildcard)records?
Yes.
MaraDNS supports both having stars at the beginning of records and the end of records. For example, to
have anything.example.com. have the IP 10.1.2.3, add this line to the zone file for example.com:
*.example.com. A 10.1.2.3
To have stars at the end of records, csv2_default_zonefile has to be set. The mararc parameter
bind_star_handling affects how star records are handled. More information is in the mararc man page.
48.I'mhavingproblemsusingMaraDNSwithsome*NIXcommandlineapplicationsliketelnet.
Some *NIX command line networking applications, such as telnet and ssh, try to do either a reverse DNS
lookup (IP-to-host name conversion) or an IPv6 lookup. This slows things down and sometimes causes the
applications to not work at all.
For people who do not need IPv6 lookups, add the following line to one's mararc file to have MaraDNS
respond to all IPv6 lookups with a bogus "not found" reply:
reject_aaaa = 1
If knowing the hostname a given IP has isn't important, these kinds of lookups can also be disabled:
reject_ptr = 1
49.MyvirusscannerreportsthatMaraDNSorDeadwoodhasavirus
This can be caused either by a poorly written anti-virus program reporting a false positive, or because a
virus on your system has infected your copy of MaraDNS/Deadwood.
Please use GPG to verify that the file which your scanner reports having a virus in has not been altered.
In addition, please scan the file with AVG (free for non-commercial use) to verify your virus scanner has
not reported a false positive.
If you have verified the GPG signature of the program and AVG reports a virus, please let us know with a
Github issue. Otherwise, please use a better virus scanner and make sure there are no viruses on your
computer.
50.IcannotsubscribetotheMaraDNSmailinglistPleasenotethatthemailinglistisnolongerusedtohandleMaraDNSsupportrequests.PleasefileaGithubissueathttps://github.com/samboy/MaraDNS/issuestofileaMaraDNSbugreport.
The procedure for subscribing to the mailing list is as follows:
* Send an email to list-request@maradns.org with "Subscribe" as the subject, or an email to list-
subscribe@maradns.org
* You will get an email from list-request@maradns.org asking you to confirm your subscription. This can
be done by replying to the message, or, more simply, by clicking on the link in the message.
* Once you click on that link, click on the button marked "subscribe to list list"
* You will now get a message stating 'Welcome to the "list" mailing list'.
* Note that the mailing list is moderated and only relevant MaraDNS announcements are approved. People
who need help should read the manuals or search the MaraDNS webpage for support.
If you get an email from list-request@maradns.org with the subject "The results of your email commands",
you did not correctly send an email to list-request@maradns.org with the subject "Subscribe".
If you do not get the email from list-request@maradns.org asking you for a confirmation, ensure that this
email is not in your "spam" or "junk mail" folder. If you are unable to get these emails at your email
address, please get a gmail email account, which can successfully subscribe to the MaraDNS mailing list.
Note that subscription confirmation emails may be in Gmail's "promotions" tab.
51.HowdoesMaraDNSrespondtoEDNS(RFC2671)packets?
MaraDNS 2 (both the authoritative maradns server and the recursive Deadwood server) responds to EDNS
packets by ignoring the OPT record and acting as if it the packet did not have an OPT record.
MicroDNS (available in the tools/misc directory of any MaraDNS 2 release) responds to EDNS queries the
same way Deadwood 2.9.03 did: By giving back "NOTIMPL" instead of answering the query with the default
IP. NanoDNS, in the interest of minimizing code side, responds to EDNS requests by returning NOTIMPL in
the header, giving the OPT query in the AN section of the response, and giving the default IP in the AR
section of the DNS reply packet.
52.HowtoIgetMaraDNStoalwaysgivethesameIPtoallDNSqueries?
There are three ways to have MaraDNS always give the same IP in reply to any DNS query given to it:
* The best way to do this is to set up a default zonefile that causes any and all A queries to always
give the IP (and also allows all AAAA queries to always give out the same IP6, all SPF or TXT queries
to give out the same SPF record, etc.).
* Another possibility, if someone just wants a simple DNS server that always gives out the same IP
address to any and all DNS queries, is to use the MicroDNS program, available in tools/misc, as well as
having its own web page.
* If MicroDNS is too bloated, there is also NanoDNS, which I will include the source code of below:
/*Placed in the public domain by Sam Trenholme*/
#include <arpa/inet.h>
#include <string.h>
#include <stdint.h>
#define Z struct sockaddr
#define Y sizeof(d)
int main(int a,char **b){uint32_t i;char q[512]
,p[17]="\xc0\f\0\x01\0\x01\0\0\0\0\0\x04";if(a>
1){struct sockaddr_in d;socklen_t f=511;bzero(&
d,Y);a=socket(AF_INET,SOCK_DGRAM,0);*((uint32_t
*)(p+12))=inet_addr(b[1]);d.sin_family=AF_INET;
d.sin_port=htons(53);bind(a,(Z*)&d,Y);for(;;){i
=recvfrom(a,q,255,0,(Z*)&d,&f);if(i>9&&q[2]>=0)
{q[2]|=128;q[11]?q[3]|=4:1;q[7]++;memcpy(q+i,p,
16);sendto(a,q,i+16,0,(Z*)&d,Y);}}}return 0;}
NanoDNS takes one argument: The IP we return. This program binds to all IP addresses a given machine has
on the UDP DNS port (port 53). For example, to make a DNS server that binds to all IPs your system has
and return the IP 10.11.12.13 to any UDP DNS queries sent to it, compile the above C program, call it
NanoDNS, and invoke it with NanoDNS 10.11.12.13 Note that NanoDNS does not daemonize, nor log anything,
nor have any other space-wasting features.
WhydidyouchangeMaraDNS'tagline?
I have changed MaraDNS' tagline from "MaraDNS: A security-aware DNS server" to "MaraDNS: A small open-
source DNS server" because MaraDNS does not support DNSSEC. I have blogged about this:
http://samiam.org/blog/20120326.htmlHowdoyoustopMaraDNSfromtakingpartinadistributeddenial-of-serviceattack?
While I do not have time to implement rate limiting, CentOS 6 does support response rate limiting at the
firewall level. The following iptables commands allow a given IP to only send MaraDNS/Deadwood 20 DNS
queries every four seconds:
iptables -A INPUT -p udp --dport 53 -m state --state NEW -m recent --set --name DDOS --rsource
iptables -A INPUT -p udp --dport 53 -m state --state NEW -m recent --update --seconds 4 --hitcount 20
--name DDOS --rsource -j DROP
To verify they are applied:
iptables --list
To save these commands in CentOS so they are applied at system boot time:
iptables-save > /etc/sysconfig/iptables
Disclaimer
These incantations work in CentOS 6 but may or may not work in other versions of Linux. I do not support
non-CentOS6 Linux installs of MaraDNS.
WhataboutDNS-over-TCP?
For people who want DNS-over-TCP, instructions are in the DNS-over-TCP tutorial. Note that Windows users
will have to use Cygwin to have DNS-over-TCP.
However, DNS-over-TCP is not necessary. DNS-over-TCP is optional as per section 6.1.3.2 of RFC1123; any
program or web service that considers no DNS-over-TCP an error is not RFC-compliant.
Not having DNS-over-TCP is more secure, because it gives attackers a smaller surface to attack.
HowdoIuseMaraDNSwithsystemd?
While I like systemd, it is not part of CentOS 6 nor, obviously, Windows 7. That in mind, I have no plans
to support systemd until 2017, when I plan to update MaraDNS' supported operating systems.
However, Tomasz Torcz has kindly made some systemd files for MaraDNS, which people are free to use.
As an aside, I do not like the fact that Debian will probably not make systemd the default init; I do not
think this kind of fragmentation is good for Linux.
Whydoesn'tMaraDNSuseIP_FREEBIND?
IP_FREEBIND is a non-POSIX Linux-specific extension to POSIX's netinet/in.h, and, as such, has no place
in MaraDNS' code. MaraDNS strives to use POSIX-compliant calls so that it can compile on as many systems
as possible.
When I say that Windows 7 and CentOS 6 are the only supported operating systems for MaraDNS, this does
not mean that MaraDNS will not compile and run on other systems; it merely means that I can not provide
support for Github bug reports for people who want to run MaraDNS in Minix, one of the open-source BSD
variants, or what not.
IsthereawebinterfaceforMaraDNS?
The Kloxo-MR control panel has MaraDNS support.
Whatdoesthemessage“don’tforgetthetrailingdot”mean?
It means to not forget the tailing dot.
Hostnames in zone files need to be properly terminated; if a hostname is in the form “foo.example.com”,
this name will not parse and return an error with a note to not forget the trailing dot.
To fix this, put a trailing dot at the end of the hostname, so it looks like “foo.example.com.” (observe
that dot at the end) instead of “foo.example.com”
DoesMaraDNSsupportnewertopleveldomains?
MaraDNS does not impose any limitations on the top level domain used in zone files and other places, as
is fully compatible with newer top level domains like “today.”
Note that, if using an internationalized domain name, it needs to be translated in to Punycode first. For
example, if using the domain name “ñ.com.”, it needs to be in the form “xn--ida.com.” in MaraDNS’ mararc
and zone files.
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