Sponsor:

Your company here — click to reach over 10,000 unique daily visitors

maradns - Man Page

DNS server

Erre con erre cigarro 
Erre con erre barril 
Rápido ruedan los carros 
En el ferrocarril

Synopsis

maradns [ -v | -f mararc_file_location ]

Table of Contents

This man page has the following sections:

Name  
Synopsis 
Table of Contents 
Description 
Usage 
Firewall Configuration 
Frequently Asked Questions 
Bugs 
Unimplemented Features 
Legal Disclaimer 
Authors

Description

maradns is a DNS server written with security, simplicity, and performance in  mind.

maradns has two forms of arguments, both of which are optional.

The first is the location of a mararc file which MaraDNS obtains all configuration information from. The  default location of this file is /etc/mararc. This is specified in the form maradns -f mararc_file_location;

mararc_file_location is the location of the mararc file.

It is also possible to have MaraDNS display the version number and  exit. This is specified by invoking maradns in the form maradns -v or maradns --version

Usage

MaraDNS consists of two programs: maradns, an authoritative-only  nameserver, and Deadwood, a recursive name server. Deadwood has its own  man page.

In order for MaraDNS to function as an authoritative nameserver, two or  more files need to be set up: the mararc file and one or more "csv2"  (or "csv1") zone files.

The format of a csv2 zone file can be obtained from the csv2(5) manual page. The configuration format of the mararc file can be  obtained from the mararc(5) manual page.

Please note that, in order to reload a zone file, it is necessary to  restart MaraDNS and reload all zone files. MaraDNS uses a hash data  format which loads records very quickly from memory, but requires a  restart to update.

In order to have MaraDNS run as a daemon, the duende program is used to  daemonize MaraDNS. See the duende(8) manual page for details.

Firewall Configuration

When using the maradns authoritative nameserver, allow UDP connections  from all hosts on the internet to UDP port 53 for the IP that the  authoritative nameserver uses.

When using the Deadwood recursive nameserver:  

Deadwood uses a strong secure RNG (RadioGatun[32]) for both the query  (16 bits of entropy) and the source port of the query (12 bits of  entropy). This makes spoofing replies to a Deadwood recursive server  more difficult, since the attacker has only a one in 250 million chance  that a given spoofed reply will be considered valid.

Frequently Asked Questions

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?

61. Can MaraDNS handle IDN domain names?

ANSWERS

1. I'm using an older version of MaraDNS

Upgrade to MaraDNS 2.0. Here is an upgrade guide.

MaraDNS 1 is no longer supported; support ended on June 21, 2015.  

2. How do I try out MaraDNS?

Read the quick start guide, which is the file named 0QuickStart in the  MaraDNS distribution.

3. What license is MaraDNS released under?

MaraDNS is released with the following two-clause BSD-type license:

Copyright (c) 2002-2016 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. How do I report bugs in MaraDNS?

Post your bug report as a Github issue.  

5. Some of the postings to the mailing list do not talk about MaraDNS!

As of September 2013, the mailing list has become moderated and only  postings on the mailing list are relevant MaraDNS announcements.  

6. How do I get off the mailing list?

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. How do I set up reverse DNS on MaraDNS?

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. I am on a slow network, and Deadwood can not process recursive queries

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. When I try to run MaraDNS, I get a cryptic error message.

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. After I start MaraDNS, I can not see the process when I run  netstat -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. What string library does MaraDNS use?

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. Why does MaraDNS use a multi-threaded model?

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. I feel that XXX feature should be added to MaraDNS

There are no plans to add new features to MaraDNS or Deadwood at this  time.  

14. I feel that MaraDNS should use another documentation format

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. Is there any process I need to follow to add a patch to MaraDNS?

I no longer accept third party patches  

16. Can MaraDNS act as a primary nameserver?

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. Can MaraDNS act as a secondary nameserver?

Yes.

Please read the  DNS slave document, which is part of the MaraDNS  tutorial.  

18. What is the difference between an authoritative and a recursive  DNS server?

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. The fetchzone client isn't allowing me to add certain  hostnames to my zone

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:  

20. Is MaraDNS portable?

MaraDNS is developed in CentOS 6 and Windows 7. MaraDNS may or may not  compile and run on other systems.  

21. Can I use MaraDNS in Windows?

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. MaraDNS freezes up after being used for a while

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. What kind of Python integration does MaraDNS have

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 in Esperanto?

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. How scalable is MaraDNS?

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.    <h2>26. I am having problems setting upstream_servers</h2>  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. Why doesn't the MaraDNS.org web page validate?

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. How do MX records work?

How MX records work:  

As an aside, do not have MX records point to CNAMEs.  

29. Does MaraDNS have support for SPF?

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'm having problems resolving CNAMES I have set up.

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. I have a NS delegation, and MaraDNS is doing strange things.

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. I am transferring a zone from another server, but the NS records  are these strange 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. Where is the root.hints file?

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. Are there any plans to use autoconf to build MaraDNS?

No.

In more detail, MaraDNS does not use autoconf for the following  reasons:  

This leads us to the next question:  

35. How do I change the compiler or compile-time flags with  MaraDNS' build process?

To change the compiler used by MaraDNS:  

Changing compile-time flags is a similar process:  

36. Will you make a package for the particular Linux distribution I  am using?

No.

There is, however, a CentOS 5-compatible RPM spec file in the build  directory.  

37. I am using the native Windows port of MaraDNS, and some features  are not working.

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:

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. MaraDNS isn't starting up

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. You make a lot of releases of MaraDNS; at our ISP/IT department,  updating software is non-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  September 28, 2015.  

40. I have star records in my zones, and am having problems with  NXDOMAINs/IPV6 resolution

This was a bug in MaraDNS 1.2 which has long since been fixed.  

41. I have a zone with only SOA/NS records, and the zone is not working.

MaraDNS 1.2 had a bug where it did not correctly process zones without  any "normal" records. Upgrade to MaraDNS 2.0.  

42. I am having problems registering my domain with AFNIC (the  registrar for .fr domains)

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:  

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. I can't see the full answers for subdomains I have delegated

To have the subdomains be visible to MaraDNS 1.4 recursive nameservers,  add the following to your mararc file:

recurse_delegation = 1  

44. MaraDNS 1 has a problem resolving a domain

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/Deadwood

http://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. MaraDNS 1.2 had issues with NXDOMAINS and case sensitivity.

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. Can MaraDNS offer protection from phishing and malicious sites?

Deadwood can block up to about 20,000 domains. More details are in the  Deadwood FAQ.  

47. Does maradns support star (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'm having problems using MaraDNS with some *NIX command line  applications like telnet.

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. My virus scanner reports that MaraDNS or Deadwood has a virus

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. I can not subscribe to the MaraDNS mailing list

Please note that the mailing list is no longer used to handle MaraDNS support requests. Please file a Github issue at  https://github.com/samboy/MaraDNS/issues to file a MaraDNS bug report."

The procedure for subscribing to the mailing list is as follows:  

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. How does MaraDNS respond to EDNS (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. How to I get MaraDNS to always give the same IP to all DNS queries?

There are three ways to have MaraDNS always give the same IP in reply  to any DNS query given to it:  

#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.

Why did you change MaraDNS' 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:

How do you stop MaraDNS from taking part in a distributed  denial-of-service attack?

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.  

What about DNS-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.  

How do I use MaraDNS with systemd?

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.  

Why doesn't MaraDNS use IP_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.  

Is there a web interface for MaraDNS?

The Kloxo-MR control panel has MaraDNS support.  

What does the message “don’t forget the trailing dot” 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”  

Does MaraDNS support newer top level domains?

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.  

Can MaraDNS handle IDN domain names?

Yes, but the internationalized domain name (IDN) 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.

Bugs

In the unusual case of having a csv2 zone file with Macintosh-style  newlines (as opposed to DOS or UNIX newlines), while the file will  parse, any errors in the file will be reported as being on line 1.

The system startup script included with MaraDNS assumes that the only  MaraDNS processes running are started by the script; it stops all MaraDNS processes running on the server when asked to stop MaraDNS.

MaraDNS needs to use the zoneserver program to serve DNS records over TCP. See zoneserver(8) for usage information.

MaraDNS does not use the zone file ("master file") format specified in  chapter 5 of RFC1035.

MaraDNS default behavior with star records is not RFC-compliant. In  more detail, if a wildcard MX record exists in the form  "*.example.com", and there is an A record for "www.example.com", but no  MX record for "www.example.com", the correct behavior (based on RFC1034  §4.3.3) is to return "no host" (nothing in the answer section, SOA in  the authority section, 0 result code) for a MX request to  "www.example.com". Instead, MaraDNS returns the MX record attached to  "*.example.com". This can be changed by setting bind_star_handling to  1.

Star records (what RFC1034 calls "wildcards") can not be attached to NS  records.

MaraDNS, like every other known DNS implementation, only supports a  QDCOUNT of 0 or 1.

Unimplemented Features

These are features which I do not plan to implement in MaraDNS.

MaraDNS does not have a disk-based caching scheme for authoritative  zones.

MaraDNS' UDP server only loads zone files while MaraDNS is first  started. UDP Zone information can only be updated by stopping MaraDNS,  and restarting MaraDNS again. Note that TCP zone files are loaded from  the filesystem at the time the client requests a zone.

MaraDNS does not have support for allowing given host names to only  resolve for a limited range of IPs querying the DNS server, or for host  names to resolve differently, depending on the IP querying the host  name.

MaraDNS only allows wildcards at the beginning or end of a host name.  E.g. names with wildcards like "foo.*.example.com". "www.*" will work,  however, if a default zonefile is set up. Likewise, MaraDNS does not  have regular expression hostname substitution.

MaraDNS does not have support for MRTG or any other SNMP-based logging  mechanism.

Authors

Sam Trenholme (http://www.samiam.org) is responsible for this man page.

MaraDNS is written by me, Sam Trenholme, with a little help from my  friends. Naturally, all errors in MaraDNS are my own (but read the  disclaimer above).

Here is a partial list of people who have provided assistance:

Floh has generously set up a FreeBSD 4, FreeBSD 6, and Mac OS X system  so that I can port MaraDNS to more platforms.

Albert Lee has provided countless bug reports, and, nicely enough,  patches to fix said bugs. He has also made improvements to the code in  the tcp "zoneserver".

Franky Van Liedekerke has provided much invaluable assistance. As just  one example, he provided invaluable assistance in getting MaraDNS to  compile on Solaris. In addition, he has provided much valuable SQA  help.

Christian Kurz, who has provided invaluable bug reports, especially  when I had to re-implement the core hashing algorithm.

Remmy, who is providing both the web space and a mailing list for  maradns.org.

Phil Homewood, who provided invaluable assistance with finding and  fixing bugs in the authoritative portion of the MaraDNS server. He  helped me plug memory leaks, find uninitialized variables being used,  and found a number of bugs I was unable to find.

Albert Prats kindly provided Spanish translations for various text  files.

Shin Zukeran provided a patch to recursive.c which properly makes a  normal null-terminated string from a js_string object, to send as an  argument to open() so we can get the rijndael key for the PRNG.

D Richard Felker III has provided invaluable bug reports. By looking at  his bug reports, I have been able to hunt down and fix many problems  that the recursive nameserver had, in addition to at least one problem  with the authoritative nameserver.

Ole Tange has also given me many valuable MaraDNS bug reports.

Florin Iucha provided a tip in the FAQ for how to compile MaraDNS on  OpenBSD.

Roy Arends (one of the BIND developers, as it turns out) found a  serious security problem with MaraDNS, where MaraDNS would answer  answers, and pointed it out to me.

Code used as the basis for the psudo-random-number generator was  written by Vincent Rijmen, Antoon Bosselaers, and Paulo Barreto. I  appreciate these programmers making the code public domain, which is  the only license under which I can add code to MaraDNS under.

Ross Johnson and others have made a Win32 port of the Pthreads library;  this has made a native win32 port of MaraDNS possible.

I also appreciate the work of Dr. Brian Gladman and Fritz Schneider,  who have both written independent implementations of AES from which I  obtained test vectors. With the help of their hard work, I was able to  discover a subtle security problem that previous releases of MaraDNS  had.  

Referenced By

askmara(1), fetchzone(1), getzone(1), zoneserver(8).

January 2002 MaraDNS reference