net/unbound/files/README.md

   1 # Unbound Recursive DNS Server with UCI
   2
   3 ## Unbound Description
   4 [Unbound](https://www.unbound.net/) is a validating, recursive, and caching DNS resolver. The C implementation of Unbound is developed and maintained by [NLnet Labs](https://www.nlnetlabs.nl/). It is based on ideas and algorithms taken from a java prototype developed by Verisign labs, Nominet, Kirei and ep.net. Unbound is designed as a set of modular components, so that also DNSSEC (secure DNS) validation and stub-resolvers (that do not run as a server, but are linked into an application) are easily possible.
   5
   6 ## Package Overview
   7 Unbound may be useful on consumer grade embedded hardware. It is _intended_ to be a recursive resolver only. [NLnet Labs NSD](https://www.nlnetlabs.nl/projects/nsd/) is _intended_ for the authoritative task. This is different than [ISC Bind](https://www.isc.org/downloads/bind/) and its inclusive functions. Unbound configuration effort and memory consumption may be easier to control. A consumer could have their own recursive resolver with 8/64 MB router, and remove potential issues from forwarding resolvers outside of their control.
   8
   9 This package builds on Unbounds capabilities with OpenWrt UCI. Not every Unbound option is in UCI, but rather, UCI simplifies the combination of related options. Unbounds native options are bundled and balanced within a smaller set of choices. Options include resources, DNSSEC, access control, and some TTL tweaking. The UCI also provides an escape option and work at the raw "unbound.conf" level.
  10
  11 ## HOW TO Adblocking
  12 The UCI scripts will work with [net/adblock 2.3+](https://github.com/openwrt/packages/blob/master/net/adblock/files/README.md), if it is installed and enabled. Its all detected and integrated automatically. In brief, the adblock scripts create distinct local-zone files that are simply included in the unbound conf file during UCI generation. If you don't want this, then disable adblock or reconfigure adblock to not send these files to Unbound.
  13
  14 ## HOW TO Integrate with DHCP
  15 Some UCI options and scripts help Unbound to work with DHCP servers to load the local DNS. The examples provided here are serial dnsmasq-unbound, parallel dnsmasq-unbound, and unbound scripted with odhcpd.
  16
  17 ### Serial dnsmasq
  18 In this case, dnsmasq is not changed *much* with respect to the default OpenWRT/LEDE configuration. Here dnsmasq is forced to use the local Unbound instance as the lone upstream DNS server, instead of your ISP. This may be the easiest implementation, but performance degradation can occur in high volume networks. dnsmasq and Unbound effectively have the same information in memory, and all transfers are double handled.
  19
  20 **/etc/config/unbound**:
  21
  22 ```
  23 config unbound
  24   option add_local_fqdn '0'
  25   option add_wan_fqdn '0'
  26   option dhcp_link 'none'
  27   # dnsmasq should not forward your domain to unbound, but if...
  28   option domain 'yourdomain'
  29   option domain_type 'refuse'
  30   option listen_port '1053'
  31   ...
  32 ```
  33
  34 **/etc/config/dhcp**:
  35
  36 ```
  37 config dnsmasq
  38   option domain 'yourdomain'
  39   option noresolv '1'
  40   option resolvfile '/tmp/resolv.conf.auto'
  41   option port '53'
  42   list server '127.0.0.1#1053'
  43   list server '::1#1053'
  44   ...
  45 ```
  46
  47 ### Parallel dnsmasq
  48 In this case, Unbound serves your local network directly for all purposes. It will look over to dnsmasq for DHCP-DNS resolution. Unbound is generally accessible on port 53, and dnsmasq is only accessed at 127.0.0.1:1053 by Unbound. Although you can dig/drill/nslookup remotely with the proper directives.
  49
  50 **/etc/config/unbound**:
  51
  52 ```
  53 config unbound
  54   option dhcp_link 'dnsmasq'
  55   option listen_port '53'
  56   ...
  57 ```
  58
  59 **/etc/config/dhcp**:
  60
  61 ```
  62 config dnsmasq
  63   option domain 'yourdomain'
  64   option noresolv '1'
  65   option resolvfile '/tmp/resolv.conf.auto'
  66   option port '1053'
  67   ...
  68
  69 config dhcp 'lan'
  70   # dnsmasq may not issue DNS option if not std. configuration
  71   list dhcp_option 'option:dns-server,0.0.0.0'
  72   ...
  73 ```
  74
  75 ### Unbound and odhcpd
  76 You may ask, "can Unbound replace dnsmasq?" You can have DHCP-DNS records with Unbound and odhcpd only. The UCI scripts will allow Unbound to act like dnsmasq. When odhcpd configures each DHCP lease, it will call a script. The script provided with Unbound will read the lease file for DHCP-DNS records. You **must install** `unbound-control`, because the lease records are added and removed without starting, stopping, flushing cache, or re-writing conf files. (_restart overhead can be excessive with even a few mobile devices._)
  77
  78 Don't forget to disable or uninstall dnsmasq when you don't intend to use it. Strange results may occur. If you want to use default dnsmasq+odhcpd and add Unbound on top, then use the dnsmasq-serial or dnsmasq-parallel methods above.
  79
  80 **/etc/config/unbound**:
  81
  82 ```
  83 config unbound
  84   # name your router in DNS
  85   option add_local_fqdn '1'
  86   option add_wan_fqdn '1'
  87   option dhcp_link 'odhcpd'
  88   # add SLAAC inferred from DHCPv4
  89   option dhcp4_slaac6 '1'
  90   option domain 'lan'
  91   option domain_type 'static'
  92   option listen_port '53'
  93   option rebind_protection '1'
  94   # install unbound-control and set this
  95   option unbound_control '1'
  96   ...
  97 ```
  98
  99 **/etc/config/dhcp**:
 100
 101 ```
 102 config dhcp 'lan'
 103   option dhcpv4 'server'
 104   option dhcpv6 'server'
 105   option interface 'lan'
 106   option leasetime '12h'
 107   option ra 'server'
 108   option ra_management '1'
 109   # odhcpd should issue ULA [fd00::/8] by default
 110   ...
 111
 112 config odhcpd 'odhcpd'
 113   option maindhcp '1'
 114   option leasefile '/var/lib/odhcpd/dhcp.leases'
 115   # this is where the magic happens
 116   option leasetrigger '/usr/lib/unbound/odhcpd.sh'
 117 ```
 118
 119 ## HOW TO Manual Override
 120 Yes, there is a UCI to disable the rest of Unbound UCI. However, OpenWrt or LEDE are targeted at embedded machines with flash ROM. The initialization scripts do a few things to protect flash ROM.
 121
 122 ### Completely Manual (almost)
 123 All of `/etc/unbound` (persistent, ROM) is copied to `/var/lib/unbound` (tmpfs, RAM). Edit your manual `/etc/unbound/unbound.conf` to reference this `/var/lib/unbound` location for included files. Note in preparation for a jail, `/var/lib/unbound` is `chown unbound`. Configure for security in`/etc/unbound/unbound.conf` with options `username:unbound` and `chroot:/var/lib/unbound`.
 124
 125 Keep the DNSKEY updated with your choice of flash activity. `root.key` maintenance for DNSKEY RFC5011 would be hard on flash. Unbound natively updates frequently. It also creates and destroys working files in the process. In `/var/lib/unbound` this is no problem, but it would be gone at the next reboot. If you have DNSSEC (validator) active, then you should consider the age UCI option. Choose how many days to copy from `/var/lib/unbound/root.key` (tmpfs) to `/etc/unbound/root.key` (flash).
 126
 127 **/etc/config/unbound**:
 128
 129 ```
 130 config unbound
 131   option manual_conf '1'
 132   option root_age '9'
 133   # end
 134 ```
 135
 136 ### Hybrid Manual/UCI
 137 You like the UCI. Yet, you need to add some difficult to standardize options, or just are not ready to make a UCI request yet. The files `/etc/unbound/unbound_srv.conf` and `/etc/unbound/unbound_ext.conf` will be copied to Unbounds chroot directory and included during auto generation.
 138
 139 The former will be added to the end of the `server:` clause. The later will be added to the end of the file for extended `forward:` and `view:` clauses. You can also disable unbound-control in the UCI which only allows "localhost" connections unencrypted, and then add an encrypted remote `control:` clause.
 140
 141 ## Complete List of UCI Options
 142 **/etc/config/unbound**:
 143
 144 ```
 145 config unbound
 146   Currently only one instance is supported.
 147
 148   option add_extra_dns '0'
 149     Level. Execute traditional DNS overrides found in `/etc/config/dhcp`.
 150     Optional so you may use other Unbound conf or redirect to NSD instance.
 151     0 - Ignore `/etc/config/dhcp`
 152     1 - Use only 'domain' clause (host records)
 153     2 - Use 'domain', 'mxhost', and 'srvhost' clauses
 154     3 - Use all of 'domain', 'mxhost', 'srvhost', and 'cname' clauses
 155
 156   option add_local_fqdn '0'
 157     Level. This puts your routers host name in the LAN (local) DNS.
 158     Each level is more detailed and comprehensive.
 159     0 - Disabled
 160     1 - Host Name on only the primary address
 161     2 - Host Name on all addresses found (except link)
 162     3 - FQDN and host name on all addresses (except link)
 163     4 - Above and interfaces named <iface>.<hostname>.<domain>
 164
 165   option add_wan_fqdn '0'
 166     Level. Same as previous option only this applies to the WAN. WAN
 167     are inferred by a UCI `config dhcp` entry that contains the line
 168     option ignore '1'.
 169
 170   option dns64 '0'
 171     Boolean. Enable DNS64 through Unbound in order to bridge networks
 172     that are IPV6 only and IPV4 only (see RFC6052).
 173
 174   option dns64_prefix '64:ff9b::/96'
 175     IPV6 Prefix. The IPV6 prefix wrapped on the IPV4 address for DNS64.
 176     You should use RFC6052 "well known" address, unless you also
 177     redirect to a proxy or gateway for your NAT64.
 178
 179   option dhcp_link 'none'
 180     Program Name. Link to one of the supported programs we have scripts
 181     for. You may also need to install a trigger script in the DHCP
 182     servers configuration. See HOW TO above.
 183
 184   option dhcp4_slaac6 '0'
 185     Boolean. Some DHCP servers do this natively (dnsmasq). Otherwise
 186     the script provided with this package will try to fabricate SLAAC
 187     IP6 addresses from DHCPv4 MAC records.
 188
 189   option domain 'lan'
 190     Unbound local-zone: <domain> <type>. This is used to suffix all
 191     host records, and maintain a local zone. When dnsmasq is dhcp_link
 192     however, then this option is ignored (dnsmasq does it all).
 193
 194   option domain_type 'static'
 195     Unbound local-zone: <domain> <type>. This allows you to lock
 196     down or allow forwarding of your domain, your router host name
 197     without suffix, and leakage of RFC6762 "local."
 198
 199   option edns_size '1280'
 200     Bytes. Extended DNS is necessary for DNSSEC. However, it can run
 201     into MTU issues. Use this size in bytes to manage drop outs.
 202
 203   option extended_luci '0'
 204     Boolean. Extends a tab hierarchy in LuCI for advanced congfiguration.
 205
 206   option extended_stats '0'
 207     Boolean. extended statistics are printed from unbound-control.
 208     Keeping track of more statistics takes time.
 209
 210   option hide_binddata '1'
 211     Boolean. If enabled version.server, version.bind, id.server, and
 212     hostname.bind queries are refused.
 213
 214   option listen_port '53'
 215     Port. Incoming. Where Unbound will listen for queries.
 216
 217   option localservice '1'
 218     Boolean. Prevent DNS amplification attacks. Only provide access to
 219     Unbound from subnets this machine has interfaces on.
 220
 221   option manual_conf '0'
 222     Boolean. Skip all this UCI nonsense. Manually edit the
 223     configuration. Make changes to /etc/unbound/unbound.conf.
 224
 225   option protocol 'mixed'
 226     Unbound can limit its protocol used for recursive queries.
 227     Set 'ip4_only' to avoid issues if you do not have native IP6.
 228     Set 'ip6_prefer' to possibly improve performance as well as
 229     not consume NAT paths for the client computers.
 230     Do not use 'ip6_only' unless testing.
 231
 232   option query_minimize '0'
 233     Boolean. Enable a minor privacy option. Don't let each server know
 234     the next recursion. Query one piece at a time.
 235
 236   option query_min_strict '0'
 237     Boolean. Query minimize is best effort and will fall back to normal
 238     when it must. This option prevents the fall back, but less than
 239     standard name servers will fail to resolve their domains.
 240
 241   option rebind_localhost '0'
 242     Boolean. Prevent loopback "127.0.0.0/8" or "::1/128" responses.
 243     These may used by black hole servers for good purposes like
 244     ad-blocking or parental access control. Obviously these responses
 245     also can be used to for bad purposes.
 246
 247   option rebind_protection '1'
 248     Boolean. Prevent RFC 1918 Reponses from global DNS. Example a
 249     poisoned reponse within "192.168.0.0/24" could be used to turn a
 250     local browser into an external attack proxy server.
 251
 252   option recursion 'passive'
 253     Unbound has numerous options for how it recurses. This UCI combines
 254     them into "passive," "aggressive," or Unbound's own "default."
 255     Passive is easy on resources, but slower until cache fills.
 256
 257   option resource 'small'
 258     Unbound has numerous options for resources. This UCI gives "tiny,"
 259     "small," "medium," and "large." Medium is most like the compiled
 260     defaults with a bit of balancing. Tiny is close to the published
 261     memory restricted configuration. Small 1/2 medium, and large 2x.
 262
 263   option root_age '9'
 264     Days. >90 Disables. Age limit for Unbound root data like root
 265     DNSSEC key. Unbound uses RFC 5011 to manage root key. This could
 266     harm flash ROM. This activity is mapped to "tmpfs," but every so
 267     often it needs to be copied back to flash for the next reboot.
 268
 269   option ttl_min '120'
 270     Seconds. Minimum TTL in cache. Recursion can be expensive without
 271     cache. A low TTL is normal for server migration. A low TTL can be
 272     abused for snoop-vertising (DNS hit counts; recording query IP).
 273     Typical to configure maybe 0~300, but 1800 is the maximum accepted.
 274
 275   option unbound_control '0'
 276     Level. Enables unbound-control application access ports.
 277     0 - No unbound-control Access, or add your own in 'unbound_ext.conf'
 278     1 - Unencrypted Local Host Access
 279     2 - SSL Local Host Access; auto unbound-control-setup if available
 280     3 - SSL Network Access; auto unbound-control-setup if available
 281     4 - SSL Network Access; static key/pem files must already exist
 282
 283   option validator '0'
 284     Boolean. Enable DNSSEC. Unbound names this the "validator" module.
 285
 286   option validator_ntp '1'
 287     Boolean. Disable DNSSEC time checks at boot. Once NTP confirms
 288     global real time, then DNSSEC is restarted at full strength. Many
 289     embedded devices don't have a real time power off clock. NTP needs
 290     DNS to resolve servers. This works around the chicken-and-egg.
 291
 292   list domain_insecure 'www.example.com'
 293     Domain. Domains that you wish to skip DNSSEC. Your DHCP
 294     domains and pointers will get this automatically.
 295
 296   list trigger 'lan' 'wan'
 297     Interface (logical). This option is a work around for netifd/procd
 298     interaction with WAN DHCPv6. Minor RA or DHCP changes in IP6 can
 299     cause netifd to execute procd interface reload. Limit Unbound procd
 300     triggers to LAN and WAN (IP4 only) to prevent restart @2-3 minutes.
 301 ```
 302
 303