The recursor
resolves domains using defined IP addresses or resolving other mapped domains using defined resolvers.
The recursor
definition:
zone
- DNS zone for the recursorverbose
- stdout logs level:0
- minimal1
- middle2
- talkative
resolvers
- other DNS servers:- map-key/id: name of resolver,
default
overrides system default resolver urls
: list of URL addresses, example:udp://127.0.0.1:53
(system default is represented by://default
)timeout_ms
: resolver connection timeout in millisecods
- map-key/id: name of resolver,
aliases
- domain aliases:- map-key/id: name of alias, subdomain or
*
if you want the recursor to be a DNS repeater ips
: IP addresses to return as a part of answerhosts
: domains to be resolved so that the IP addresses obtained in this way will be returned as a part of answerresolver_name
: the defined resolver reference, default is...default
of course :)ttl
: DNS record Time To Live in seconds
- map-key/id: name of alias, subdomain or
recursor {
[external-yaml config-file-path]
[external-json config-file-path]
[verbose 0..2]
zone: demo.svc
resolver dns-c {
urls udp://1.1.1.1:53 udp://1.0.0.1:53
timeout_ms 500
}
resolver dns-g {
urls udp://8.8.8.8:53 udp://8.8.4.4:53
}
resolver demo {
urls udp://10.0.0.1:53
}
alias alias1 {
hosts www.example.org www.example.com
resolver_name dns-c
ttl 11
}
alias alias2 {
ips 10.0.0.1 10.0.0.2
ttl 12
}
alias alias3 {
ips 10.0.0.1 10.0.0.2
hosts www.example.net
resolver_name dns-g
ttl 13
}
alias alias4 {
hosts www.example.net
ttl 14
}
alias * {
resolver_name demo
ttl 15
}
}
zone: demo.svc
resolvers:
dns-c:
urls: [ udp://1.1.1.1:53, udp://1.0.0.1:53 ]
timeout_ms: 500
dns-g:
urls: [ udp://8.8.8.8:53, udp://8.8.4.4:53 ]
demo:
urls: [ udp://10.0.0.1:53 ]
aliases:
alias1:
hosts: [ www.example.org, www.example.com ]
resolver_name: dns-c
ttl: 11
alias2:
ips: [ 10.0.0.1, 10.0.0.2 ]
ttl: 12
alias3:
ips: [ 10.0.0.1, 10.0.0.2 ]
hosts: [ www.example.net ]
resolver_name: dns-g
ttl: 13
alias4:
hosts: [ www.example.net ]
ttl: 14
"*":
resolver_name: demo
ttl: 15
{
"zone": "demo.svc",
"resolvers": {
"dns-c": {
"urls": [ "udp://1.1.1.1:53", "udp://1.0.0.1:53" ],
"timeout_ms": 500
},
"dns-g": {
"urls": [ "udp://8.8.8.8:53", "udp://8.8.4.4:53" ]
},
"demo": {
"urls": [ "udp://10.0.0.1:53" ]
}
},
"aliases": {
"alias1": {
"hosts": [ "www.example.org", "www.example.com" ],
"resolver_name": "dns-c",
"ttl": 11
},
"alias2": {
"ips": [ "10.0.0.1", "10.0.0.2" ],
"ttl": 12
},
"alias3": {
"ips": [ "10.0.0.1", "10.0.0.2" ],
"hosts": [ "www.example.net" ],
"resolver_name": "dns-g",
"ttl": 13
},
"alias4": {
"hosts": [ "www.example.net" ],
"ttl": 14
},
"*": {
"resolver_name": "demo",
"ttl": 15
}
}
}
#!/usr/bin/env bash
set -eux
# Extract coredns source code
tar xzvf coredns.src.tar.gz
pushd coredns
# Add external plugins
go get github.com/kinjelom/coredns-recursor@latest
echo -e "recursor:github.com/kinjelom/coredns-recursor" >> plugin.cfg
# Build
go generate
go build
./coredns -plugins
popd
Helpful commands:
dig alias1.demo.svc @127.0.0.1 -p 1053
nslookup -port=1053 -debug -type=A alias2.demo.svc 127.0.0.1