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Simple tools for keeping the SPF TXT records tidy in order to fight 10 maximum DNS look-ups.
Domain name spf-tools.eu.org is used for testing now.
spf-tools since version spf-tools/spf-tools@f4f51f7 do not
output merely ip4 and ip6 records, but also keep original ptr
and exists ones.
Your original TXT record which causes more than 10 DNS look-ups
should be saved as an otherwise unused subdomain TXT record
(e.g. spf-orig.spf-tools.eu.org).
Create a configuration file:
cat > ~/.spf-toolsrc <<EOF
DOMAIN=spf-tools.eu.org
ORIG_SPF=spf-orig.spf-tools.eu.org
DESPF_SKIP_DOMAINS=_spf.domain1.com:spf.domain2.org
DNS_TIMEOUT=5
DNS_SERVER=
EOF
Now just call any of the scripts described below.
Usage: despf.sh [OPTION]... [DOMAIN]...
Decompose SPF records of a DOMAIN. Optionaly can
sort and unique them.
DOMAIN may be specified in an environment variable.
Available options:
-s DOMAIN[:DOMAIN...] skip domains, i.e. leave include
without decomposition
-t N set DNS timeout to N seconds
-h display this help and exit
despf.sh is a tool that resolves all ip4 and ip6 blocks
found in any included SPF subdomain. It prints all these blocks
sort(1)ed and uniq(1)ed to stdout, one per line.
Other output (Getting ...) is on stderr.
Example:
./despf.sh google.com
Getting _spf.google.com
Getting _netblocks.google.com
Getting _netblocks2.google.com
Getting _netblocks3.google.com
ip4:173.194.0.0/16
ip4:74.125.0.0/16
...
ip6:2a00:1450:4000::/36
ip6:2c0f:fb50:4000::/36
The DNS_TIMEOUT configuration variable sets number of seconds
for the host -W SECS command (the same as option -t, see
help).
mkblocks.sh tool is meant to parse a list of blocks produced by
despf.sh and prepare content of TXT records that all fit into one
UDP packet, splitting into more TXT records if needed.
One TXT record per line of standard output.
./despf.sh | ./normalize.sh | ./simplify.sh | ./mkblocks.sh
Current SPF records can be verified by running compare.sh.
If the TXT records need an update, it will automatically run
the other tools to print out or copy into pastebuffer the
new TXT records in reverse order.
Best practice is to put those lines into DNS starting with the
last one. That's why xsel.sh reverses the input gathered from
mkblocks.sh.
The last record to update is root domain's record which just
contains an include. It should be always updated as the last one
and the prefix alternated between spf and _spf prefixes when
changing records, so the records are all consistent until the
root one is changed.
In order to semi-automate the task of updating the records,
pipe the output of mkblocks.sh to xsel.sh.
This script takes care of correct CIDR ranges. At the moment only IPv4.
Example:
$ ./normalize.sh <<EOF
> ip4:207.68.169.173/30
> ip4:207.68.169.175/30
> ip4:65.55.238.129/26
> EOF
ip4:207.68.169.172/30
ip4:207.68.169.172/30
ip4:65.55.238.128/26
This script takes out individual IPv4 addresses which are already contained in CIDR ranges.
$ ./simplify.sh <<EOF
> ip4:192.168.0.1
> ip4:192.168.0.0/24
> EOF
ip4:192.168.0.0/24
Dependencies: jq, awk, sed, grep
Script to update pre-existing TXT SPF records for a domain according to the input in DNS zone format using CloudFlare's API.
To use this script, file .spf-toolsrc in $HOME directory should
contain TOKEN variable definition which is then used
to connect to CloudFlare API. The file should also contain DOMAIN
and ORIG_SPF variables which stand for the target SPF domain
(e.g. spf-tools.eu.org) and original SPF record with includes
(e.g. spf-orig.spf-tools.eu.org) in order to use runspftools.sh
without modifying the script.
The script is written against v4 of https://api.cloudflare.com/
The only needed permissions for a custom API token are:
- Zone.Zone: Read
- Zone.DNS: Edit
Usage:
./despf.sh | ./normalize.sh | ./simplify.sh | ./iprange.sh | ./cloudflare.sh
Dependencies: jq, aws, awk, sed, grep
Usage: route53.sh [OPTION]... [HOSTED_ZONE_ID]
Script to update pre-existing TXT SPF records for
a domain according to the input in DNS zone format.
Available options:
-t TTL set Time To Live for DNS records
-a TXT RECORD set aditional TXT record to domain (can be used multiple times)
Default values:
TTL = 300
Script to update pre-existing TXT SPF records for a domain according to the input in DNS zone format.
The AWS CLI can be configured using ~/.aws/credentials or using
environment variables: AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
(find more details in Configuring the AWS CLI
documentation.
Example:
./despf.sh | ./simplify.sh | ./mkblocks.sh | \
./route53.sh -a "google-site-verification=deadbeef" DEADBEEF
Extra dependencies: iprange
This script optimizes the IPv4 address block output (similar to, but
more than simplify.sh because it can join multiple networks into
one bigger).
Usage:
./despf.sh | ./iprange.sh
Example:
$ ./despf.sh cont.spf-tools.eu.org
ip4:13.111.0.0/24
ip4:13.111.1.0/24
ip4:13.111.2.0/24
ip4:13.111.3.0/24
$ ./despf.sh cont.spf-tools.eu.org | ./iprange.sh
ip4:13.111.0.0/22
./despf.sh | ./normalize.sh | ./simplify.sh | ./iprange.sh \
| ./mkblocks.sh | ./xsel.sh
As we are successfully using a free eu.org domain, we are proud to spread the word: Free domains: http://www.eu.org/
- https://dmarcian.com/spf-survey/spf.spf-tools.eu.org
- https://dmarcian.com/spf-survey/spf-orig.spf-tools.eu.org
- http://www.kitterman.com/spf/validate.html
- http://serverfault.com/questions/584708
- http://www.openspf.org/SPF_Record_Syntax
- http://tools.ietf.org/html/rfc7208#section-5.5
- http://tools.ietf.org/html/rfc7208#section-14.1
- https://space.dmarcian.com/too-many-dns-lookups/
- https://nic.eu.org/
Copyright 2015-2019 spf-tools team (see AUTHORS)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.