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Simple tools for keeping the SPF TXT records tidy in order to fight 10 maximum DNS lookups.
Your original TXT record which causes more than 10 DNS lookups
should be saved as an otherwise unused subdomain TXT record
(e.g. orig.spf-tools.ml).
Create a configuration file:
cat > ~/.spf-toolsrc <<EOF
DOMAIN=spf-tools.ml
ORIG_SPF=orig.spf-tools.ml
DNS_TIMEOUT=5
EOF
Now just call any of the scripts described below.
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 dig +time=SECS command.
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 and EMAIL variable definitions which are 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.ml) and original SPF record with includes
(e.g. orig.spf-tools.ml) in order to use runspftools.sh
without modifying the script.
Usage:
./despf.sh | ./normalize.sh | ./simplify.sh | ./mkblocks.sh \
> /tmp/out 2>&1
grep "Too many DNS lookups!" /tmp/out \
|| cat /tmp/out | ./mkzoneent.sh | ./cloudflare.sh
./despf.sh | ./normalize.sh | ./simplify.sh \
| ./mkblocks.sh | ./xsel.sh
- https://dmarcian.com/spf-survey/spf-tools.ml
- https://dmarcian.com/spf-survey/orig.spf-tools.ml
- 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
Copyright 2015 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.