A commandline tool to check forward and reverse DNS for a CSV of hostnames or IP addresses
Usage: roundtrip [--out=out.csv] [file.csv]
--column string Look for addresses or hostnames in this column (default "1")
--discards string Write bad input lines to this csv file
-h, --help Print this help and exit
-o, --out string Send output CSV to this file
--version Print version information and exit
roundtrip takes a single CSV file on the commandline. The first line of that CSV file should contain column names.
By default it expects the first column to contain an IP address or a hostnames. You can pass a column name or number
with the --column flag to use another column for input. roundtrip will check forward and reverse
DNS for each record, and add three new columns to the end of each line of the CSV.
The first added column contains the IP addresses it resolved from hostnames, while the second contains the hostnames it resolved from IP addresses. The third added column contains "yes" if there is valid roundtrip / FCrDNS for the row.
If there are any input rows that can't be parsed as hostnames or IP addresses they will be discarded, or written to the file given by the --discards flag.
Binary releases of roundtrip are available under Releases.
You'll need to unpack them with tar zxf roundtrip-<stuff>.tar.gz or unzip the Windows packages.
These are built automatically and right now the workflow doesn't sign the binaries. You'll need to bypass
the check for that, e.g. on macOS open it in finder, right click on it and select Open then give permission
for it to run.
It's also a regular Go application, so you can clone the source and run go build to build it yourself.
This is a fairly quick hack for my own use rather than production grade code. Patches or pull requests welcome.