checkip

Sometimes I come across an IP address, reviewing logs for example, and I want to know more about this numerical label. Checkip is CLI tool and Go library that provides (security) information on IP addresses. It runs various checks to get the information. Most checks are passive, i.e. not interacting directly with the IP address. Active checks, like ping and tls, are not aggressive.

Quick start

$ go install github.com/jreisinger/checkip@latest
$ checkip 1.1.1.1 91.228.166.47
--- 1.1.1.1 ---
db-ip.com       Sydney, Australia
dns name        one.one.one.one
iptoasn.com     CLOUDFLARENET
is on AWS       false
isc.sans.edu    attacks: 0, abuse contact: abuse@cloudflare.com
ping            0% packet loss (5/5), avg round-trip 4 ms
tls             TLS 1.3, exp. 2026/01/21, cloudflare-dns.com, *.cloudflare-dns.com, one.one.one.one
virustotal.com  network: 1.1.1.0/24, SAN: cloudflare-dns.com, *.cloudflare-dns.com, one.one.one.one, 1.0.0.1, 1.1.1.1, 162.159.36.1, 162.159.46.1, 2606:4700:4700::1001, 2606:4700:4700::1111, 2606:4700:4700::64, 2606:4700:4700::6400
malicious prob. 0% (0/12) ✅
--- 91.228.166.47 ---
db-ip.com       Petržalka, Slovakia
dns name        skh1-webredir01-v.eset.com
iptoasn.com     ESET-AS
is on AWS       false
isc.sans.edu    attacks: 0, abuse contact: domains@eset.sk
ping            0% packet loss (5/5), avg round-trip 5 ms
tls             TLS 1.3, exp. 2024/01/02!!, www.eset.com, eset.com
virustotal.com  network: 91.228.164.0/22, SAN: www.eset.com, eset.com
malicious prob. 17% (2/12) 🤏

More usage examples

Use detailed JSON output to filter out those checks that consider the IP address to be malicious:

checkip -j 91.228.166.47 | jq '.checks[] | select(.ipAddrIsMalicious == true)'

Check multiple IP addresses coming from STDIN:

dig +short eset.sk | checkip

Continuously generate random IP addresses and check them (hit Ctrl-C to stop):

while true; do ./randip; sleep 2; done | checkip 2> /dev/null

Generate 100 random IP addresses and select Russian or Chinese:

./randip 100 | checkip -p 20 -j 2> /dev/null | \
jq -r '.ipAddr as $ip | .checks[] | select (.description == "db-ip.com" and (.ipAddrInfo.iso_code == "RU" or .ipAddrInfo.iso_code == "CN")) | $ip'

Find out who is trying to SSH into your Linux system:

sudo journalctl --unit ssh --since "1 hour ago" | \
grep 'Bye Bye' | perl -wlne '/from ([\d\.]+)/ && print $1' | sort | uniq | \
checkip 2> /dev/null

Installation

To install the CLI tool

# optional; to install inside a container
docker run --rm -it golang /bin/bash

go install github.com/jreisinger/checkip@latest

or download a release binary (from under "Assets") for your system and architecture.

Configuration and cache

For some checks to start working you need to sign up on a web site (like https://www.abuseipdb.com) and get an API (or LICENSE) key. Checkip doesn't report an absent API key as an error; the check is simply not executed and missingCredentials JSON field is set to the name of the API key (like ABUSEIPDB_API_KEY).

Store the keys in $HOME/.checkip.yaml file:

ABUSEIPDB_API_KEY: aaaaaaaabbbbbbbbccccccccddddddddeeeeeeeeffffffff11111111222222223333333344444444
MAXMIND_LICENSE_KEY: abcdef1234567890
SHODAN_API_KEY: aaaabbbbccccddddeeeeffff11112222
URLSCAN_API_KEY: abcd1234-a123-4567-678z-a2b3c4b5d6e7
VIRUSTOTAL_API_KEY: aaaaaaaabbbbbbbbccccccccddddddddeeeeeeeeffffffff1111111122222222

You can also use environment variables with the same names.

Data used by some checks is downloaded (cached) to $HOME/.checkip/ folder. Is gets periodically re-downloaded so it is fresh.

Development

Checkip is easy to extend. If you want to add a new way of checking IP addresses:

1. Write a function of type check.Func.
2. Add it to check.Funcs variable.

Typical workflow:

make run # test and run

git commit

git tag | sort -V | tail -1
git tag -a v0.2.0 -m "new check func"

git push --follow-tags # will build a new release on GitHub