checkip

Sometimes I come across an IP address, for example when reviewing logs. And I’d like to find out more about this numerical label. Checkip is CLI tool and Go library that provides information on and security posture of IP addresses. Most checks are passive. Active checks (like ping and tls) are not aggressive.

Quick start

go install github.com/jreisinger/checkip@latest
checkip 1.1.1.1

Usage examples

Check an IP address:

❯ checkip 91.228.166.47
--- 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            100% packet loss (5/0), avg round-trip 0 ms
tls             TLS 1.3, exp. 2024/01/02!!, www.eset.com, eset.com
malicious prob. 8% (1/12) ✅

Check multiple IP addresses coming from STDIN:

❯ dig +short eset.sk | checkip
--- 91.228.167.128 ---
db-ip.com       Petržalka, Slovakia
dns name        h3-webredir02-v.eset.com
iptoasn.com     ESET-AS
is on AWS       false
isc.sans.edu    attacks: 0, abuse contact: domains@eset.sk
ping            100% packet loss (5/0), avg round-trip 0 ms
tls             TLS 1.3, exp. 2024/01/02!!, www.eset.com, eset.com
malicious prob. 9% (1/11) ✅
--- 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            100% packet loss (5/0), avg round-trip 0 ms
tls             TLS 1.3, exp. 2024/01/02!!, www.eset.com, eset.com
malicious prob. 8% (1/12) ✅

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)'
{
  "description": "tls",
  "type": "InfoAndIsMalicious",
  "ipAddrIsMalicious": true,
  "ipAddrInfo": {
    "SAN": [
      "www.eset.com",
      "eset.com"
    ],
    "Version": 772,
    "Expiry": "2024-01-02T23:59:59Z"
  }
}

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

❯ while true; do ./randip; sleep 2; done | checkip 2> /dev/null
--- 155.186.85.125 ---
db-ip.com       Ashburn, United States
dns name        syn-155-186-085-125.res.spectrum.com
iptoasn.com     CHARTER-20115
is on AWS       false
isc.sans.edu    attacks: 0, abuse contact: abuse@charter.net
ping            100% packet loss (5/0), avg round-trip 0 ms
malicious prob. 0% (0/10) ✅
--- 115.159.53.216 ---
db-ip.com       Shenzhen (Futian Qu), China
iptoasn.com     TENCENT-NET-AP Shenzhen Tencent Computer Systems Company Limited
is on AWS       false
isc.sans.edu    attacks: 0, abuse contact: ipas@cnnic.cn
ping            100% packet loss (5/0), avg round-trip 0 ms
malicious prob. 0% (0/10) ✅

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'
19.226.129
32.13.38
210.45.205

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
--- 167.172.105.64 ---
db-ip.com       Frankfurt am Main, Germany
iptoasn.com     DIGITALOCEAN-ASN
ping            0% packet loss (5/5), avg round-trip 21 ms
tls             TLS 1.3, exp. 2024/12/27, portal.itruck.com.sa, www.portal.itruck.com.sa
malicious prob. 43% (3/7) 🤏
--- 180.168.95.234 ---
db-ip.com       Shanghai, China
iptoasn.com     CHINANET-SH-AP China Telecom Group
ping            0% packet loss (5/5), avg round-trip 213 ms
malicious prob. 50% (3/6) 🚫

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

For some checks to start working you need to register and get an API (LICENSE) key. See the service web site for how to do that. An absent key is not reported as an error, the check is simply not executed and missingCredentials JSON field is set.

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 are downloaded (cached) to $HOME/.checkip/ folder. They are periodically re-downloaded so they are fresh.

Development

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

Write a function of type check.Func.
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

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