Can fail2ban-client tell me if an ip from a CIDR range is in a jail?

jaygooby

2/21/23, 9:22 AM

If I have a CIDR like 13.54.63.128/26 can fail2ban-client tell me if there's an IP in this range that's currently banned?

Currently I'm doing:

CIDR="13.54.63.128/26"
nmap -sL -n $CIDR | awk '/Nmap scan report/{print $NF}' | while read ip
do
  sudo iptables -L -n | grep $ip
done

which does the job, but feels a bit hacky.

Please note this is not a question concerning fail2ban's partial IP matching. I want to know the client's ability to report on banned IPs.

105

0 + 0

cidr

fail2ban

djdomi

2/21/23, 3:18 PM

Does this answer your question? [Fail2ban partial IP match possible?](https://serverfault.com/questions/1080041/fail2ban-partial-ip-match-possible) - currently, fail2ban does not have Subnet support, its planned for the future

Nikita Kipriyanov

3/27/23, 11:33 AM

I feel the ability of `fail2ban-client` to tell if some IP from a given range is banned is *also* the ability of *fail2ban* (as a product) to do a partical IP matching. Not for adding a range into ban instead of single IP; the matching is going to be peformed for other use case, but the "duplicate" answer still fully applies.

Score:3

Server

Johhnie

2/21/23, 2:27 PM

There is a nifty little tool grepcidr that is useful for quick shell scripts that need to find matches from a specific CIDR in a list with IPv4 or IPv6 addresses.

 sudo iptables -L -n | grepcidr  "13.54.63.128/26"

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Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Can fail2ban-client tell me if an ip from a CIDR range is in a jail?

TH: ลูกค้า fail2ban สามารถบอกฉันได้ไหมว่า ip จากช่วง CIDR อยู่ในคุกหรือไม่

RO: Poate fail2ban-client să-mi spună dacă un ip dintr-un interval CIDR este într-o închisoare?

RU: Может ли fail2ban-client сказать мне, находится ли IP-адрес из диапазона CIDR в тюрьме?

VI: fail2ban-client có thể cho tôi biết nếu một ip từ phạm vi CIDR đang ở trong tù không?

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