Remote managing a server is important but I believe securing it is just as important.
Would you like to type “last” and just relize someone has just login into your server from a far country?
Well the solution is here!
We will be installing fail2ban, witch is capable of monitoring not just SSH but many other daemons.
Check out my other posts related to this:
It is quite cool, it send you an email after X attempts and include that bad IP into iptables for X amount of time.
Installing in Debian:
# apt-get install fail2ban
Installing in RedHat,CentOS,Fedora:
tar -xjvf fail2ban-0.9.4.tar.gz
python setup.py install
Autostart in RedHat,CentOS,Fedora
cp files/redhat-initd /etc/init.d/fail2ban
chkconfig –add fail2ban
chkconfig fail2ban on
service fail2ban start
Fail2ban is automatically configured for the most part. However, little items need to be tweaked.
/etc/fail2ban/fail2ban.conf is responsible for general settings for fail2ban, such as what log to append to. More specific settings can be changed in /etc/fail2ban/jail.conf. However, it’s recommended that this file not be directly changed. Instead, make a copy to jail.local. The local file with override the .conf one.
# cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local
First, under [DEFAULT] find ignoreip. It’s always important for you to have a way in! These are IPs are fail2ban will ignore – IPs listed here can always have invalid login. These need to be space separated.
Check also the bantime, maxrety and other settings. I believe the bantime of only 10min ( 600 sec) is not enough to handle an attack,
so I raised it to 86400 (24 hours).Also adjust the logfiles path and names to your system.
# “ignoreip” can be an IP address, a CIDR mask or a DNS host
ignoreip = 127.0.0.1 172.31.0.0/24 10.10.0.0/24 192.168.0.0/24
bantime = 86400
maxretry = 5
enabled = true
filter = sshd
action = iptables[name=SSH, port=ssh, protocol=tcp]
sendmail-whois[name=SSH, email@example.com, firstname.lastname@example.org]
logpath = /var/log/auth.log
maxretry = 5
logpath=/var/log/secure (for RedHat,CentOS,Fedora)
Then restart the service:
# /etc/init.d/fail2ban restart
# service fail2ban restart
And check your iptables:
# iptables -L
If you want to unblock someone just do:
# iptables -D fail2ban-ssh 1
Show failed SSH logins by date:
# cat /var/log/secure | grep ‘Failed password’ | sort | uniq -c
There is also a cool nagios plugin
More on Fail2Ban
Appendix, Install email server: smail, sendmail:
#apt-get install smail
1.) stop the Service
2.) delete the socket if avalible
3.) start the Service
4.) check if fail2ban is working
Answer should be “pong”
5.) if the answer is not “pong” run away or CRY FOR HELP 😉
13 thoughts on “Secure SSH with Fail2Ban”
Hey there, wanted to thank you for your script, it helped me to finetune my fail2ban, thanks
It works !
Afther lots of reading and your blog I finaly got.
thanks alot 🙂
You could replace this horrible ‘useless use of cat’ (see uuoc.com) with :
grep ‘Failed password’ /var/log/secure| sort -u |wc -l
I followed the instructions for CentOS/RHEL, and I cannot get it to ban ssh attempts from another box, even though I copied your instructions.
Check the logging directive in your sshd configuration file. I had the same trouble on a CentOS 5.5 host until I realized that ssh is logging to syslog on AUTHPRIV, which puts everything in ‘/var/log/secure’.
Just change the log line in ‘jail.local’ or ‘jail.conf’ to read:
logpath = /var/log/secure
Make sure that iptables is running, restart fail2ban, and you’re in business.
really great post, thanks for that. came across some real problems getting yum to do the install so this method really saved the day.
Thanks for posting this! It’s been very helpful for setting up my tunneling server.
Killing brute-forcer kiddies made easy. ..
Thank you SO much for the easy-to-follow, concise instructions.
In case it helps anyone else using Fedora — the command to unban on mine was
iptables -D fail2ban-SSH 1
Note the capitalized SSH. I installed from package via yum install fail2ban, maybe that’s part of it.
Many thanks for this. By the way, for Fail2ban version 0.8.12 you need a whois program. I did this to get one:
yum install jwhois
Thank you very much. This excerpt made the manual of fail2ban very clear.