Tutorial
How To Protect SSH with Fail2Ban on Ubuntu 14.04
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Introduction
While connecting to your server through SSH can be very secure, the SSH daemon itself is a service that must be exposed to the internet to function properly. This comes with some inherent risk and creates a vector of attack for would-be assailants.
Any service that is exposed to the network is a potential target in this way. If you pay attention to application logs for these services, you will often see repeated, systematic login attempts that represent brute force attacks by users and bots alike.
A service called fail2ban can mitigate this problem by creating rules that can automatically alter your iptables firewall configuration based on a predefined number of unsuccessful login attempts. This will allow your server to respond to illegitimate access attempts without intervention from you.
In this guide, we’ll cover how to install and use fail2ban on an Ubuntu 14.04 server.
Install Fail2Ban on Ubuntu 14.04
The installation process for this tool is simple because the Ubuntu packaging team maintains a package in the default repositories.
First, we need to update our local package index and then we can use apt to download and install the package:
As you can see, the installation is trivial. We can now begin configuring the utility for our own use.
Configure Fail2Ban with your Service Settings
The fail2ban service keeps its configuration files in the /etc/fail2ban directory. There is a file with defaults called jail.conf.
Since this file can be modified by package upgrades, we should not edit this file in-place, but rather copy it so that we can make our changes safely. In order for these two files to operate together successfully, it is best to only include the settings you wish to override in the jail.local file. All default options will be taken from the jail.conf file.
Even though we should only include deviations from the default in the jail.local file, it is easier to create a jail.local file based on the existing jail.conf file. So we will copy over that file, with the contents commented out, as the basis for the jail.local file. You can do this by typing:
Once the file is copied, we can open the original jail.conf file to see how things are set up by default
In this file, there are a few settings you may wish to adjust. The settings located under the [DEFAULT] section will be applied to all services enabled for fail2ban that are not overridden in the service’s own section.
[DEFAULT]
. . .
ignoreip = 127.0.0.1/8
. . .
The ignoreip setting configures the source addresses that fail2ban ignores. By default, it is configured to not ban any traffic coming from the local machine. You could add additional addresses to ignore by adding a [DEFAULT] section with an ignoreip setting under it to the jail.local file. You can add additional addresses by appending them to the end of the directive, separated by a space.
[DEFAULT]
. . .
bantime = 600
. . .
The bantime parameter sets length of time that a client will be banned when they have failed to authenticate correctly. This is measured in seconds. By default, this is set to 600 seconds, or 10 minutes.
[DEFAULT]
. . .
findtime = 600
maxretry = 3
. . .
The next two parameters that you want to pay attention to are findtime and maxretry. These work together to establish the conditions under which a client is found to be an illegitimate user that should be banned.
The maxretry variable sets the number of tries a client has to authenticate within a window of time defined by findtime, before being banned. With the default settings, the fail2ban service will ban a client that unsuccessfully attempts to log in 3 times within a 10 minute window.
[DEFAULT]
. . .
destemail = root@localhost
sendername = Fail2Ban
mta = sendmail
. . .
You will want to evaluate the destemail, sendername, and mta settings if you wish to configure email alerts. The destemail parameter sets the email address that should receive ban messages. The sendername sets the value of the “From” field in the email. The mta parameter configures what mail service will be used to send mail. Again, add these to the jail.local file, under the [DEFAULT] header and set to the proper values if you wish to adjust them.
[DEFAULT]
. . .
action = $(action_)s
. . .
This parameter configures the action that fail2ban takes when it wants to institute a ban. The value action_ is defined in the file shortly before this parameter. The default action is to simply configure the firewall to reject traffic from the offending host until the ban time elapses.
If you would like to configure email alerts, add or uncomment the action item to the jail.local file and change its value from action_ to action_mw. If you want the email to include the relevant log lines, you can change it to action_mwl. Make sure you have the appropriate mail settings configured if you choose to use mail alerts.
Individual Jail Settings
Finally, we get to the portion of the configuration file that deals with individual services. These are specified by the section headers, like [ssh].
Each of these sections can be enabled by uncommenting the header in jail.local and changing the enabled line to be “true”:
[jail_to_enable]
. . .
enabled = true
. . .
By default, the SSH service is enabled and all others are disabled.
These sections work by using the values set in the [DEFAULT] section as a basis and modifying them as needed. If you want to override any values, you can do so by adding the appropriate service’s section to jail.local and modifying its values.
Some other settings that are set here are the filter that will be used to decide whether a line in a log indicates a failed authentication and the logpath which tells fail2ban where the logs for that particular service are located.
The filter value is actually a reference to a file located in the /etc/fail2ban/filter.d directory, with its .conf extension removed. These files contain the regular expressions that determine whether a line in the log is a failed authentication attempt. We won’t be covering these files in-depth in this guide, because they are fairly complex and the predefined settings match appropriate lines well.
However, you can see what kind of filters are available by looking into that directory:
If you see a file that looks to be related to a service you are using, you should open it with a text editor. Most of the files are fairly well commented and you should be able to at least tell what type of condition the script was designed to guard against. Most of these filters have appropriate (disabled) sections in the jail.conf file that we can enable in the jail.local file if desired.
For instance, pretend that we are serving a website using Nginx and realize that a password-protected portion of our site is getting slammed with login attempts. We can tell fail2ban to use the nginx-http-auth.conf file to check for this condition within the /var/log/nginx/error.log file.
This is actually already set up in a section called [nginx-http-auth] in our /etc/fail2ban/jail.conf file. We would just need to uncomment the section in the jail.local file and flip the enabled parameter to protect our service:
. . .
[nginx-http-auth]
enabled = true
. . .
If you enable this, you’ll want to restart your fail2ban service to make sure your rules are constructed correctly.
Putting It All Together
Now that you understand the basic idea behind fail2ban, let’s run through a basic setup.
We’re going to configure a auto-banning policy for SSH and Nginx, just as we described above. We want fail2ban to email us when an IP is banned.
First, let’s install all of the relevant software.
If you don’t already have it, you’ll need nginx, since we’re going to be monitoring its logs, and you’ll need sendmail to mail us notifications. We’ll also grab iptables-persistent to allow the server to automatically set up our firewall rules at boot. These can be acquired from Ubuntu’s default repositories:
Stop the fail2ban service for a moment so that we can establish a base firewall without the rules it adds:
Establish a Base Firewall
When that is finished, we should implement a default firewall. You can learn how to configure an iptables firewall on Ubuntu 14.04 here. We are going to just create a basic firewall for this guide.
We’re going to tell it to allow established connections, traffic generated by the server itself, traffic destined for our SSH and web server ports. We will drop all other traffic. We can set this basic firewall up by typing:
These commands will implement the above policy. We can see our current firewall rules by typing:
Output-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -j DROP
You can save the firewalls so that they survive a reboot by typing:
Afterwards, you can restart fail2ban to implement the wrapping rules:
We can see our current firewall rules by typing:
Output-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N fail2ban-ssh
-A INPUT -p tcp -m multiport --dports 22 -j fail2ban-ssh
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -j DROP
-A fail2ban-ssh -j RETURN
We have our default policy for each of our chains, and then the five base rules that we established. In red, we also have the default structure set up by fail2ban since it already implements SSH banning policies by default. These may or may not show up at first, since sometimes fail2ban does not add the structure until the first ban is implemented.
Adjusting the Fail2ban Configuration
Now, we need to configure fail2ban using the settings we’d like. Open the jail.local file:
We can set a more severe ban time here. Find and uncomment the [DEFAULT] heading. Under the default heading, change the bantime setting so that our service bans clients for half an hour:
[DEFAULT]
. . .
bantime = 1800
. . .
We also need to configure our alert email information. First, find the destemail parameter, which should also be under the [DEFAULT] heading. Put in the email address that you want to use to collect these messages:
[DEFAULT]
. . .
destemail = admin@example.com
. . .
You can set the sendername to something else if you’d like. It’s useful to have a value that can be easily filtered using your mail service though, or else your regular inbox may get flooded with alerts if there are a lot of break in attempts from various places.
Moving down, we need to adjust the action parameter to one of the actions that sends us email. The choices are between action_mw which institutes the ban and then emails us a “whois” report on the offending host, or action_mwl which does the above, but also emails the relevant log lines.
We’re going to choose action_mwl because the log lines will help us troubleshoot and gather more information if there are issues:
[DEFAULT]
. . .
action = %(action_mwl)s
. . .
Moving on to our SSH section, if we want to adjust the amount of unsuccessful attempts that should be allowed before a ban is established, you can edit the maxretry entry. If you are using a port other than “22”, you’ll want to adjust the port parameter appropriately. As we said before, this service is already enabled, so we don’t need to modify that.
Next, search for the nginx-http-auth section. Uncomment the header and change the enabled parameter to read “true”.
. . .
[nginx-http-auth]
enabled = true
. . .
This should be all you have to do this section unless your web server is operating on non-standard ports or if you moved the default error log path.
Restarting the Fail2ban Service
When you are finished, save and close the file.
Now, start or restart your fail2ban service. Sometimes, it’s better to completely shut down the service and then start it again:
Now we can restart it by typing:
It may take a few moments for all of your firewall rules to be populated. Sometimes, the rules are not added until the first ban of that type is instituted. However, after a time, you can check the new rules by typing:
Output-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N fail2ban-nginx-http-auth
-N fail2ban-ssh
-A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-nginx-http-auth
-A INPUT -p tcp -m multiport --dports 22 -j fail2ban-ssh
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -j DROP
-A fail2ban-nginx-http-auth -j RETURN
-A fail2ban-ssh -j RETURN
The lines in red are the ones that our fail2ban policies have created. Right now, they are just directing traffic to new, almost empty chains and then letting the traffic flow right back into the INPUT chain.
However, these new chains are where the banning rules will be added.
Testing the Banning Policies
From another server, one that won’t need to log into your fail2ban server with, we can test the rules by getting our second server banned.
After logging into your second server, try to SSH into the fail2ban server. You can try to connect using a non-existent name for instance:
Enter random characters into the password prompt. Repeat this a few times. At some point, the fail2ban server will stop responding with the Permission denied message. This signals that your second server has been banned from the fail2ban server.
On your fail2ban server, you can see the new rule by checking our iptables again:
Output-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N fail2ban-nginx-http-auth
-N fail2ban-ssh
-A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-nginx-http-auth
-A INPUT -p tcp -m multiport --dports 22 -j fail2ban-ssh
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -j DROP
-A fail2ban-nginx-http-auth -j RETURN
-A fail2ban-ssh -s 203.0.113.14/32 -j REJECT --reject-with icmp-port-unreachable
-A fail2ban-ssh -j RETURN
As you can see in the highlighted line, we have a new rule in our configuration which rejects traffic to the SSH port coming from our second server’s IP address. You should have also gotten an email about the ban in the account you configured.
Conclusion
You should now be able to configure some basic banning policies for your services. Fail2ban is very easy to set up, and is a great way to protect any kind of service that uses authentication.
If you want to learn more about how fail2ban works, you can check out our tutorial on how fail2ban rules and files work.
For information about how to use fail2ban to protect other services, try these links:
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I’ve been considering fail2ban but am unsure if I really need it. I have disabled password login and setup my iptable rules which are below:
-P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -d 127.0.0.0/8 ! -i lo -j DROP -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT -A INPUT -j DROP -A FORWARD -j DROP -A OUTPUT -j ACCEPT
I installed fail2ban, and after it inserted its rules, my iptables now look like this:
-P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT -N fail2ban-nginx-http-auth -N fail2ban-ssh -A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-nginx-http-auth -A INPUT -p tcp -m multiport --dports 22 -j fail2ban-ssh -A INPUT -i lo -j ACCEPT -A INPUT -d 127.0.0.0/8 ! -i lo -j DROP -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT -A INPUT -j DROP -A FORWARD -j DROP -A OUTPUT -j ACCEPT -A fail2ban-nginx-http-auth -j RETURN -A fail2ban-ssh -j RETURN
I’m guessing there is some redundancy/overkill now. Thoughts?
Hi brandon:
Looking at your configuration, I would say that fail2ban is still going to be useful for you. Your first configuration that you posted above drops connection attempts that are not directed to port 80, 443, or 22 (as well as allowing local connections).
However, the point of fail2ban is to ban people who repeatedly fail to authenticate. This means that if someone is attempting to log into SSH, they will be banned after a few attempts, causing them to move on. This rule would be added to the
fail2ban-sshchain prior to the-A fail2ban-ssh -j RETURNrule.While this might not seem like a big deal considering that you have already disabled password logins through the sshd config file, it will help keep your logs clean. This can be incredibly useful when you are trying to analyze your logs in case of a problem by cutting down on the background noise.
Also, with the Nginx, the Auth_Basic module that provides authentication doesn’t have the functionality to limit attempts. If you have sections of your site protected by password authentication, you probably will benefit from a service like fail2ban limiting the number of authentication attempts.
In general though, this is up to you and if you feel that fail2ban is not providing value, you do not have to use it. However, in my testing, it doesn’t use many resources, so it may be worth it to keep it around just as an extra level of protection.
Thank you very much. I’m happy to use fail2ban, but am worried that it might not play nice with my current iptables rules. If the above config (my rules + fail2ban rules) looks good, please let me know. Specifically I was wondering if:
These rules:
-A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-nginx-http-auth -A INPUT -p tcp -m multiport --dports 22 -j fail2ban-ssh
make these rules irrelevant:
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
By the way, your tutorials have been great and I’ve learn a lot from them!
Hey brandon:
No, those lines will do different things. Hopefully I can explain why that is.
With your original configuration, a packet will be compared to each of the rules in your INPUT chain. At the end of your INPUT chain, you have a rule to drop any traffic that hasn’t matched so far. That’s why before that rule, you needed the original lines that explicitly allow generic traffic aimed at your web server and ssh daemon respectively. These will catch the web and ssh traffic and allow it to pass before it gets dropped.
The fail2ban rules that are added initially simply do one thing: at the very beginning of the INPUT chain, they will temporarily divert generic traffic aimed at those services to a new chain. These new chains are empty at the beginning except for one rule, which just hands control back to the INPUT chain, where it will continue on down the line, just like normal. These packets will still be dropped if they reach the end of the INPUT chain, just like they used to, so your original rules for the web server and ssh daemon are still necessary.
When a client is banned for failing to authenticate, fail2ban adds a new rule to the new fail2ban-* chain. The new rule checks whether the traffic is coming from the banned host. If it matches, the packets are dropped. If the traffic doesn’t match, it reaches the rule that returns the packet to the INPUT chain where it continues as described above.
So all that the initial fail2ban lines do is create an extra loop where additional checks can be made to deny specific clients. The flow is always returned to the main INPUT chain for traffic not matching a banned client. It doesn’t make any decision on the fate of the packet if it doesn’t match the ban list. That is left to the rules in your INPUT chain. The key rule to understand here is the
-j RETURNrule at the bottom of the new chains, which tell the packet to continue where it left off in the original INPUT chain.Great tutorial, as always! But I’m having a problem with fail2ban, when trying to get banned, I don’t see any modification in my iptables rules. I use a non-standard ssh port, let’s say 4422, when I changed that configuration in the jail.local the fail2ban rule no longer has the “-j fail2bah-ssh” at the end, I don’t know if this has anything to do with the issue.
Here are my iptable rules:
-P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT -N fail2ban-ssh -A INPUT -p tcp -m multiport --dports 4422 -A INPUT -i lo -j ACCEPT -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --dport 4422 -j ACCEPT -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -j DROP -A fail2ban-ssh -j RETURN
Any ideas?
Thanks!
Thanks for the tutorial. I have just joined Digital Ocean and didn’t realise how many useful tutorials it has.
I don’t quite get the mta = sendmail directive. For this to work, evidently you don’t need to install sendmail. I thought that you did, but I didn’t want to use sendmail, so I installed postfix and had fun configuring it. But, fail2ban really didn’t like me using postfix as the mta. I can post the error, but right now, I am just interested in generalisations, and I guess I can just go ahead and uninstall postfix, since fail2ban works without it anyway.
By the way, I configured postfix to only deal with local mail, as in mail originating on my machine only and delivered to root@localhost only.
@dconn6: postfix also installs a sendmail command. Take a look at “man sendmail” On a system using postfix, it will say “sendmail - Postfix to Sendmail compatibility interface” So even if you’re using postfix, just have sendmail for the mta directive.
Thank you!
I follows the tutorial and worked perfectly. However i am not sure what i did but now i try to trigger the rule by attempting failed logins for several times and it is not generating the rule that blocks the ip. Then i notice i got a notification. It mentioned that an ip attempted 37 times. Until then it generated the rule, blocked the ip and sent the notification. Why is it allowing so many attempts when the configuration I set was for 4 retries?
How can i fix this?
Thank you
@garsoltero: Make sure you restart it after making any configuration changes: <code>sudo service fail2ban restart</code> Also make sure <code>findtime</code> isn’t set too low.
@andrewSB: After integrating fail2ban, I can no longer access my site with https, any ideas as to what might be the issue?
‘sudo iptables -S’ returns this:
Thanks for this article!
I wonder why are we editing jail.local file instead of jail.conf? We copied local file from conf file and it started to be main configuration file!
How does it work?
I was stuck on the same issue… it’s just a local override, but if you left it in the .conf package updates would change your work without you knowing it. And yet it sort of does become the main file, because it’s local it know’s to take precedence over the package updates that didn’t get a chance to change it.
According to the Ubuntu man page on fail2ban, we can also add jail configurations into /etc/fail2ban/jail.d in addition to creating a jail.local file.
After following these instructions I tested fail2ban but it would not ban me after multiple wrong passwords. I need to do this also:
http://www.fail2ban.org/wiki/index.php/Fail2ban:Community_Portal#Count_.22Last_message_repeated_N_times.22_correctly
"It seems Fail2ban undercounts entries from syslog files such as /var/log/syslog and /var/log/auth.log, since it doesn’t seem to be aware that syslog may log “last message repeated N times” instead of the full message. For example, if an ssh attack occurs several times in quick succession, there may be only one entry “Failed password for someuser from 1.2.3.4 port 4307 ssh2” followed by “last message repeated 10 times”.
GNU/Linux distributions rsyslog solution: Tested in Ubuntu 10.04, should also work Centos/RHEL 5.9 or 6.X if rsyslog is used.
1.open /etc/rsyslog.conf 2.find RepeatedMsgReduction and change on to off 3.After that, restart rsyslog and fail2ban"
Thank you for the great tutorial. However, I ran into a problem. I had installed the “one click Wordpress install” and then installed Fail2ban using your instructions. Now when I try to login to my site, I get a “Welcome to nginx!” welcome page instead of wordpress. Please help.
Hi, this is my first post in this community and I must say that all the available tutorials here were very useful and they taught me to configure my own Magento LEMP+SSL-EV droplet. Just awesome learn all this in 3 weeks!
Until now it seems that all is running fine, and I’m using these iptables+fail2ban config:
[nginx-http-auth] enabled = true filter = nginx-http-auth port = http,https logpath = /var/log/nginx/error.log
[nginx-login] enabled = true filter = nginx-login action = iptables-multiport[name=NoLoginFailures, port=“http,https”] logpath = /var/log/nginx*/access.log bantime = 600 maxretry = 6
[nginx-badbots] enabled = true filter = apache-badbots action = iptables-multiport[name=BadBots, port=“http,https”] logpath = /var/log/nginx*/access.log bantime = 86400 maxretry = 1
Login filter /etc/fail2ban/filter.d/nginx-login.conf:
Blocks IPs that fail to authenticate using web application’s log in page
Scan access log for HTTP 200 + POST /sessions => failed log in
[Definition] failregex = ^<HOST> -.*POST /sessions HTTP/1.." 200 ignoreregex =
-P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT -N fail2ban-BadBots -N fail2ban-NoLoginFailures -N fail2ban-nginx-http-auth -N fail2ban-ssh -N fail2ban-ssh-ddos -A INPUT -p tcp -m multiport --dports 22 -j fail2ban-ssh-ddos -A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-BadBots -A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-NoLoginFailures -A INPUT -p tcp -m multiport --dports 80,443 -j fail2ban-nginx-http-auth -A INPUT -p tcp -m multiport --dports 28888 -j fail2ban-ssh -A INPUT -i lo -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT -A INPUT -p tcp -m tcp --dport 28888 -j ACCEPT -A INPUT -j DROP -A fail2ban-BadBots -j RETURN -A fail2ban-NoLoginFailures -j RETURN -A fail2ban-nginx-http-auth -j RETURN -A fail2ban-ssh -j RETURN -A fail2ban-ssh-ddos -j RETURN
My questions/doubts are:
Is This enough to mitigate the majority of attacks? Or, should I implement something more? Is there any redundancy with “my new” NoLoginFailures and nginx-http-auth default filter?
I’m asking your advice 'cause I’m kinda noob about this… Just kidding, I’m entirely noob… LOL
Thanks a lot!
There are various reasons why you shouldn’t DROP, but the most important is that the packets aren’t actually dropped, they are replied to in a way that says the port is open but unavailable due to timeout. On the other hand, REJECT will reply that the port is closed, which is less helpful to attackers. DROP lets the attacker know the network is working and there is something behind the port, REJECT will make the attacker think their network is broken or there is nothing there. Fail2Ban uses REJECT by default, which is good.
I wrote a thing on how to enable rate-limiting for nginx here.
After doing that, you can have fail2ban check the rate logs and ban for rate limit pests.
This will deter all web brute forcing.
In
/etc/fail2ban/jail.local:Create
/etc/fail2ban/filter.d/nginx-ratelimit:Then run
service fail2ban reloadQuestion:
When I run
sudo apt-get install nginx sendmail iptables-persistent, I get a window with the following:Current iptables rules can be saved to the configuration file /etc/iptables/rules.v4. These rules will then be loaded automatically during system startup.
Rules are only saved automatically during package installation. See the manual page of iptables-save(8) for instructions on keeping the rules file up-to-date.
Save current IPv4 rules? <Yes> <No>
What is recommended?
Many thanks, Andrea
I said “yes” but if you read my comment, I ran into some really big problems with iptables so maybe you should try “no” but I have no idea to be honest. :P
I’m stuck on the “Establish a Base Firewall” part. Whenever I enter anything to do with iptables, I get the following message:
If I try apt-get install insmod then it says the package cannot be found. I’m on Ubuntu 14.04, just to clarify.
I am stucked with the same problem too! :( I also answered YES to both ipv4 and ipv6 rules on iptables-persistent installation. I don’t really know what to do.
Now I solved my problem with the link below! https://www.digitalocean.com/community/questions/error-while-allowing-ssh-connections-on-ufw
Hello,
I hope someone is looking there. I have got some problems.
I configured my banning policy and SSH section like this:
But when i try to test it, fail2ban does not banning login attempt. Here is my fail2ban log:
Here iptables -S :
It’s been a long time since you wrote, and I’m a noob, but on the off chance this is still helpful, I think your problem is here:
I don’t think fail2ban knows what to do with ssh-4444. The iptables seems to reflect an ssh port of 22 from fail2ban. I suspect that changing ssh-4444 to 4444 will start to fix your problem.
Thank you for the tutorial. I believe that it is missing the key step of saving the configuration after setting up the rules. I suggest that after setting up the rules in the “Establish a Base Firewall” step, do: sudo iptables-save > /etc/iptables/rules.v4
Can we use Fail2ban with CSF together?
I ınstalled lamp before. Now I want to ınstall fail2ban. But for that we should install nginx. If I will ınstall all will there be any problem because of apache&nginx?
Clearly fail2ban is still using jail.conf based on checking the status and I can see it is not paying attention to jail.local. So I have questions:
I have an annoying problem, and I really want help with it. Every sunday the log files is being cleaned up both for fail2ban och auth.log and i have set an bantime to 1000 days and cheched all settings…
What can i do, whats the problem?
Are the iptables a reflection of what’s going on with ufw? or am I suppose to be running 2 separate firewalls?
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I’ve followed this tutorial and I can not get fail2ban to actually ban failed SSH attempts. I tried logging in repeatedly from another server and fail2ban did not seem to be aware of this. I can see the failed attempts by running
And then I see the following (server IP replaced with x by me)
However the output of
fail2ban-client status sshhere is:Here are samples of my config in jail.local (please note that I’ve moved the SSH port to 19232)
The output of iptables -S is
Additional info
Here is the output of
fail2ban-regex /var/log/auth.log /etc/fail2ban/filter.d/sshd.confDoes anyone have any ideas of what could be wrong here?
If anyone is having trouble connecting to their remote mysql server when they activate fail2ban with iptables rules I found a solution and it seems to be working: I added following rules;
The rules above gives access to MySQL database server from web server only.
Thanks!!! Very helpful!