Fighting dictionary attacks with Sshutout and Fail2ban
Protection against DoS
SSH has two jails: the one just mentioned and sshd-ddos. This jail is not designed to prevent attempts to guess passwords, but to counter denial-of-service (DoS) attacks that open connections to the SSH daemon without entering a password.The logfile contains messages like this in case of a DoS attack:
sshd: Did not receive identification string from 10.0.0.150
Although you could configure multiple regular expressions per jail, many admins will prefer to assign different ban times for distributed DoS (DDoS) attacks as opposed to failed login attempts. That is, splitting this into the SSH and sshd-ddos categories makes a lot of sense.
The SSH jail is the only one set to enabled = true by default; all other jails – including sshd-ddos – have to be enabled manually.
If a user enters the wrong password multiple times, the results are similar to the Sshutout results: An iptables rule is triggered and locks out all connections from the offending computer for the next five minutes (Figure 2).
Protection for other services follows the same pattern (Figure 3). If you have a number of login-protected web pages on your Apache web server, Fail2ban will give you a jail to match,
[apache] enabled = false port = http,https filter = apache-auth logpath = /var/log/apache*/*access.log maxretry = 3
which you need to modify slightly. The Apache version that I run writes error messages to a separate error.log file, and not to access.log. After setting enabled = true, you can enable the jail.
Tip: A more elegant approach than simply restarting the Fail2ban daemon, which could mean disabling active iptables rules, is to send the following command from the Fail2ban client to the server:
fail2ban-client start apache
This command tells the server to add the [apache] entry to the list of active jails. To try this out, I entered a number of invalid passwords, and a new iptables rule was activated.
Bug database has a bug of its own that could allow an intruder to create an unauthorized account.
Report focuses federal resources on achieving universal Internet access.
Leading browser makers say “no” to porous encryption algorithm
Report from the X-Force group says attackers are using TOR to hide their crimes
Future Firefox extensions will be compatible with Chrome.
Better read this if you bought your computer before 2011
Users should upgrade to the new version as soon as possible
Xen project announces a privilege escalation problem for Qemu host systems
Attackers can compromise an Android phone just by sending a text message
PC vendor will pre-install Ubuntu on portables in India.