Tag: hackers

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Securing Ajax and Web Services

It is undeniable that Web services and AJAX-ified interfaces are the trend now. Application that utilizes internet to retrieve data (such as mobile application or other thin client) uses web services alongside with its data format. AJAX-ified interface and website gives a modern and edgy look can make websites more attractive and can create great impression to the users.

However the issue of the web application security would still remain the same, if not more challenging, since there are so many ways to exploit the vulnerability of websites that utilizes Web Services and AJAX transfers on the background.

Therefore, it is imperative to use the right technique in order to evaluate the security of these services before deploying them out in the open.

For that matter, now I’m currently reading Ajax Security (Hoffman,B. & Sullivan, B.) and Securing Ajax applications (Wells, C.) which in my opinion is a pretty good start for somebody like me to understand common methods for securing web services and websites which uses AJAX heavily.

Hopefully the situation would improved as there are a lot of campaigns around to raise the state of awareness of web application security.

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Iptables rule to safeguard SSH server from crackers

Secured Shell or SSH is a service to enable users to access remote system securely. However, SSH servers depending on password-based authentication might be vulnerable to dictionary-based (or brute-force) attacks by crackers.

Luckily iptables can be used with ‘–limit-burst‘ and ‘–limit’ option to reduce the number of attempts and connection that a cracking tool can make in a period of time.

For example, in order to limit an IP address to making only 5 connections per minute in burst of 2 connections, you can use this iptables rules:

iptables -A INPUT -p tcp --dport ssh -m limit --limit 5/minute --limit-burst 2 -j ACCEPT

This will result in the iptables will only allow up to 5 connections per minute with 2 maximum initial number of connections, which will make any brute-force or dictionary-based attack uneconomical/unfeasible for the server.

Read more about iptables –limit and –limit-burst in Linux Iptables Limit the number of incoming tcp connection / syn-flood attacks