The purpose of this post is to introduce a user to the nmap command line tool to scan a host and/or network, so to find out the possible vulnerable points in the hosts. You will also learn how to use Nmap for offensive and defensive purposes.
via Top 30 Nmap Command Examples For Sys/Network Admins.
Nmap can be very useful which is why I have a link to it in the Tools section on this page.
Sysinternals Suite
The entire set of Sysinternals Utilities rolled up into a single download.
Just a shout out to an excellent set of PC diagnostic tools since I had to recently download and use tcpview.exe.
If you decided not to go hosted and are thinking about implementing a premise-based VoIP solution or you already have a system in place, here are some of the methods which are used to secure PBX systems.
Much of the Internet’s end-to-end security relies on the SSL protocol, along with its underlying X.509 certificate infrastructure. However, the system remains quite brittle due to its liberal delegation of signing authority: a single compromised certification authority undermines trust globally. The ICSI Notary helps clients to identify malicious certificates by providing a third-party perspective on what they should expect to receive from a server. While similar in spirit to existing efforts, such as Convergence and the EFF’s SSL observatory, our notary collects certificates passively from live upstream traffic at multiple independent Internet sites, aggregating them into a central database in near-realtime.
To solve the problem I used Perl (feel free to use your favorite language) to open a pcap file and do some analysis. Let us look at finding sessions where the client sent data but the server didn’t send any data in response. To make it easy I’ve included all the steps I took and, where appropriate, the code. Since the point is to illustrate how to use script language like Perl to do the job, the code is greatly simplified. For the convenience of reader, the complete code is listed at the end.
In Unix/Linux you can execute your perl scripts by typing “perl <filename>” at command prompt. But before you do that make sure you have both Perl and its Tk module. Most linux distributions have perl – but quite a few don’t have the Tk module. Make sure that the system you are using have the Tk module. If you don’t have it, go to http://www.cpan.org and download the perl module. Or you can use the perl’s CPAN module to install the Tk module. To do this, open a terminal and enter the following command
perl -MCPAN -e shell
cpan> install Bundle::CPAN
cpan> reload cpan
cpan> install Tk
To enable the ability to capture traffic sent and received on other switch ports, Cisco Catalyst switches include a feature called the switch port analyzer feature (SPAN), as well as remote SPAN (RSPAN) and VLAN access control lists (VACLs).
SPAN is the traditional method of monitoring LAN traffic on Cisco switches. SPAN uses the concept of mirroring traffic from a set of source ports to a single destination port, which has a network capture tool connected to it.
The automation of these Top 20 Controls will radically lower the cost of security while improving its effectiveness. The US State Department, under CISO John Streufert, has already demonstrated more than 94% reduction in “measured” security risk through the rigorous automation and measurement of the Top 20 Controls.
As interns, we recently completed an assignment to benchmark read, write, modify and authentication performance of different Directory servers. This two part blog entry reports on our findings. This first part introduces the directory servers we subjected to our benchmark. The second part contains the benchmark results and conclusions.
via IS4U blog.
This Linux based firewall is controlled by the program called iptables to handles filtering for IPv4, and ip6tables handles filtering for IPv6. I strongly recommend that you first read our quick tutorial that explains how to configure a host-based firewall called Netfilter (iptables) under CentOS / RHEL / Fedora / Redhat Enterprise Linux. This post list most common iptables solutions required by a new Linux user to secure his or her Linux operating system from intruders.