SMANET_Midterm_Report_13July03.doc

The packet received from the network is placed in the

Info icon This preview shows pages 3–7. Sign up to view the full content.

View Full Document Right Arrow Icon
The packet received from the network is placed in the PREROUTING chain. There, a routing decision is made to either process the packet locally or to forward it to another node in the network. If it is to be locally processed, the packet is placed on the INPUT chain. If it is to be forwarded, it is placed on the FORWARD chain. While in the INPUT and FORWARD chains, a packet can be filtered. The criteria for accepting or dropping a packet in one of these two chains can be specified by the firewall software.
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Figure 4 Packet Chain Flow 3.2 Linux “iptables” Facility
Image of page 4
The Linux operating system provides a packet filtering facility known as “iptables.” This facility allows filtering rules to be defined. The rules allow packets to be dropped or accepted based on match criteria. The general syntax of an iptables statement is defined below in Table 1. An iptables statement can drop or accept a packet from the INPUT or FORWARD chains based on the specified match criteria. iptables [-t table ] command [match] [target/jump] Table 1 iptables statement 3.3 Node Firewall Filter Table 2 below shows the script executed by a MANET node to implement its firewall. The script is comprised of iptables statements that define the packet filtering criteria. #!/bin/sh # NODE-FILTER # eth0: wireless port # eth0 is sole communications port # DROP all wireless packets from the INPUT and FORWARD chains # except those with the following MAC addresses: # 00:09:B7:7B:B2:58 Cisco 350 PCI # 00:0A:B7:8B:5C:1D Cisco 350 PCMCIA # Set default policy on INPUT & FORWARD chains to DROP iptables -P INPUT DROP iptables -P FORWARD DROP # Apply INPUT chain filtering to wireless port eth0 iptables -A INPUT -i eth0 -p ALL -m mac --mac-source 00:09:B7:7B:B2:58 -j ACCEPT iptables -A INPUT -i eth0 -p ALL -m mac --mac-source 00:0A:B7:8B:5C:1D -j ACCEPT # Apply FORWARD chain filtering to wireless port eth0 iptables -A FORWARD -i eth0 -p ALL -m mac --mac-source 00:09:B7:7B:B2:58 -j ACCEPT iptables -A FORWARD -i eth0 -p ALL -m mac --mac-source 00:0A:B7:8B:5C:1D -j ACCEPT Table 2 Node Filter This firewall is designed to allow wireless communications between wireless nodes with specific media access control (MAC) addresses. Each wireless device conforming to the IEEE 802.11
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
standard has a unique MAC address. This firewall will drop all wireless packets that do not have one of the two requisite MAC addresses. In this script, the first two iptables statements specify that all packets on the INPUT and FORWARD chains will be dropped unless they meet the acceptance criteria defined in the iptables statements that follow. The next two iptables statements specify that all packets in the INPUT chain from the wireless port (eth0) with two specific MAC addresses will be accepted. The last two iptables statements specify the same criteria for packets on the FORWARD chain.
Image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern