myITmicroblog

Today I’d like to implement L2 firewall on cisco router using CBAC. A few months ago I did similar lab but today I’d like to add a new requirement: allowing on DHCP packets across the L2 firewall. fa1 / 0 / 11 fa1 / 0 / 13 /---- \ \ ----------------------- / / ---- \ | R2 |----------| SW |----------| R3 | \- ---/ \ ----------------------- / \- ---/ gig0 / 0 / \ /---- \ / \ fa0 / 0 10.0 . 0.1 fa1 / 0 / 9 - | R1 |- fa1 / 0 / 10 dhcp client dhcp server / \- ---/ \ gig0 / 0 | gig0 / 1 | VLAN 10 L2 FW VLAN 20 --------------------------->|<---------------------------- At the beginning, to test connectivity and CBAC, the interface fa0/0 will...

Today I would like to smash your confidence about the security of your organization. You spent hundreds of dollars or euros on your security devices and you think you are safe. I believe there are many organizations like yours that think the same thing. Once they become victims, they realize they are not as safe as they had thought. Let’s talk about DOS/DDOS attacks. I think most people have some knowledge about them. Today we should not talk only about DOS attacks because the risk of being seriously impacted is very low. Most network devices can easily mitigate such attacks because they come from one source IP address. The situation is different when we receive illegitimate traffic from many IP addresses. There are two possibilities here: we can be flooded by traffic from a real, existing source IP address or addresses; or there is one real source IP, but the packets contain random source IPs, which means you are not able to block them easily. We can distinguish the fol...