We will also be setting up VLANs for other network segments. Once those VLANs are active, going into Firewall > Groups and ...

When we began this series, we discussed the ICMP (Internet Control Message Protocol). This protocol is the basis for two widely used applications, ping and traceroute. In this lesson and the next, we ...

In its second IOS security bulletin in a week, Cisco warned that a common management protocol used on the Internet could be used to launch denial-of-service attacks against Cisco routers and other ...

Does anyone have some good links for modern best practices? Internally we have some disagreement about whether we should allow or block ICMP and traceroute (well, UDP, since the ICMP policy would ...

As much as 38 percent of the Internet’s domain name lookup servers are vulnerable to a new attack that allows hackers to send victims to maliciously spoofed addresses masquerading as legitimate ...

Yes, it’s true! I’m the author of ping for UNIX. Ping is a little thousand-line hack that I wrote in an evening which practically everyone seems to know about. I named it after the sound that a sonar ...

The current IP address scheme of 32-bit words is fast becoming inadequate. It would appear that 2 32 = 4 294 967 296 combinations of addresses should be enough for everybody, but in practice this is ...

Researchers warned that a low-volume BlackNurse DoS attack launched via a single laptop can bring some firewalls to their knees An attacker doesn’t need an IoT botnet or massive resources for a denial ...

Network tools are essential for solving issues with a computer network that is not performing as it should. There are quite a few things can do to aid in returning a network to its rightful state, and ...

We’ve all been online from home a bit more than usual lately, in ways that often stretch the limits of what our ISP can muster. You know the signs — audio that drops out, video sessions that make you ...

Get ready to patch your Windows systems as a new bug has been discovered that can lead to the dreaded Blue Screen of Death. This bug, labeled the “Bad Neighbor” exploit (CVE-2020-16898), enables an ...

As part of VoIP threat series, I’d like to introduce “Call Flooding” which is the typical VoIP attack against availability (refer to previous blog “VoIP Threat Taxonomy” to know the category).