Tag Archives: network

CLN 2015 Designated VIPs

I wanted to take a moment and give a well-deserved congratulations to the 2015 Cisco Learning Network Designated VIPs. These fine folks spend a ton of time giving back to the community by helping others in their learning process. New … Continue reading

Posted in Blogroll, Career, Certification, General, Technology | Tagged , , | 4 Comments

Discard Routing for RFC1918 Addresses

While working with firewalls for the last few years, I’ve seen many logs polluted with scanning traffic. Obviously this is the type of thing that I want to see when someone is legitimately scanning, or attempting to scan, through the firewall. However, … Continue reading

Posted in CCIE Security, CCNA Security, Certification, General, Network, Technology | Tagged , | 2 Comments

The Longest Match Rule

One of the the concepts that comes up occasionally is that of precedence. For example, one might consider the following routing table entries. ip route 0.0.0.0 0.0.0.0 1.1.1.1 //default route ip route 192.168.0.0 255.255.0.0 1.1.1.2 //supernet/cidr route ip route 192.168.1.0 255.255.255.0 … Continue reading

Posted in CCNA, Certification, General, Network, Technology | Tagged | 3 Comments

Native TFTP and FTP Server in OSX

As a System Engineer, I do occasionally have to do real field work. When that happens, having access to a TFTP and FTP server is sometimes required. Although the [lack of] UI makes the use counterintuitive, these tools are available in OSX. This … Continue reading

Posted in Certification, General, Network, Technology | Tagged | 3 Comments

Securing Your Connection Anywhere You Go

We all know that there are a lot of incomplete security models. Firesheep made this fact painfully obvious to those who regularly work from public hotspots. Although this issue extends beyond insecure wireless deployments, unencrypted hotspots are an easy target. … Continue reading

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Validation Testing Matters

A couple of weeks ago, a CLN Member Posted a question with the heading Does ASA drop active session. The specific question was as follows– I have a time based ACL configured on a Cisco ASA. I need to know if the … Continue reading

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Positioning an IT Conversation

About a  week ago, I took my wife’s van to the shop. The main issue was it was making a popping noise in the front end. I only observed the noise when steering sharply and the vehicle was in motion. Typically … Continue reading

Posted in Career, Rant, Technology | Tagged , , | 1 Comment

Google and Cloudflare: Encrypting the WWW

A couple of months ago, Google announced that it had started using SSL as a factor in SEO ranking. Since the search giant is the referrer for most website traffic, this is the type of announcement that gets the attention … Continue reading

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Using Ping Sweep to Find MTU Ceiling

Earlier this week I had breakfast with a very interesting group. One of those present had an extensive history with Cisco systems. We talked about his tenure and several of the projects that he had been involved in. For some … Continue reading

Posted in Network, Technology | Tagged , , | 1 Comment

Classic IOS as a DNS Server

There is an occasional need for a DNS server in the absence of a dedicated host. This may occur in the following situations– Using PAT, Public DNS may return a non-RFC1918 address for internal server Lab/Demo Environment Other Name Resolution challenges in SOHO, … Continue reading

Posted in Network, Technology | Tagged , | 2 Comments

IP Subnetting Part 5: Subnetting Across the Octet Boundary

Throughout this series, we have examined several fundamental building blocks of subnetting. In IP Subnetting Part 4, we looked at what was required to subnet a Class C network. This article takes the fundamentals one step further and looks at … Continue reading

Posted in CCNA, Certification, General, Network, Technology | Tagged , , , , | 3 Comments

Using NVI to Allow Internal Hosts to Connect to Public Addresses of Hosted Servers

IP NAT is a very common configuration. One of the challenges that sometimes surfaces is the need for internal hosts to connect to the public address of a locally hosted server. Anyone who has tried to configure something like the following has … Continue reading

Posted in CCNA, Certification, General, Network, Security, Technology | Tagged , , , | 8 Comments