Viewing a Certificate Using OpenSSL

I have started taking Ed Harmoush’s Practical TLS course to learn more about TLS and certificates. When learning about TLS, you want to inspect different certificates to see the various fields and see how different organizations use certificates differently. As always, Linux comes with a great set of tools to work with certificates in the form of OpenSSL. In this post, I will show how to download a certificate and discuss some of the fields that are present in the certificate.

To get the certificate, we will use openssl with s_client and connect to a web site. I’m using twitter.com in this example:

openssl s_client -connect twitter.com:443
CONNECTED(00000003)
depth=2 C = US, O = DigiCert Inc, OU = www.digicert.com, CN = DigiCert Global Root CA
verify return:1
depth=1 C = US, O = DigiCert Inc, CN = DigiCert TLS Hybrid ECC SHA384 2020 CA1
verify return:1
depth=0 C = US, ST = California, L = San Francisco, O = "Twitter, Inc.", CN = twitter.com
verify return:1
---
Certificate chain
 0 s:C = US, ST = California, L = San Francisco, O = "Twitter, Inc.", CN = twitter.com
   i:C = US, O =  Continue reading

netlab Multi-Platform Custom Configuration Templates

In the Building a BGP Anycast Lab I described how you could use custom configuration templates to extend the netlab functionality.

That example used Cisco IOS… but what if you want to test the same functionality on multiple platforms? netlab provides a nice trick: the custom configuration template could point to a directory with platform-specific templates. Let me show you how that works…

Read more …

Multi-Platform Custom Configuration Templates in netsim-tools

In the Building a BGP Anycast Lab I described how you could use custom configuration templates to extend the functionality of netsim-tools.

That example used Cisco IOS… but what if you want to test the same functionality on multiple platforms? netsim-tools provides a nice trick: the custom configuration template could point to a directory with platform-specific templates. Let me show you how that works…

Read more …

Weekend Reads 042222


Agencies of the US Government have issued a joint warning that hackers have revealed their capability to gain full system access to industrial control systems that might help enemy states sabotage critical infrastructure.


Whether you consider them black swan cyber events or not, the SolarWinds attack and the Log4Shell exploit stressed some of the key ways in which organizations can prepare themselves and prevent crises.


The serious lesson from that is to acknowledge but forgive errors. “He’s said, many times, that he knew at that moment it was going to be OK,” Ellis says. “Creating a safe culture requires a lot of practices, and one of them is closure. Humor is a great way to provide closure because you rarely laugh about something that is still creating tension.”


To say that data governance and data compliance are rapidly becoming areas of immense strategic importance for businesses would be an understatement. Governments worldwide already have data protection laws in place or are busy drafting these laws.


On Sunday, an attacker managed to drain around $182 million of cryptocurrency from Beanstalk Farms, a decentralized finance (DeFi) project aimed at balancing the supply and demand of different cryptocurrency assets. Notably, the attack Continue reading

OMG: Hop-by-Hop Path MTU Discovery

Straight from the “Bad Ideas Never Die” (see also RFC 1925 Rule 11) department: Geoff Huston described a proposal to use hop-by-hop IPv6 extension headers to implement Path MTU Discovery. In his words:

It is a rare situation when you can create an outcome from two somewhat broken technologies where the outcome is not also broken.

IETF should put rules in place similar to the ones used by the patent office (Thou Shalt Not Patent Perpetual Motion Machine), but unfortunately we’re way past that point. Back to Geoff:

It appears that the IETF has decided that volume is far easier to achieve than quality. These days, what the IETF is generating as RFCs is pretty much what the IETF accused the OSI folk of producing back then: Nothing more than voluminous paperware about vapourware!

OMG: Hop-by-Hop Path MTU Discovery

Straight from the “Bad Ideas Never Die” (see also RFC 1925 Rule 11) department: Geoff Huston described a proposal to use hop-by-hop IPv6 extension headers to implement Path MTU Discovery. In his words:

It is a rare situation when you can create an outcome from two somewhat broken technologies where the outcome is not also broken.

IETF should put rules in place similar to the ones used by the patent office (Thou Shalt Not Patent Perpetual Motion Machine), but unfortunately we’re way past that point. Back to Geoff:

It appears that the IETF has decided that volume is far easier to achieve than quality. These days, what the IETF is generating as RFCs is pretty much what the IETF accused the OSI folk of producing back then: Nothing more than voluminous paperware about vapourware!

Heavy Networking 627: Network Automation As A Business Culture

The business benefits of network automation are sometimes lost in discussion about technology and tools. Guest Tim Fiola joins this episode of Heavy Networking to discuss how to engage the business at a cultural level so that network automation is properly embraced and supported by management.

The post Heavy Networking 627: Network Automation As A Business Culture appeared first on Packet Pushers.

BGP AS Override Feature Explained in 2022

BGP AS Override needs to be understood well in order to understand the BGP loop prevention behavior, But why BGP AS Override might create a dangerous situation, and what are the alternatives of BGP AS Override will be explained in this post.

What is BGP AS Override

BGP AS Override feature is used to change the AS number or numbers in the AS Path attribute. Without BGP AS-Override, let’s see what would happen.

BGP AS Override

In this topology, Customer BGP AS is AS 100. The customer has two locations.

Service Provider, in the middle, let’s say providing MPLS VPN service for the customer.

As you can understand from the topology, Service Provider is running EBGP with the Customer, because they have different BGP Autonomous Systems.

The service provider in the above topology has BGP AS 200.

Left customer router, when it advertises BGP update message to the R2, R2 sends to R3 and when R3 sends to R4, R4 wouldn’t accept the BGP update,

When R4 receives that update, it will check the AS-Path attribute and would see its own BGP AS number in the AS Path.

Thus is by default rejected, due to EBGP loop prevention.

If the router sees its Continue reading

Ease of Use or Ease of Repair

HammerAndSaw

Have you tried to repair a mobile device recently? Like an iPad or an MacBook? The odds are good you’ve never even tried to take one apart, let alone put in replacement parts. Devices like these are notorious to try and repair because they aren’t designed to be fixed by a normal person.

I’ve recently wondered why it’s so hard to repair things like this. I can recall opening up my old Tandy Sensation computer to add a Sound Blaster card and some more RAM back in the 90s but there’s no way I could do that today, even if the devices were designed to allow that to happen. In my thinking, I realized why that might be.

Build to Rebuild

When you look at the way that car engine bays were designed in the 80s and 90s you might be surprised to see lots of wasted space. There’s room to practically crawl in beside the engine and take a nap. Why is that? Why waste all that space? Well, if you’re a mechanic that wants to get up close and personal with some part of the engine you want all the space you can find. You’d rather waste a Continue reading

On Securing BGP

The US Federal Communications Commission recently asked for comments on securing Internet routing. While I worked on the responses offered by various organizations, I also put in my own response as an individual, which I’ve included below.

I am not providing this answer as a representative of any organization, but rather as an individual with long experience in the global standards and operations communities surrounding the Internet, and with long experience in routing and routing security.

I completely agree with the Notice of Inquiry that “networks are essential to the daily functioning of critical infrastructure [yet they] can be vulnerable to attack” due to insecurities in the BGP protocol. While proposed solutions exist that would increase the security of the BGP routing system, only some of these mechanisms are being widely deployed. This response will consider some of the reasons existing proposals are not deployed and suggest some avenues the Commission might explore to aid the community in developing and deploying solutions.

9: Measuring BGP Security.
At this point, I only know of the systems mentioned in the query for measuring BGP routing security incidents. There have been attempts to build other systems, but none of these systems have been Continue reading

BGP Route Reflector vs Confederation

BGP Route Reflector – RR vs Confederation is one of the first things Network Engineers would like to understand when they learn both of these Internal BGP scalability mechanisms. For those who don’t know the basics of these mechanisms, please read BGP Route Reflector in Plain English and BGP Confederation Blog posts from the website first.

BGP Route Reflector vs BGP Confederation

There are many differences when we compare Confederation vs Route Reflector and in this post, some of the items in the comparison chart will be explained.

 

bgp route reflector vs confederation

BGP Route Reflector vs Confederation Scalability

Both of these techniques are used in Internal BGP for scalability purposes. But BGP RR changes the Full Mesh IBGP topologies to the Hub and Spoke. BGP confederation divides the Autonomous System into the sub-ASes but inside every Sub-AS, IBGP rules are applied.

Inside BGP Sub Autonomous System, full Mesh IBGP or Route Reflector is used. So, we consider BGP RR compare to Confederation to be more scalable because inside Sub-AS still full-mesh IBGP might be used.

If RR inside Sub-AS is deployed, then configuration complexity would increase.

BGP Route Reflector vs Confederation Loop Prevention

BGP Route Reflector in order to prevent the routing loop Continue reading

Happy Earth Day: Announcing Green Compute open beta

Happy Earth Day: Announcing Green Compute open beta
Happy Earth Day: Announcing Green Compute open beta

At Cloudflare, we are on a mission to help build a better Internet. We continue to grow our network, and it is important for us to do so responsibly.

Since Earth Day 2021, some pieces of this effort have included:

And we are just getting started. We are working to make the Cloudflare network — and our customers’ websites, applications, and networks — as efficient as possible in terms of design, hardware, systems, and protocols. After all, we do not want to lose sight of our responsibilities to our home: our planet Earth.

Green Compute for Workers Cron Triggers

During Impact Week last year, we began testing Green Compute in a closed beta. Green Compute makes Workers Cron Triggers run only in facilities that are powered by renewable energy. We are hoping to incentivize more facilities to implement responsible climate and energy policies.

With Green Compute enabled, Workers Cron Triggers will run Continue reading

BGP vs EIGRP 10 Important differences between them!

In this post, we will compare BGP and EIGRP. We will look at some of the important aspects when we compare BGP vs EIGRP. Although EIGRP is used as an IGP and BGP is used mainly as an External routing protocol, we will compare from many different design aspects. Also, BGP can be used as an Internal IGP protocol as well and we will take that into consideration as well.

bgp vs eigrp

 

We prepared the above comparison chart for BGP vs EIGRP comparison. We will look at some of those important Comparison criteria from a design point of view.

BGP vs EIGRP Scalability

One of the biggest reasons we choose BGP, not EIGRP is Scalability. BGP is used as a Global Internet routing protocol and as of 2022, the Global routing table size for IPv4 unicast prefixes is around 900 000. So almost a million prefixes we carry over BGP on the Internet.

So, proven scalability for BGP we can say. EIGRP usually can carry only a couple of thousands of prefixes, this is one of the reasons, EIGRPrp is used as an Internal dynamic routing protocol, not over the Internet.

BGP vs EIGRP in Full Mesh, Ring and Hub and Continue reading

The Network Anyverse

An explanation of my Network Anyverse Strategy. Normal practice for data networking was that technology was narrow: fixed bandwidth, focus on selected technology, and there were only service I  look at the progression of Networking in the new future that I sometimes call the Four A’s:  Anyhow Anywhere Anytime Anyway Anywhere Distributed work means that […]
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