snitch | Language agnostic tool that collects TODOs

Can anyone explain which value should be put in order to disable dynamic_snitch? im not sure if 0 or high number (50+?)

I'm working with Cassandra 3.x and Phantom driver (scala), and modifying my Cassandra deployment from a simple, three nodes cluster to a multi datacenter Cassandra deployment that consists of two datacenters:

1. Transactional - the "main" datacenter, to which all reads/writes occur (except for reads/writes done by some analytics job).
2. Analytics - a datacenter used for analytics purposes only. The analytics job should operate (i.e. read/write to) on this datacenter.

Both datacenters are configured with the proper snitch and replication factor strategies.

Based on this article ("Workload Separation" section), I'm supposed to be able to read/write from the "Transactional" datacenter, and run analytics jobs on the "Analytics" datacenter however, I'm not sure how to get this to work with the phantom driver.

How can I configure the driver to read/write from the proper datacenter?

Will setting the hosts in ContactPoints class to nodes from the Transactional datacenter only do the trick?

My app has a Flask backend and an Angular/Electron frontend. The app runs locally on Mac Catalina. Flask, Celery and Redis are in separate docker containers, while the frontend is outside Docker. The Flask container is listening on port 0.0.0.0:5078. I've set CORS policy to allow messages from "127.0.0.1:4200" only, sent by the frontend. There's no need for internet connections. The backend containers will be launched by the frontend by emulating a terminal command. I'll install the app remotely on non-technical users' Catalina MacBooks.

Question: According to Docker might be exposing ports to the world, Beware of exposing ports in Docker and Docker not blocked by macOS firewall, this use of 0.0.0.0:5078 is a security threat. How can I resolve this threat, eg by block ing any external connections to this port?

Here's some python 3.8 code

I have a cassandra cluster with 5 nodes that is using EC2 snitch but for the new node I want to add I want to use GossipingPropertyFileSnitch. Is it okay to have this node with a different snitch, will it cause any impact to the schema or schema versions?

I have a Cassandra cluster with two nodes with simple replication strategy.

Everything worked well until one of nodes crashed. I recovered the crashed node by cloning the remaining node virtual machine (so we cloned a file system), and updated the listening and RPC address.

Now I keep getting the following strange error.

When I am running each single node, everything is working well. But when I am starting the second node, the first one falls back with an error!

When using a mobile Android Wi-Fi hot spot on macOS Catalina and MenuMeters utility to see total mobile traffic I noticed that every time I launch iOS Simulator (tested on iPhone Pro Max and iPhone SE 2nd generation both with iOS 13.5) it starts downloading huge amounts of data (approx. 450-800 MB) on every launch, so it gets rather expensive. I know that's Simulator because when I quit it traffic stops.

So I'd like to find out what and why Simulator may download maybe to try to block/work around this expensive operations.

I tried to use Charles and Proxyman to detect addresses Simulator could connect to - but with no avail, I cannot see this hundreds of megabytes there. Another option was Wireshark, but I do not know how I could use it to get what I want (as I imagine it should be some addresses from where Simulator could download data).

Could you please give me some advices how to get needed info with these applications or in some other way.

Edit

Thanks to accepted answer and Little Snitch I was able to catch and block "evil" connection

As I am a newbie to Cassandra, I was confused with this term known as 'fast replica'. Basically what I know is dynamic snitch identifies the faster replica during the reading process and data from the faster replica is compared with the other replicas with the help of hash(for every message) and if the data is consistent then data from the fast replica is sent to the client or replicas go under the read repair(if the read consistency level is not met). What does exactly 'fast replica' means? Does it mean the read query doesn't need to query other nodes for the data? Please guide me through it. I couldn't find any relevant SO posts for this.

After cassandra install via sudo apt install -y cassandra, cassandra is running, but I have not yet configured cassandra.yaml and cassandra-topology.properties. Once I configure them cassandra won't start because Cannot start node if snitch's data center (0) differs from previous data center (datacenter1)

cassandra service (3.11.5) stops automatically after it starts/restart on AWS linux.

I have fresh installation of cassandra on new instance of AWS linux (t3.xlarge) and