JMX ports to open in firewall for jconsole to Cassandra

1. Port 7199
1. Used for about a dozen packets when JMX connection first made
1. A handshake of sorts
2. Probably sets up the agreement on which high port to connect to, used below
1. Similar to SIP
2. Similar to old FTP
2. Not used again after initial handshake
2. Port range 55000 to 55999
1. To see these packets, on JVM server
1. tcpdump -nn ! port 22 and host <jconsole client IP> (not literal, replace this)
3. If jconsole starts showing graphs, you are connected

To run jconsole directly on the server via VNC, see this article: http://sysadminandnetworking.blogspot.com/

Tricks and Tips

1. If you don't want to expose 1000 ports to the world for some reason
1. Open all ports on firewall in front of JVM server
2. On JVM server: tcpdump -nn ! port 22 and host <jconsole client IP>
3. Start jconsole connection on client machine
4. Watch to see which port JVM server is trying to reach jconsole client via
5. Close all but that port in the firewall, will be between 55000-55999
2. Do a local experiment to a local JVM JMX-able application if unsure of good jconsole connection result
3. Get your external IP from where you are running jconsole client
1. CLI: curl http://ipaddr.me
2. Or web browser: http://ipaddr.me

Quote: ACK packets and Quality of Service (qos)

"When you download, your computer needs to send (upload) ACK packets. These are basically saying "yep, I got that part of the download OK". If the computer you are downloading from detects that an ACK has not been received, it assumes that the data was not received and sends it again. The rate at which ACKs are sent back is also used to help determine the maximum speed that you can download data at, so it's important that ACKs get sent as soon as possible and don't get dropped in order to keep your downloads flowing fast. Also, repeatedly dropped ACKs can result in dropped connections, web page time-outs etc."

pfsense under Virtualbox

This is very brief. Not completely complete. An outline. A hint.

1. Download pfsense iso
2. Download Ubuntu Desktop iso
3. Create a VM for the pfsense
1. two interfaces
1. Adaper 1
   
2. Enable Network Adapter
   
3. NAT
1. Adaper 2
   
1. Enable Network Adapter
2. Internal Network
1. intnet
2. add the pfsense iso as a Storage
1. Empty
2. On the far right, there is a disk icon with a drop-down arrow
3. Choose a virtual CD/DVD disk file...
4. Select the pfsense iso on your local drive
3. OK
4. Boot the pfsense and hit "I" (capital eye) at the appropriate time to install pfsense to the VM's hard drive
5. em0 and em1 will be the interfaces to use 
1. not found automatically in my case
6. Rest of pfsense install not covered here
7. Install Ubuntu as normal
1. Adapter 1
1. use intnet
8. Start up Ubuntu desktop and log into 192.168.1.1or some similar gateway IP

Your host computer will not be able to hit the pfsense because your host is considered "outside the firewall". Hence, the trick to use an "inside man", an "inside computer" to reach the pfsense.

NOTE: Did you get stuck, blocked, lost? Let me know on which step, thanks.