All Questions(server)

I'm trying to create a private key and having an issue.

When I use ssh-keygen -t rsa -b 4096 -C "[email protected]", I get a private key in the following format.

-----BEGIN OPENSSH PRIVATE KEY-----
uTo43HGophPo5awKC8hoOz4KseENpgHDLxe5UX+amx8YrWvZCvsYRh4/wnwxijYx
...
-----END OPENSSH PRIVATE KEY-----

And this is not being accepted for an application that I'm trying to use.

I'm expecting a key in the following RSA format.

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-128-CBC,25737CC2C70BFABADB1B4598BD8AB9E9

uTo43HGophPo5awKC8hoOz4KseENpgHDLxe5UX+amx8YrWvZCvsYRh4/wnwxijYx
...
-----END RSA PRIVATE KEY-----

How do I create the correct format? This is weird because every other mac I have creates the correct format, except the one I'm having problem with.

I'm on a fresh installed Mac OS Mojave

I want connections coming in on ppp0 on port 8001 to be routed to 192.168.1.200 on eth0 on port 8080.

I've got these two rules

-A PREROUTING  -p tcp -m tcp --dport 8001 -j DNAT --to-destination 192.168.1.200:8080

-A FORWARD -m state -p tcp -d 192.168.1.200 --dport 8080 --state NEW,ESTABLISHED,RELATED -j ACCEPT

and it doesn't work. What am I missing?

I have the following data in my DNS zone file for my domain:

$ORIGIN mydomain.com.
@       IN      A       208.X.Y.Z
mail    IN      A       208.X.Y.Z
... etc..

What does the @ line mean? I know what an A record is.. but a host with an ampersand at sign?

I schedule some tasks using crontab.

What will happen if my computer is shutdown or turned off during the time when cron was scheduled to do something?

Does each missed cron job run after computer is turned on, or are missed jobs for that day ignored? If missed jobs don't resume, is there any way to configure cron such that it runs the missed tasks after the computer is turned back on?

What is a simple way in Windows to test if traffic gets through to a specific port on a remote machine?