Here's a handy guide to understand the readings of top and iftop in Linux. I hope someone finds it useful.
There's htop too, which I use it much to check out process and cpu usage, though, great tutorial, I would use this tut aswell
htop is superior to top in many ways, but top is superior to htop in many other ways. I suggest using both. Also, here's some other useful tools: vnstat — bandwidth monitoring, live pps/mbps traffic monitoring fail2ban — auto-ban IPs that try to bruteforce SSH. Can also work for a few other services. webmin — GUI frontend for basic Linux administration. I like using it for managing Apache and my firewall. varnish — Reverse proxy/cache for Apache/Nginx. Allows you to cache stuff, rewrite requests, do all sorts of mangling and adjustments on sent/received data, etc. Very useful for reducing the impact of GET floods on vulnerable pages. Cache is stored in RAM, you can adjust the size yourself. Configuration is somewhat complicated though. munin — Extremely useful server monitoring tool. Creates pretty graphs of all sorts of things. There's even a plugin out there (somewhere) that can graph player activity on MC servers.
Hmm... I'm gonna look up all of these. The SSH bruteforcing one shocked me. I never thought about that possibility. I have SSH open (on a nonstandard port) because the last time I went on vacation I left it closed and my server crashed and was down for a whole week. So I should get some sort of protection for it. >.< Thanks a lot, man! I'm sure these will all be fun to use.
According to my logs, there were 41,811 failed SSH logins in the last month (since August 12th). So yeah, it's important.
