Linux tricks

linux-tricks

### Kill process and all its children
kill -- -$(ps -o pgid= $PID | grep -o '[0-9]*')   (signal TERM)
kill -9 -$(ps -o pgid= $PID | grep -o '[0-9]*')   (signal KILL)

### FIND TOP MEMORY USERS
ps aux | awk '{print $2, $4, $11}' | sort -k2rn | head -n 10

### SSH menu
~C

### SSH PORT FORWARDING
ssh TARGET -L127.0.0.1:1234:127.0.0.1:2345
   your localhost port 1234 is mapped to TARGET:2345
ssh TARGET -R127.0.0.1:1234:127.0.0.1:2345
   for reverse
ssh user@jumphost -L127.0.0.1:19990:TARGET:22
   same port forwarding above, but through a jumphost if you don't have direct access to TARGET
   
### FIND PROCESSES RUNNING MORE THAN 4 DAYS
ps -eo pid,etime,args | awk 'substr($2,1,index($2,"-")-1)>4

### FIND FILES NOT OWNED BY USER
find . \! -user foo -print

### IPTABLES DROP ALL OUTBOUND CONNS USING SOURCE & DEST PORTS
Allow binding to source port range: sudo iptables -I OUTPUT -p tcp --dport <dest_port> -m multiport --sports <range e.g.: 1:1023> -j ACCEPT
Block binding to all ports: sudo iptables -A OUTPUT -p tcp --dport <dest_port> -j DROP