Oudated variables and improvements

[QROkes]

Some variables are actually deprecated:

• kernel.maps_protect - was deprecated since kernel v2.6.28 more than 10 years ago.
• net.ipv4.tcp_tw_recycle - deprecated since v4.12
• kernel.exec-shield - No longer supported in sysctl settings.

Also I think in most recent linux versions "net.ipv4.tcp_congestion_control" BBR is better, instead of HTCP.

I like to add these variables to your configuration:

fs.nr_open=12000000
net.ipv4.tcp_sack=1
net.ipv4.tcp_mtu_probing = 1
net.ipv4.tcp_base_mss = 1024
net.ipv4.tcp_challenge_ack_limit = 999999999
net.ipv6.conf.default.router_solicitations = 0
net.ipv6.conf.default.accept_ra_rtr_pref = 0
net.ipv6.conf.default.accept_ra_pinfo = 0
net.ipv6.conf.default.accept_ra_defrtr = 0
net.ipv6.conf.default.dad_transmits = 0
net.ipv6.conf.default.max_addresses = 1