#!/bin/bash
# Linux Kernel Optimization
# Supported platforms: CentOS/RedHat 7+, Debian 9+, and Ubuntu 16+
[ "$(id -u)" != "0" ] && { echo "Error: You must be root to run this script"; exit 1; }

[ -e /etc/security/limits.d/*nproc.conf ] && rename nproc.conf nproc.conf_bk /etc/security/limits.d/*nproc.conf
[ -f /etc/pam.d/common-session ] && [ -z "$(grep 'session required pam_limits.so' /etc/pam.d/common-session)" ] && echo "session required pam_limits.so" >> /etc/pam.d/common-session
sed -i '/^# End of file/,$d' /etc/security/limits.conf
cat >> /etc/security/limits.conf <<LIMITS_EOF
# End of file
*     soft   nofile    1048576
*     hard   nofile    1048576
*     soft   nproc     1048576
*     hard   nproc     1048576
*     soft   core      1048576
*     hard   core      1048576
*     hard   memlock   unlimited
*     soft   memlock   unlimited

root     soft   nofile    1048576
root     hard   nofile    1048576
root     soft   nproc     1048576
root     hard   nproc     1048576
root     soft   core      1048576
root     hard   core      1048576
root     hard   memlock   unlimited
root     soft   memlock   unlimited
LIMITS_EOF

sed -i '/fs.file-max/d' /etc/sysctl.conf
sed -i '/fs.inotify.max_user_instances/d' /etc/sysctl.conf
sed -i '/net.core.somaxconn/d' /etc/sysctl.conf
sed -i '/net.core.netdev_max_backlog/d' /etc/sysctl.conf
sed -i '/net.core.rmem_max/d' /etc/sysctl.conf
sed -i '/net.core.wmem_max/d' /etc/sysctl.conf
sed -i '/net.ipv4.udp_rmem_min/d' /etc/sysctl.conf
sed -i '/net.ipv4.udp_wmem_min/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_rmem/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_wmem/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_mem/d' /etc/sysctl.conf
sed -i '/net.ipv4.udp_mem/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_syncookies/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_fin_timeout/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_tw_reuse/d' /etc/sysctl.conf
sed -i '/net.ipv4.ip_local_port_range/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_max_syn_backlog/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_max_tw_buckets/d' /etc/sysctl.conf
sed -i '/net.ipv4.route.gc_timeout/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_syn_retries/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_synack_retries/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_timestamps/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_max_orphans/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_no_metrics_save/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_ecn/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_frto/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_mtu_probing/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_rfc1337/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_sack/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_fack/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_window_scaling/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_adv_win_scale/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_moderate_rcvbuf/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_keepalive_time/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_notsent_lowat/d' /etc/sysctl.conf
sed -i '/net.ipv4.conf.all.route_localnet/d' /etc/sysctl.conf
sed -i '/net.ipv4.ip_forward/d' /etc/sysctl.conf
sed -i '/net.ipv4.conf.all.forwarding/d' /etc/sysctl.conf
sed -i '/net.ipv4.conf.default.forwarding/d' /etc/sysctl.conf
sed -i '/net.core.default_qdisc/d' /etc/sysctl.conf
sed -i '/net.ipv4.tcp_congestion_control/d' /etc/sysctl.conf

cat >> /etc/sysctl.conf <<SYSCTL_EOF
fs.file-max = 1048576
fs.inotify.max_user_instances = 8192
net.core.somaxconn = 32768
net.core.netdev_max_backlog = 32768
net.core.rmem_max = 33554432
net.core.wmem_max = 33554432
net.ipv4.udp_rmem_min = 16384
net.ipv4.udp_wmem_min = 16384
net.ipv4.tcp_rmem = 4096 87380 33554432
net.ipv4.tcp_wmem = 4096 16384 33554432
net.ipv4.tcp_mem = 786432 1048576 26777216
net.ipv4.udp_mem = 65536 131072 262144
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_tw_reuse = 1
net.ipv4.ip_local_port_range = 1024 65000
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.route.gc_timeout = 100
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_synack_retries = 1
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_max_orphans = 131072
net.ipv4.tcp_no_metrics_save = 1
net.ipv4.tcp_ecn = 0
net.ipv4.tcp_frto = 0
net.ipv4.tcp_mtu_probing = 0
net.ipv4.tcp_rfc1337 = 0
net.ipv4.tcp_sack = 1
net.ipv4.tcp_fack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_adv_win_scale = 1
net.ipv4.tcp_moderate_rcvbuf = 1
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_notsent_lowat = 16384
net.ipv4.conf.all.route_localnet = 1
net.ipv4.ip_forward = 1
net.ipv4.conf.all.forwarding = 1
net.ipv4.conf.default.forwarding = 1
SYSCTL_EOF

modprobe tcp_bbr &>/dev/null

if grep -wq bbr /proc/sys/net/ipv4/tcp_available_congestion_control; then
    echo "net.core.default_qdisc = fq" >> /etc/sysctl.conf
    echo "net.ipv4.tcp_congestion_control = bbr" >> /etc/sysctl.conf
fi

sysctl -p && clear && . ~/.bashrc && echo "Successful kernel optimization - Powered by http://apad.pro"