Sysctl Tweaks
Edit /etc/sysctl.conf
# vi /etc/sysctl.conf
Add the following items at the bottom.
# Controls the System Request debugging functionality of the kernel kernel.sysrq = 0 # Controls whether core dumps will append the PID to the core filename, usef$ kernel.core_uses_pid = 1 # Controls IP packet forwarding net.ipv4.ip_forward = 1 # Controls source route verification net.ipv4.conf.default.rp_filter = 1 # Do not accept source routing net.ipv4.conf.default.accept_source_route = 0 net.ipv4.conf.all.src_valid_mark=1 # Controls of how network trust neighbours (not!) net.ipv4.conf.all.secure_redirects = 0 net.ipv4.conf.all.accept_redirects = 0 net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.all.send_redirects = 0 # Controls the use of TCP syncookies net.ipv4.tcp_syncookies = 1 # Controls of syn backlog net.ipv4.tcp_max_syn_backlog = 4096 # Default ipv4 settings for usage on load balanced hosts. net.ipv4.conf.lo.arp_ignore = 1 net.ipv4.conf.lo.arp_announce = 2 net.ipv4.conf.all.arp_ignore = 1 net.ipv4.conf.all.arp_announce = 2 net.ipv4.tcp_mem = 786432 1048576 1572864 net.ipv4.tcp_tw_recycle = 1 # Default ipv4 connection tracking tweaks net.netfilter.nf_conntrack_tcp_timeout_syn_recv = 30 net.netfilter.nf_conntrack_tcp_timeout_time_wait = 60 net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 30 net.netfilter.nf_conntrack_tcp_timeout_close_wait = 30 net.netfilter.nf_conntrack_tcp_timeout_established = 600 net.netfilter.nf_conntrack_max = 1048576 # Disable ipv6 net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 # Disable ipv6 router advertisement addresses net.ipv6.conf.all.accept_ra = 0 net.ipv6.conf.ens192.accept_ra = 0 net.ipv6.conf.default.accept_ra = 0 # Disable ipv6 autoconfiguration net.ipv6.conf.all.autoconf = 0 net.ipv6.conf.ens192.autoconf = 0 net.ipv6.conf.default.autoconf = 0 kernel.shmmax = 2147483648 kernel.shmmni = 4096 kernel.sem = 250 32000 100 128 # TCP Performance tweaks net.ipv4.tcp_window_scaling = 1 net.ipv4.tcp_timestamps = 1 net.ipv4.tcp_syncookies = 1 net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.core.wmem_max = 4194304 ### IMPROVE SYSTEM MEMORY MANAGEMENT ### # Increase size of file handles and inode cache fs.file-max = 2097152 # Do less swapping vm.swappiness = 10 vm.dirty_ratio = 60 vm.dirty_background_ratio = 2 ### GENERAL NETWORK SECURITY OPTIONS ### # Number of times SYNACKs for passive TCP connection. net.ipv4.tcp_synack_retries = 2 # Allowed local port range net.ipv4.ip_local_port_range = 2000 65535 # Protect Against TCP Time-Wait net.ipv4.tcp_rfc1337 = 1 # Decrease the time default value for tcp_fin_timeout connection net.ipv4.tcp_fin_timeout = 15 # Decrease the time default value for connections to keep alive net.ipv4.tcp_keepalive_time = 300 net.ipv4.tcp_keepalive_probes = 5 net.ipv4.tcp_keepalive_intvl = 15 ### TUNING NETWORK PERFORMANCE ### # Default Socket Receive Buffer net.core.rmem_default = 31457280 # Maximum Socket Receive Buffer net.core.rmem_max = 12582912 # Default Socket Send Buffer net.core.wmem_default = 31457280 # Maximum Socket Send Buffer net.core.wmem_max = 12582912 # Increase number of incoming connections net.core.somaxconn = 4096 # Increase number of incoming connections backlog net.core.netdev_max_backlog = 65536 # Increase the maximum amount of option memory buffers net.core.optmem_max = 25165824 # Increase the maximum total buffer-space allocatable # This is measured in units of pages (4096 bytes) net.ipv4.tcp_mem = 65536 131072 262144 net.ipv4.udp_mem = 65536 131072 262144 # Increase the read-buffer space allocatable net.ipv4.tcp_rmem = 8192 87380 16777216 net.ipv4.udp_rmem_min = 16384 # Increase the write-buffer-space allocatable net.ipv4.tcp_wmem = 8192 65536 16777216 net.ipv4.udp_wmem_min = 16384 # Increase the tcp-time-wait buckets pool size to prevent simple DOS attacks net.ipv4.tcp_max_tw_buckets = 1440000 net.ipv4.tcp_tw_recycle = 1 net.ipv4.tcp_tw_reuse = 1 net.ipv4.tcp_low_latency = 1