Not sure where I got these, but might be useful. Also points to https://gist.github.com/kgriffs/4027835. Just not to forget to add all these settings in freshly spawned AWS instances:

# Assumes a beefy machine with lots of network bandwidth # Protection from SYN flood attack. net.ipv4.tcp_syncookies = 1 # See evil packets in your logs. net.ipv4.conf.all.log_martians = 1 # Enable source validation by reversed path, as specified in RFC1812 net.ipv4.conf.all.rp_filter = 1 # Ignore all ICMP ECHO and TIMESTAMP requests sent to it via broadcast/multicast net.ipv4.icmp_echo_ignore_broadcasts = 1 net.ipv4.icmp_ignore_bogus_error_responses = 1 # Discourage Linux from swapping idle server processes to disk (default = 60) vm.swappiness = 1 # Be less aggressive about reclaiming cached directory and inode objects # in order to improve filesystem performance. vm.vfs_cache_pressure = 50 # Tweak how the flow of kernel messages is throttled. #kernel.printk_ratelimit_burst = 10 #kernel.printk_ratelimit = 5 # Increase system file descriptor limit so we will (probably) # never run out under lots of concurrent requests. # (Per-process limit is set in /etc/security/limits.conf) fs.file-max = 184028 # Widen the port range used for outgoing connections net.ipv4.ip_local_port_range = 10000 65000 # If your servers talk UDP, also up these limits #net.ipv4.udp_rmem_min = 8192 #net.ipv4.udp_wmem_min = 8192 # -------------------------------------------------------------------- # The following help the server efficiently pipe large amounts of data # -------------------------------------------------------------------- # Disable source routing and redirects net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.all.accept_redirects = 0 net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.all.secure_redirects = 0 # Disable packet forwarding. net.ipv4.ip_forward = 0 net.ipv6.conf.all.forwarding = 0 # Disable TCP slow start on idle connections net.ipv4.tcp_slow_start_after_idle = 0 # Increase Linux autotuning TCP buffer limits # Set max to 16MB for 1GE and 32M (33554432) or 54M (56623104) for 10GE # Don't set tcp_mem itself! Let the kernel scale it based on RAM. net.core.rmem_max = 16777216 net.core.wmem_max = 16777216 net.core.rmem_default = 16777216 net.core.wmem_default = 16777216 net.core.optmem_max = 40960 net.ipv4.tcp_rmem = 4096 87380 16777216 net.ipv4.tcp_wmem = 4096 65536 16777216 # Enable BBR; requires Linux kernel version 4.9 or higher net.core.default_qdisc=fq net.ipv4.tcp_congestion_control=bbr # -------------------------------------------------------------------- # The following allow the server to handle lots of connection churn # -------------------------------------------------------------------- # Disconnect dead TCP connections after 1 minute net.ipv4.tcp_keepalive_time = 60 # Wait a maximum of 5 * 2 = 10 seconds in the TIME_WAIT state after a FIN, to handle # any remaining packets in the network. # net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait = 5 net.netfilter.nf_conntrack_tcp_timeout_time_wait = 5 # Allow a high number of timewait sockets net.ipv4.tcp_max_tw_buckets = 40960 # Timeout broken connections faster (amount of time to wait for FIN) net.ipv4.tcp_fin_timeout = 10 # Let the networking stack reuse TIME_WAIT connections when it thinks it's safe to do so net.ipv4.tcp_tw_reuse = 1 # Determines the wait time between isAlive interval probes (reduce from 75 sec to 15) net.ipv4.tcp_keepalive_intvl = 15 # Determines the number of probes before timing out (reduce from 9 sec to 5 sec) net.ipv4.tcp_keepalive_probes = 5 # -------------------------------------------------------------------- # The following optimize connection setup # -------------------------------------------------------------------- net.ipv4.tcp_fastopen = 3 # -------------------------------------------------------------------- # The following allow the server to handle lots of connection requests # -------------------------------------------------------------------- net.ipv4.tcp_max_syn_backlog = 100000 net.core.somaxconn = 50000 net.core.netdev_max_backlog = 100000