Initial commit.

sysctl.conf.old-2020-10-20-17_37_02

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+# sysctl settings are defined through files in
+# /usr/lib/sysctl.d/, /run/sysctl.d/, and /etc/sysctl.d/.
+#
+# Vendors settings live in /usr/lib/sysctl.d/.
+# To override a whole file, create a new file with the same in
+# /etc/sysctl.d/ and put new settings there. To override
+# only specific settings, add a file with a lexically later
+# name in /etc/sysctl.d/ and put new settings there.
+#
+# For more information, see sysctl.conf(5) and sysctl.d(5).
+
+### GENERAL SYSTEM SECURITY OPTIONS ###
+
+# Kernel settings
+kernel.printk = 4 4 1 7
+kernel.panic = 10
+kernel.hung_task_panic = 1
+kernel.nmi_watchdog = 0
+kernel.core_pattern = /var/crash/core.%e.pid_%p.uid_%u.sig_%s
+
+# Controls the System Request debugging functionality of the kernel
+kernel.sysrq = 0
+
+# Controls whether core dumps will append the PID to the core filename.
+# Useful for debugging multi-threaded applications.
+kernel.core_uses_pid = 1
+
+# Allow for more PIDs
+kernel.pid_max = 65535
+
+# Enable ExecShield protection
+kernel.randomize_va_space = 2
+
+# Controls the maximum size of a message, in bytes
+kernel.msgmnb = 65536
+
+# Controls the default maxmimum size of a mesage queue
+kernel.msgmax = 65536
+
+# Restrict core dumps
+fs.suid_dumpable = 0
+
+# Hide exposed kernel pointers
+kernel.kptr_restrict = 1
+
+### KERNEL FINE TUNNING ###
+kernel.sem = 250 256000 64 512
+
+# Configure Kernel Parameter for Accepting ICMP Redirects By Default
+net.ipv4.conf.all.accept_redirects = 0
+net.ipv4.conf.default.accept_redirects = 0
+
+# Disable Kernel Parameter for Sending ICMP Redirects for All Interfaces
+net.ipv4.conf.all.send_redirects= 0
+net.ipv4.conf.default.send_redirects = 0
+
+# Ensure ICMP redirects are not accepted
+net.ipv4.conf.all.secure_redirects = 0
+net.ipv4.conf.default.secure_redirects = 0
+
+# Enable ip forwarding
+net.ipv4.ip_forward = 1
+
+# Enable IP spoofing protection
+net.ipv4.conf.all.rp_filter = 1
+net.ipv4.conf.default.rp_filter = 1
+
+# Ensure source routed packets are not accepted
+net.ipv4.conf.all.accept_source_route = 0
+net.ipv4.conf.default.accept_source_route = 0
+
+# Ignoring broadcasts request
+net.ipv4.icmp_echo_ignore_broadcasts=1
+#net.ipv4.icmp_ignore_bogus_error_messages=1
+
+# Make sure spoofed packets get logged
+net.ipv4.conf.all.log_martians = 0
+
+# nginx
+
+# recycle Zombie connections
+#net.inet.tcp.fast_finwait2_recycle = 1
+#net.inet.tcp.maxtcptw = 200000
+
+# increase number of files
+#kern.maxfiles = 65535
+#kern.maxfilesperproc = 16384
+
+net.ipv4.tcp_fin_timeout = 30
+net.ipv4.ip_local_port_range = 1024 65023
+
+# Increase size of file handles and inode cache
+fs.file-max = 2097152
+
+# do less swapping
+vm.swappiness = 10
+vm.dirty_background_ratio = 1
+vm.dirty_ratio = 1
+vm.dirty_background_bytes = 5
+vm.dirty_bytes = 0
+vm.dirty_writeback_centisecs = 500
+vm.dirty_expire_centisecs = 3000
+vm.vfs_cache_pressure = 50
+
+# specifies the minimum virtual address that a process is allowed to mmap
+vm.mmap_min_addr = 4096
+
+# Set maximum amount of memory allocated to shm to 256MB
+kernel.shmmax = 268435456
+kernel.shmall = 268435456
+
+# Keep at least 64MB of free RAM space available
+vm.min_free_kbytes = 65535
+
+# Prevent SYN attack, enable SYNcookies (they will kick-in when the max_syn_backlog reached)
+net.ipv4.tcp_syncookies = 1
+net.ipv4.tcp_syn_retries = 2
+net.ipv4.tcp_synack_retries = 2
+
+# increase socket listen backlog
+net.core.somaxconn = 32768
+net.ipv4.tcp_max_tw_buckets = 1440000
+
+# number of packets to keep in backlog before the kernel starts dropping them
+net.ipv4.tcp_max_syn_backlog = 65535
+
+# 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 = 10
+net.ipv4.tcp_keepalive_intvl = 30
+
+# Don't relay bootp
+net.ipv4.conf.all.bootp_relay = 0
+
+# Don't proxy arp for anyone
+net.ipv4.conf.all.proxy_arp = 0
+
+# Turn on the tcp_timestamps, accurate timestamp make TCP congestion control algorithms work better
+net.ipv4.tcp_timestamps = 1
+
+# Don't ignore directed pings
+net.ipv4.icmp_echo_ignore_all = 0
+
+# Enable ignoring broadcasts request
+net.ipv4.icmp_echo_ignore_broadcasts = 1
+
+# Enable bad error message Protection
+#net.ipv4.icmp_ignore_bogus_error_responses = 1
+
+# Enable a fix for RFC1337 - time-wait assassination hazards in TCP
+net.ipv4.tcp_rfc1337 = 1
+#net.inet.tcp.delayed_ack = 0
+#net.inet.tcp.restrict_rst = 1
+
+### TUNING NETWORK PERFORMANCE ###
+
+# For high-bandwidth low-latency networks, use 'htcp' congestion control
+# Do a 'modprobe tcp_htcp' first
+#net.ipv4.tcp_congestion_control = htcp
+
+# Turn on the tcp_window_scaling
+net.ipv4.tcp_window_scaling = 1
+
+# Increase the read-buffer space allocatable
+net.ipv4.tcp_rmem = 8192 87380 16777216
+net.ipv4.udp_rmem_min = 16384
+net.core.rmem_default = 8388608
+net.core.rmem_max = 16777216
+
+# Increase the write-buffer-space allocatable
+net.ipv4.tcp_wmem = 8192 65536 16777216
+net.ipv4.udp_wmem_min = 16384
+net.core.wmem_default = 8388608
+net.core.wmem_max = 16777216
+
+# Increase number of incoming connections
+net.ipv4.tcp_max_tw_buckets = 1440000
+
+# Increase number of incoming connections backlog
+net.core.netdev_max_backlog = 16384
+net.core.dev_weight = 64
+
+# Increase the maximum amount of option memory buffers
+net.core.optmem_max = 25165824
+
+# Limit number of orphans, each orphan can eat up to 16M (max wmem) of unswappable memory
+net.ipv4.tcp_max_orphans = 262144
+net.ipv4.tcp_orphan_retries = 0
+
+# Increase the maximum memory used to reassemble IP fragments
+net.ipv4.ipfrag_high_thresh = 512000
+net.ipv4.ipfrag_low_thresh = 446464
+
+# don't cache ssthresh from previous connection
+net.ipv4.tcp_no_metrics_save = 1
+net.ipv4.tcp_moderate_rcvbuf = 1
+
+# Increase size of RPC datagram queue length
+net.unix.max_dgram_qlen = 50
+
+# Don't allow the arp table to become bigger than this
+net.ipv4.neigh.default.gc_thresh3 = 2048
+
+# Tell the gc when to become aggressive with arp table cleaning.
+# Adjust this based on size of the LAN. 1024 is suitable for most /24 networks
+net.ipv4.neigh.default.gc_thresh2 = 1024
+
+# Adjust where the gc will leave arp table alone - set to 32.
+net.ipv4.neigh.default.gc_thresh1 = 32
+
+# Adjust to arp table gc to clean-up more often
+net.ipv4.neigh.default.gc_interval = 30
+
+# Increase TCP queue length
+net.ipv4.neigh.default.proxy_qlen = 96
+net.ipv4.neigh.default.unres_qlen = 6
+net.ipv4.ip_nonlocal_bind = 1
+net.ipv4.tcp_abort_on_overflow = 0
+
+# Enable Explicit Congestion Notification (RFC 3168), disable it if it doesn't work for you
+net.ipv4.tcp_ecn = 2
+net.ipv4.tcp_reordering = 3
+
+# How many times to retry killing an alive TCP connection
+net.ipv4.tcp_retries2 = 15
+net.ipv4.tcp_retries1 = 3
+
+# Avoid falling back to slow start after a connection goes idle
+# keeps our cwnd large with the keep alive connections (kernel > 3.6)
+net.ipv4.tcp_slow_start_after_idle = 0
+
+# This will enusre that immediatly subsequent connections use the new values
+net.ipv4.route.flush = 1
+net.ipv6.route.flush = 1
+
+# mitigate against buffer overflows
+#kernel.exec-shield = 1
+kernel.randomize_va_space = 2
+
+# maximum number of allowable concurrent requests (default 64K)
+#fs.aio-max-nr = 1048576
+
+vm.max_map_count = 262144
+vm.overcommit_memory = 1
+
+# congestion control (kernel 4.x)
+#net.ipv4.tcp_ecn = 2
+#net.core.default_qdisc=fq
+#net.ipv4.tcp_congestion_control=bbr
+