Update linux-kernel-sysctl-hardening.md

linux-kernel-sysctl-hardening.md

@@ -6,8 +6,6 @@
 - [Documentation](#documentation)
 - [Disclaimer](#disclaimer)
 - [Keys](#keys)
-  - [Table View](#table-view)
-  - [Flat File View](#flat-file-view)
 
 ## Overview
 
@@ -28,27 +26,44 @@ I do not know what most of these settings do. This list is being provided just a
 
 ## Keys
 
-### Table View
-
 |`key=value`|Note|[Documentation|
 |--|--|--|
 |`fs.file-max = 65535`||[/sysctl/fs.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/fs.txt)|
 |`fs.protected_hardlinks = 1`||[/sysctl/fs.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/fs.txt)|
 |`fs.protected_symlinks = 1`||[/sysctl/fs.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/fs.txt)|
+|`fs.suid_dumpable = 0`||[/sysctl/fs.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/fs.txt)|
 |`kernel.core_uses_pid = 1`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
 |`kernel.ctrl-alt-del = 0`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
 |`kernel.kptr_restrict = 2`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
-|`kernel.pid_max = 65536`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
+|`kernel.maps_protect = 1`|||
+|`kernel.msgmax = 65535`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
+|`kernel.msgmnb = 65535`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
+|`kernel.pid_max = 65535`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
 |`kernel.randomize_va_space = 2`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
+|`kernel.shmall = 268435456`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
+|`kernel.shmmax = 268435456`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
 |`kernel.sysrq = 0`||[/sysctl/kernel.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt)|
+|`net.core.default_qdisc = fq`||[/sysctl/net.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/net.txt)|
+|`net.core.dev_weight = 64`||[/sysctl/net.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/net.txt)|
+|`net.core.netdev_max_backlog = 16384`||[/sysctl/net.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/net.txt)|
+|`net.core.optmem_max = 65535`||[/sysctl/net.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/net.txt)|
+|`net.core.rmem_default = 262144`||[/sysctl/net.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/net.txt)|
+|`net.core.rmem_max = 16777216`||[/sysctl/net.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/net.txt)|
+|`net.core.somaxconn = 32768`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.core.wmem_default = 262144`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.core.wmem_max = 16777216`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.all.accept_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.all.accept_source_route = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.conf.all.bootp_relay = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.conf.all.forwarding = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.all.log_martians = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.conf.all.proxy_arp = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.all.rp_filter = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.all.secure_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.all.send_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.default.accept_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.default.accept_source_route = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.conf.default.forwarding = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.default.log_martians = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.default.rp_filter = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.conf.default.secure_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
@@ -66,134 +81,71 @@ I do not know what most of these settings do. This list is being provided just a
 |`net.ipv4.icmp_ignore_bogus_error_responses = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.ip_forward = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.ip_local_port_range = 2000 65000`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.ipfrag_high_thresh = 262144`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.ipfrag_low_thresh = 196608`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.neigh.default.gc_interval = 30`|||
+|`net.ipv4.neigh.default.gc_thresh1 = 32`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.neigh.default.gc_thresh2 = 1024`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.neigh.default.gc_thresh3 = 2048`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.neigh.default.proxy_qlen = 96`|||
+|`net.ipv4.neigh.default.unres_qlen = 6`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.route.flush = 1`|||
+|`net.ipv4.tcp_congestion_control = htcp`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_ecn = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_fastopen = 3`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_fin_timeout = 15`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_keepalive_intvl = 15`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_keepalive_probes = 5`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_keepalive_time = 1800`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_max_orphans = 16384`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_max_syn_backlog = 2048`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_max_tw_buckets = 1440000`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_moderate_rcvbuf = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_no_metrics_save = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_orphan_retries = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_reordering = 3`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_retries1 = 3`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_retries2 = 15`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_rfc1337 = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_rmem = 8192 87380 16777216`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_sack = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_slow_start_after_idle = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_syn_retries = 5`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_synack_retries = 2`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_syncookies = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-|`net.ipv4.tcp_timestamps = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_timestamps = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_tw_recycle = 0`|||
+|`net.ipv4.tcp_tw_reuse = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv4.tcp_window_scaling = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.tcp_wmem = 8192 65536 16777216`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.udp_rmem_min = 16384`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv4.udp_wmem_min = 16384`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv6.conf.all.accept_ra=0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.all.accept_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.all.accept_source_route = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv6.conf.all.autoconf = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv6.conf.all.forwarding = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.accept_ra_defrtr = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.accept_ra_pinfo = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.accept_ra_rtr_pref = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv6.conf.default.accept_ra=0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.accept_redirects = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.accept_source_route = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.autoconf = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.dad_transmits = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
+|`net.ipv6.conf.default.forwarding = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.max_addresses = 1`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
 |`net.ipv6.conf.default.router_solicitations = 0`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-
+|`net.ipv6.conf.eth0.accept_ra=0`|change `eth0` to your network interface|[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-### Flat File View
+|`net.ipv6.conf.eth0.autoconf = 0`|change `eth0` to your network interface|[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-
+|`net.ipv6.ip6frag_high_thresh = 262144`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-    ###
+|`net.ipv6.ip6frag_low_thresh = 196608`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-    # start from https://github.com/imthenachoman/How-To-Secure-A-Linux-Server/
+|`net.ipv6.route.flush = 1`|||
-    ###
+|`net.unix.max_dgram_qlen = 50`||[/networking/ip-sysctl.txt](https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt)|
-    
+|`vm.dirty_background_ratio = 5`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-    ###
+|`vm.dirty_ratio = 30`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-    # start fs
+|`vm.min_free_kbytes = 65535`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-    # https://github.com/torvalds/linux/blob/master/Documentation/sysctl/fs.txt
+|`vm.mmap_min_addr = 4096`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-    ###
+|`vm.overcommit_memory = 0`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-
+|`vm.overcommit_ratio = 50`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-    fs.file-max = 65535
+|`vm.swappiness = 30`||[/sysctl/vm.txt](https://github.com/torvalds/linux/blob/master/Documentation/sysctl/vm.txt)|
-    fs.protected_hardlinks = 1
-    fs.protected_symlinks = 1
-
-    ###
-    # end fs
-    ###
-
-    ###
-    # start kernel
-    # https://github.com/torvalds/linux/blob/master/Documentation/sysctl/kernel.txt
-    ###
-
-    kernel.core_uses_pid = 1
-    kernel.ctrl-alt-del = 0
-    kernel.kptr_restrict = 2
-    kernel.pid_max = 65536
-    kernel.randomize_va_space = 2
-    kernel.sysrq = 0
-
-    ###
-    # end kernel
-    ###
-
-    ###
-    # start net
-    # https://github.com/torvalds/linux/blob/master/Documentation/networking/ip-sysctl.txt
-    ###
-
-    net.ipv4.conf.all.accept_redirects = 0
-    net.ipv4.conf.all.accept_source_route = 0
-    net.ipv4.conf.all.log_martians = 1
-    net.ipv4.conf.all.rp_filter = 1
-    net.ipv4.conf.all.secure_redirects = 0
-    net.ipv4.conf.all.send_redirects = 0
-    net.ipv4.conf.default.accept_redirects = 0
-    net.ipv4.conf.default.accept_source_route = 0
-    net.ipv4.conf.default.log_martians = 1
-    net.ipv4.conf.default.rp_filter = 1
-    net.ipv4.conf.default.secure_redirects = 0
-    net.ipv4.conf.default.send_redirects = 0
-
-    ##
-    # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-    # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-    # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-    #
-    # remember to change eth0 to your network interface
-    #
-    # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-    # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-    # !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-    ##
-    net.ipv4.conf.eth0.accept_redirects = 0
-    net.ipv4.conf.eth0.accept_source_route = 0
-    net.ipv4.conf.eth0.log_martians = 0
-    net.ipv4.conf.eth0.rp_filter = 1
-
-    net.ipv4.conf.lo.accept_redirects = 0
-    net.ipv4.conf.lo.accept_source_route = 0
-    net.ipv4.conf.lo.log_martians = 0
-    net.ipv4.conf.lo.rp_filter = 1
-    net.ipv4.icmp_echo_ignore_all = 1
-    net.ipv4.icmp_echo_ignore_broadcasts = 1
-    net.ipv4.icmp_ignore_bogus_error_responses = 1
-    net.ipv4.ip_forward = 0
-    net.ipv4.ip_local_port_range = 2000 65000
-    net.ipv4.tcp_fin_timeout = 15
-    net.ipv4.tcp_keepalive_time = 1800
-    net.ipv4.tcp_max_syn_backlog = 2048
-    net.ipv4.tcp_max_tw_buckets = 1440000
-    net.ipv4.tcp_rfc1337 = 1
-    net.ipv4.tcp_sack = 0
-    net.ipv4.tcp_syn_retries = 5
-    net.ipv4.tcp_synack_retries = 2
-    net.ipv4.tcp_syncookies = 1
-    net.ipv4.tcp_timestamps = 0
-    net.ipv4.tcp_window_scaling = 0
-    net.ipv6.conf.all.accept_redirects = 0
-    net.ipv6.conf.all.accept_source_route = 0
-    net.ipv6.conf.default.accept_ra_defrtr = 0
-    net.ipv6.conf.default.accept_ra_pinfo = 0
-    net.ipv6.conf.default.accept_ra_rtr_pref = 0
-    net.ipv6.conf.default.accept_redirects = 0
-    net.ipv6.conf.default.accept_source_route = 0
-    net.ipv6.conf.default.autoconf = 0
-    net.ipv6.conf.default.dad_transmits = 0
-    net.ipv6.conf.default.max_addresses = 1
-    net.ipv6.conf.default.router_solicitations = 0
-
-    ###
-    # end kernel
-    ###
-    
-    ###
-    # end from https://github.com/imthenachoman/How-To-Secure-A-Linux-Server/
-    ###