115 lines
4.0 KiB
Plaintext
115 lines
4.0 KiB
Plaintext
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#
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# /etc/sysctl.conf - Configuration file for setting system variables
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# See /etc/sysctl.d/ for additional system variables
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# See sysctl.conf (5) for information.
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#
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#kernel.domainname = example.com
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# Uncomment the following to stop low-level messages on console
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#kernel.printk = 3 4 1 3
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##############################################################3
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# Functions previously found in netbase
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#
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# Uncomment the next two lines to enable Spoof protection (reverse-path filter)
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# Turn on Source Address Verification in all interfaces to
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# prevent some spoofing attacks
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#net.ipv4.conf.default.rp_filter=1
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#net.ipv4.conf.all.rp_filter=1
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# Uncomment the next line to enable TCP/IP SYN cookies
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# See http://lwn.net/Articles/277146/
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# Note: This may impact IPv6 TCP sessions too
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#net.ipv4.tcp_syncookies=1
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# Uncomment the next line to enable packet forwarding for IPv4
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#net.ipv4.ip_forward=1
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# Uncomment the next line to enable packet forwarding for IPv6
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# Enabling this option disables Stateless Address Autoconfiguration
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# based on Router Advertisements for this host
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#net.ipv6.conf.all.forwarding=1
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###################################################################
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# Additional settings - these settings can improve the network
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# security of the host and prevent against some network attacks
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# including spoofing attacks and man in the middle attacks through
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# redirection. Some network environments, however, require that these
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# settings are disabled so review and enable them as needed.
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#
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# Do not accept ICMP redirects (prevent MITM attacks)
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#net.ipv4.conf.all.accept_redirects = 0
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#net.ipv6.conf.all.accept_redirects = 0
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# _or_
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# Accept ICMP redirects only for gateways listed in our default
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# gateway list (enabled by default)
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# net.ipv4.conf.all.secure_redirects = 1
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#
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# Do not send ICMP redirects (we are not a router)
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#net.ipv4.conf.all.send_redirects = 0
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#
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# Do not accept IP source route packets (we are not a router)
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#net.ipv4.conf.all.accept_source_route = 0
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#net.ipv6.conf.all.accept_source_route = 0
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#
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# Log Martian Packets
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#net.ipv4.conf.all.log_martians = 1
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#
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# CIS Benchmark Adjustments
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# See: https://github.com/alanorth/securekickstarts
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kernel.randomize_va_space = 2
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net.ipv4.ip_forward = 0
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net.ipv4.conf.all.send_redirects = 0
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net.ipv4.conf.default.send_redirects = 0
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net.ipv4.conf.all.accept_source_route = 0
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net.ipv4.conf.default.accept_source_route = 0
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net.ipv4.conf.all.accept_redirects = 0
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net.ipv4.conf.default.accept_redirects = 0
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net.ipv4.conf.all.secure_redirects = 0
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net.ipv4.conf.default.secure_redirects = 0
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net.ipv4.conf.all.log_martians = 1
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net.ipv4.conf.default.log_martians = 1
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net.ipv4.icmp_echo_ignore_broadcasts = 1
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net.ipv4.icmp_ignore_bogus_error_responses = 1
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net.ipv4.conf.all.rp_filter = 1
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net.ipv4.conf.default.rp_filter = 1
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net.ipv4.tcp_syncookies = 1
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# TCP stuff
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# See: http://fasterdata.es.net/host-tuning/linux/
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# increase TCP max buffer size settable using setsockopt()
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net.core.rmem_max = 16777216
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net.core.wmem_max = 16777216
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# increase Linux autotuning TCP buffer limit
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net.ipv4.tcp_rmem = 4096 87380 16777216
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net.ipv4.tcp_wmem = 4096 65536 16777216
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# increase the length of the processor input queue
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net.core.netdev_max_backlog = 30000
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{# kernels after 2.6.32 don't have buggy cubic #}
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{% if ansible_kernel < "2.6.33" %}
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# recommended default congestion control is htcp
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net.ipv4.tcp_congestion_control=htcp
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{% endif %}
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# recommended for hosts with jumbo frames enabled
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#net.ipv4.tcp_mtu_probing=1
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{# disable iptables on bridge interfaces on VM hosts #}
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{% if ansible_virtualization_role == "host" %}
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net.bridge.bridge-nf-call-ip6tables = 0
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net.bridge.bridge-nf-call-iptables = 0
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net.bridge.bridge-nf-call-arptables = 0
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{% endif %}
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{% if 'web' in group_names %}
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# increase quadruplets (src ip, src port, dest ip, dest port)
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# see: http://vincent.bernat.im/en/blog/2014-tcp-time-wait-state-linux.html
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net.ipv4.ip_local_port_range = 10240 65535
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# recommended for web servers, especially if running SPDY
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# see: http://www.chromium.org/spdy/spdy-best-practices
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net.ipv4.tcp_slow_start_after_idle = 0
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{% endif %}
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