EC2 sysctl.conf

gistfile1.txt

# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
# sysctl.conf(5) for more details.

#
# Network settings
#
#
# This sets the max OS receive buffer size for all types of connections
net.core.rmem_max = 33554432
# This sets the max OS send buffer size for all types of connections.
net.core.wmem_max = 33554432
# Increase number of incoming connections backlog
net.core.netdev_max_backlog = 3000
# TCP Autotuning setting.
# The first value tells the kernel the minimum receive buffer for each TCP connection, and this buffer
# is always allocated to a TCP socket, even under high pressure on the system.
# The second value specified tells the kernel the default receive buffer allocated for each TCP socket.
# This value overrides the /proc/sys/net/core/rmem_default value used by other protocols.
# The third and last value specified in this variable specifies the maximum receive buffer that can be allocated for a TCP socket.
net.ipv4.tcp_rmem = 4096 16384 33554432
# TCP Autotuning setting.
# This variable takes 3 different values which holds information on how much TCP sendbuffer memory
# space each TCP socket has to use. Every TCP socket has this much buffer space to use before the buffer
# is filled up. Each of the three values are used under different conditions.
# The first value in this variable tells the minimum TCP send buffer space available for a single TCP socket.
# The second value in the variable tells us the default buffer space allowed for a single TCP socket to use.
# The third value tells the kernel the maximum TCP send buffer space.
net.ipv4.tcp_wmem=  4096 16384 33554432
# TCP Autotuning setting.
# The tcp_mem variable defines how the TCP stack should behave when it comes to memory usage.
# The first value specified in the tcp_mem variable tells the kernel the low threshold. Below this point,
# the TCP stack do not bother at all about putting any pressure on the memory usage by different TCP sockets.
# The second value tells the kernel at which point to start pressuring memory usage down.
# The final value tells the kernel how many memory pages it may use maximally.
# If this value is reached, TCP streams and packets start getting dropped until we reach a lower memory
# usage again. This value includes all TCP sockets currently in use.
net.ipv4.tcp_mem = 786432 1048576 26777216

# Increase the tcp-time-wait buckets pool size to prevent simple DOS attacks
net.ipv4.tcp_max_tw_buckets = 360000
net.ipv4.tcp_tw_reuse = 1

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 1
# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0

# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 1
# Allowed local port range
net.ipv4.ip_local_port_range = 1024 65535
net.ipv4.tcp_timewait_len = 20
net.ipv4.tcp_fin_timeout = 20

#
# Kernel settings
#

# 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

#
# Message queue settings
#

# Controls the default maxmimum size of a mesage queue
kernel.msgmnb = 65536
# Controls the maximum size of a message, in bytes
kernel.msgmax = 65536

#
# Shared memory settings
#

# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736
# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296

#
# Filesystem settings
#

# Increase size of file handles and inode cache
fs.file-max = 400000