ubuntu sysctl.conf settings

sysctl.conf

# changes from http://www.cyberciti.biz/faq/linux-kernel-etcsysctl-conf-security-hardening/

# Protect ICMP attacks
net.ipv4.icmp_echo_ignore_broadcasts = 1

# Turn on protection for bad icmp error messages
net.ipv4.icmp_ignore_bogus_error_responses = 1

# Turn on syncookies for SYN flood attack protection
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_synack_retries = 2

# Log suspcicious packets, such as spoofed, source-routed, and redirect
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1

# Disables these ipv4 features, not very legitimate uses
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0

# Enables RFC-reccomended source validation (dont use on a router)
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1

# Make sure no one can alter the routing tables
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.default.secure_redirects = 0

# Host only (we're not a router)
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0


# Turn on execshild
kernel.exec-shield = 1
kernel.randomize_va_space = 1

# Tune IPv6
# Number of Router Solicitations to send until assuming no routers are present.
# This is host and not router
net.ipv6.conf.default.router_solicitations = 0
# Accept Router Preference in RA?
net.ipv6.conf.default.accept_ra_rtr_pref = 0
# Learn Prefix Information in Router Advertisement
net.ipv6.conf.default.accept_ra_pinfo = 0
# Setting controls whether the system will accept Hop Limit settings from a router advertisement
net.ipv6.conf.default.accept_ra_defrtr = 0
#router advertisements can cause the system to assign a global unicast address to an interface
net.ipv6.conf.default.autoconf = 0
#how many neighbor solicitations to send out per address?
net.ipv6.conf.default.dad_transmits = 0
# How many global unicast IPv6 addresses can be assigned to each interface?
net.ipv6.conf.default.max_addresses = 1

# Optimization for port usefor LBs
# Increase system file descriptor limit
fs.file-max = 65535

# Allow for more PIDs (to reduce rollover problems); may break some programs 32768
kernel.pid_max = 65536

# Increase system IP port limits
net.ipv4.ip_local_port_range = 2000 65000

# Increase TCP max buffer size setable using setsockopt()
#net.ipv4.tcp_rmem = 4096 87380 8388608
#net.ipv4.tcp_wmem = 4096 87380 8388608

# Increase Linux auto tuning TCP buffer limits
# min, default, and max number of bytes to use
# set max to at least 4MB, or higher if you use very high BDP paths
#net.core.rmem_max = 8388608
#net.core.wmem_max = 8388608
#net.core.netdev_max_backlog = 5000
#net.ipv4.tcp_window_scaling = 1

# 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