System default cause dropped packets

[Navraj Chohan]

When running ab tool the following error shows up:
apr_socket_recv: Connection timed out (110)

And in /var/log/kern.log you'll see:
nf_conntrack: table full, dropping packet.

To increase the values:
In /etc/sysctl.conf add the following two lines
net.core.somaxconn = 10240
net.netfilter.nf_conntrack_max = 262144

and then run
/sbin/sysctl -p /etc/sysctl.conf

[kylea (kylea)]

I am getting a similar result - depending upon the value of -c, 100 is ok 200 will throw the timeout

ab -n 200000 -c 100 -k "http://192.168.100.10/test2.php" >> OK
ab -n 200000 -c 200 -k "http://192.168.100.10/test2.php" >> timeout

here are some values from /etc/sysctl.conf

net.ipv4.ip_forward = 1
kernel.shmmax = 2208845824
kernel.shmall = 2208845824
net.ipv4.tcp_tw_reuse = 1
net.ipv4.netfilter.ip_conntrack_max = 131072
net.ipv4.tcp_tw_recycle = 0
net.ipv4.tcp_orphan_retries = 1
net.ipv4.tcp_fin_timeout = 25
net.ipv4.tcp_max_orphans = 262144
net.ipv4.ip_local_port_range = 32768 61000
net.netfilter.nf_conntrack_max = 262144
net.core.somaxconn = 65536

Environment: Ubuntu Server 12.04 x86_64 running the web server and Ubuntu Server 10.04 x86_64 running the ab command. The Ubuntu Server 12.04 x86_64 is running inside a KVM virtual machine