Comment 23 for bug 447197

i have same problem, and i have a upgrade my ubuntu from 9.04, also i have changed /etc/sysctl.conf
in ubuntu 9.04

i have resolved this problem after i change this file to

<code>
#
# /etc/sysctl.conf - Configuration file for setting system variables
# See sysctl.conf (5) for information.
#

#kernel.domainname = example.com
#net/ipv4/icmp_echo_ignore_broadcasts=1

# Uncomment the following to stop low-level messages on console
#kernel.printk = 4 4 1 7

##############################################################3
# Functions previously found in netbase
#

# Uncomment the next two lines to enable Spoof protection (reverse-path filter)
# Turn on Source Address Verification in all interfaces to
# prevent some spoofing attacks
#net.ipv4.conf.default.rp_filter=1
#net.ipv4.conf.all.rp_filter=1

# Uncomment the next line to enable TCP/IP SYN cookies
#net.ipv4.tcp_syncookies=1

# Uncomment the next line to enable packet forwarding for IPv4
#net.ipv4.ip_forward=1

# Uncomment the next line to enable packet forwarding for IPv6
#net.ipv6.ip_forward=1

###################################################################
# Additional settings - these settings can improve the network
# security of the host and prevent against some network attacks
# including spoofing attacks and man in the middle attacks through
# redirection. Some network environments, however, require that these
# settings are disabled so review and enable them as needed.
#
# Ignore ICMP broadcasts
#net/ipv4/icmp_echo_ignore_broadcasts = 1
#
# Ignore bogus ICMP errors
#net/ipv4/icmp_ignore_bogus_error_responses = 1
#
# Do not accept ICMP redirects (prevent MITM attacks)
#net/ipv4/conf/all/accept_redirects = 0
# _or_
# Accept ICMP redirects only for gateways listed in our default
# gateway list (enabled by default)
# net/ipv4/conf/all/secure_redirects = 1
#
# Do not send ICMP redirects (we are not a router)
#net/ipv4/conf/all/send_redirects = 0
#
# Do not accept IP source route packets (we are not a router)
#net/ipv4/conf/all/accept_source_route = 0
#
# Enable TCP Syn Cookies
#net/ipv4/tcp_syncookies = 1
#
# Log Martian Packets
#net/ipv4/conf/all/log_martians = 1
#
# Always defragment packets
#net/ipv4/ip_always_defrag = 1
</code>

i took this from http://ubuntuforums.org/showthread.php?t=597831