I'm following a security guide(http://www.thefanclub.co.za/how-to/how-secure-ubuntu-1204-lts-server-part-1-basics) to strengthen my OpenVZ based VPS webserver running Ubuntu 12.04 , a part of that asks to make some modifications to sysctl.conf. But I am not sure if all that really makes sense in an openVZ container, as it is a shared kernel.
Here are the edits that are suggested for sysctl.conf
# IP Spoofing protection net.ipv4.conf.all.rp_filter = 1 net.ipv4.conf.default.rp_filter = 1 # Ignore ICMP broadcast requests net.ipv4.icmp_echo_ignore_broadcasts = 1 # Disable source packet routing net.ipv4.conf.all.accept_source_route = 0 net.ipv6.conf.all.accept_source_route = 0 net.ipv4.conf.default.accept_source_route = 0 net.ipv6.conf.default.accept_source_route = 0 # Ignore send redirects net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.default.send_redirects = 0 # Block SYN attacks net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_max_syn_backlog = 2048 net.ipv4.tcp_synack_retries = 2 net.ipv4.tcp_syn_retries = 5 # Log Martians net.ipv4.conf.all.log_martians = 1 net.ipv4.icmp_ignore_bogus_error_responses = 1 # Ignore ICMP redirects net.ipv4.conf.all.accept_redirects = 0 net.ipv6.conf.all.accept_redirects = 0 net.ipv4.conf.default.accept_redirects = 0 net.ipv6.conf.default.accept_redirects = 0 # Ignore Directed pings net.ipv4.icmp_echo_ignore_all = 1
When I tried to test these with my OpenVZ container I got permission denied for 3 of these entries which probably have been locked down by my host.
error: permission denied on key 'net.ipv4.tcp_max_syn_backlog' error: permission denied on key 'net.ipv4.tcp_synack_retries' error: permission denied on key 'net.ipv4.tcp_syn_retries'
Now my question is: Does it really make sense to include these to my sysctl.conf in an openVZ container environment ? I want to tighten security on my server but I am not really sure if they would take effect in my openVZ container.