Key and Value: DIRECTORY: /proc/sys/net/ipv4 ubuntu 10.10 64bit
nginx Mainly with load balancing and reverse proxy
Server will get more than 500 req/second


icmp_echo_ignore_all 0  
icmp_echo_ignore_broadcasts 1  
icmp_errors_use_inbound_ifaddr 0  
icmp_ignore_bogus_error_responses 1  
icmp_ratelimit 1000  
icmp_ratemask 6168  
igmp_max_memberships 20  
igmp_max_msf 10  
inet_peer_gc_maxtime 120  
inet_peer_gc_mintime 10  
inet_peer_maxttl 600  
inet_peer_minttl 120  
inet_peer_threshold 65664  
ip_default_ttl 64  
ip_dynaddr 0  
ip_forward 0  
ip_local_port_range 32768 61000 
ip_local_reserved_ports   
ip_no_pmtu_disc 0  
ip_nonlocal_bind 0  
ip_queue_maxlen 1024  
ipfrag_high_thresh 262144  
ipfrag_low_thresh 196608  
ipfrag_max_dist 64  
ipfrag_secret_interval 600  
ipfrag_time 30  
rt_cache_rebuild_count 4  
tcp_abc 0  
tcp_abort_on_overflow 0  
tcp_adv_win_scale 2  
tcp_allowed_congestion_control cubic reno  
tcp_app_win 31  
tcp_available_congestion_control cubic reno  
tcp_base_mss 512  
tcp_congestion_control cubic  
tcp_cookie_size 0  
tcp_dsack 1  
tcp_ecn 2  
tcp_fack 1  
tcp_fin_timeout 60  
tcp_frto 2  
tcp_frto_response 0  
tcp_keepalive_intvl 75  
tcp_keepalive_probes 9  
tcp_keepalive_time 7200  
tcp_low_latency 0  
tcp_max_orphans 65536  
tcp_max_ssthresh 0  
tcp_max_syn_backlog 1024  
tcp_max_tw_buckets 180000  
tcp_mem 191808 255744 383616
tcp_moderate_rcvbuf 1  
tcp_mtu_probing 0  
tcp_no_metrics_save 0  
tcp_orphan_retries 0  
tcp_reordering 3  
tcp_retrans_collapse 1  
tcp_retries1 3  
tcp_retries2 15  
tcp_rfc1337 0  
tcp_rmem 4096 87380 4194304
tcp_sack 1  
tcp_slow_start_after_idle 1  
tcp_stdurg 0  
tcp_syn_retries 5  
tcp_synack_retries 5  
tcp_syncookies 1  
tcp_thin_dupack 0  
tcp_thin_linear_timeouts 0  
tcp_timestamps 1  
tcp_tso_win_divisor 3  
tcp_tw_recycle 0  
tcp_tw_reuse 0  
tcp_window_scaling 1  
tcp_wmem 4096 16384 4194304
tcp_workaround_signed_windows 0  
udp_mem 191808 255744 383616
udp_rmem_min 4096  
udp_wmem_min 4096  
xfrm4_gc_thresh 524288