BEAUTY AND PLAY
$cat /proc/sys/net/ipv4/tcp_orphan_retries 0 $ tcp_orphan_retries – INTEGER This value influences the timeout of a locally closed TCP connection, when RTO retransmissions remain unacknowledged. See tcp_retries2 for more details. The default value is 7 If your machine is a loaded WEB server, you should think about lowering this value, such sockets may consume significant resources. Cf. …
Continue reading “when RTO retransmissions remain unacknowledged…”
$cat /proc/sys/net/ipv4/tcp_no_metrics_save 0 $ tcp_no_metrics_save Normally, TCP will remember some characteristics about the last connection in the flow cache. If tcp_no_metrics_save is set, then it doesn’t. Useful for benchmarks or other tests. net/ipv4/sysctl_net_ipv4.c – 24 identical 452: { 453: .procname = “tcp_no_metrics_save”, 454: .data = &sysctl_tcp_nometrics_save, github.com/github/linux-2.6.git – GPL – C – More from linux-2.6.git …
Continue reading “characteristics about the last connection…”
$cat /proc/sys/net/ipv4/tcp_mtu_probing 0 $ tcp_mtu_probing – INTEGER Controls TCP Packetization-Layer Path MTU Discovery. Takes three values: 0 – Disabled 1 – Disabled by default, enabled when an ICMP black hole detected 2 – Always enabled, use initial MSS of tcp_base_mss. source : Linux kernel Documentation. 2.6.32 147: /* Black hole detection */ 148: tcp_mtu_probing(icsk, sk); …
$cat /proc/sys/net/ipv4/tcp_mem 40704 54272 81408 $ tcp_mem vector of 3 INTEGERs: min, pressure, max min: below this number of pages TCP is not bothered about its memory appetite. pressure: when amount of memory allocated by TCP exceeds this number of pages, TCP moderates its memory consumption and enters memory pressure mode, which is exited when …
$cat /proc/sys/net/ipv4/tcp_max_tw_buckets 180000 $ tcp_max_tw_buckets Maximal number of timewait sockets held by system simultaneously. If this number is exceeded time-wait socket is immediately destroyed and warning is printed. This limit exists only to prevent simple DoS attacks, you _must_ not lower the limit artificially, but rather increase it (probably, after increasing installed memory), if network …
$cat /proc/sys/net/ipv4/tcp_max_syn_backlog 1024 $ Maximal number of remembered connection requests, which still did not receive an acknowledgement from connecting client. The default value is 1024 for systems with more than 128 MB of memory, and 128 for low memory machines. If server suffers of overload, try to increase this number. source : http://www.linuxinsight.com/proc_sys_net_ipv4_tcp_max_syn_backlog.html Script.January/HPUX11/GEN003600 – …
Continue reading “remembered connection requests .. syn .. backlog”
$grep -r -l tcp_max * sysctl_net_ipv4.c tcp.c tcp_cong.c tcp_input.c tcp_output.c $ $grep -r -L tcp_max * af_inet.c ah4.c arp.c cipso_ipv4.c datagram.c devinet.c esp4.c fib_frontend.c fib_hash.c fib_lookup.h fib_rules.c fib_semantics.c fib_trie.c icmp.c igmp.c inet_connection_sock.c inet_diag.c inet_fragment.c inet_hashtables.c inet_lro.c inetpeer.c inet_timewait_sock.c ipcomp.c ipconfig.c ip_forward.c ip_fragment.c ip_gre.c ip_input.c ipip.c ipmr.c ip_options.c ip_output.c ip_sockglue.c Kconfig Makefile netfilter/ipt_ECN.c netfilter/nf_nat_amanda.c netfilter/nf_conntrack_l3proto_ipv4.c netfilter/nf_nat_proto_dccp.c …
Continue reading “grep … matches..and that not matches..-l.. -L”
$cat /proc/sys/net/ipv4/tcp_low_latency 0 $ tcp_low_latency – BOOLEAN If set, the TCP stack makes decisions that prefer lower latency as opposed to higher throughput. By default, this option is not set meaning that higher throughput is preferred. An example of an application where this default should be changed would be a Beowulf compute cluster. Default: 0 …
$cat /proc/sys/net/ipv4/tcp_keepalive_time 7200 $ tcp_keepalive_time the interval between the last data packet sent (simple ACKs are not considered data) and the first keepalive probe; after the connection is marked to need keepalive, this counter is not used any further source :http://tldp.org/HOWTO/TCP-Keepalive-HOWTO/usingkeepalive.html linux/net/ipv4/tcp.c – 8 identical 365: * TCP Keep-Alives (4.2.3.6) 366: * MAY provide keep-alives. …
Continue reading “the interval between the last data packet sent and…”
to match repetitions of a character a star is used. $cat samsung id proof license copy check leaf 1 $grep *p* samsung $grep p* samsung id proof license copy check leaf 1 $grep p samsung id proof license copy $grep *p samsung $grep * samsung Binary file PCBSD8.0-x86-bootonly.iso matches $grep “*” samsung $grep “p*” samsung …