Category: computer networks

  • when RTO retransmissions remain unacknowledged…

    $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. […]

  • wireshark and micromuse-lm

    Frame 74388 (60 bytes on wire, 60 bytes captured) Ethernet II, Src: Netgear_b4:91:1a (00:1f:33:b4:91:1a), Dst: Giga-Byt_f2:71:b6 (00:1a:4d:f2:71:b6) Internet Protocol, Src: 209.85.231.100 (209.85.231.100), Dst: 10.0.0.2 (10.0.0.2) Transmission Control Protocol, Src Port: http (80), Dst Port: micromuse-lm (1534), Seq: 3405, Ack: 4005, Len: 0 Source port: http (80) Destination port: micromuse-lm (1534) Stream index: 222 Sequence number: […]

  • number of unacknowledged probes TCP

    tcp_keepalive_probes the number of unacknowledged probes to send before considering the connection dead and notifying the application layer source : www.tldp.org $cat /proc/sys/net/ipv4/tcp_keepalive_probes 9 $ trunk/os/ip/tcp.c – 7 identical 2436: /* Compute usable segment based on offered window and limit 2437: * window probes to one 2438: */ 3064: return tcphangup(c); 3065: if(n >= 1 […]

  • tcp tuning tcp_rfc1337

    From RFC 1337. TIME-WAIT state removes the hazard of old duplicates for “fast” or “long” connections, in which clock-driven ISN selection is unable to prevent overlap of the old and new sequence spaces. The TIME-WAIT delay allows all old duplicate segments time enough to die in the Internet before the connection is reopened. echo 1 […]

  • nc

    netcat is a simple unix utility which reads and writes data across network connections, using TCP or UDP protocol. netcat examples

  • nc – TCP/IP swiss army knife

    A UNIX Command Window I Server $nc -l -p 3333 hello hello how are you ? fine Window II client $nc 127.0.0.1 3333 hello hello how are you ? fine UNIX Explanation netcat is a simple unix utility which reads and writes data across network connections, using TCP or UDP protocol. Related Source Code Exposition […]

  • ypdomainname

    commands used to display or set domain name , hostname and YP domain name.