tcp supplement

header_len = struct.unpack (' i ', PHONE.RECV (4)) [0] #吧bytes类型的反解 #在收报头 header_bytes = phone.recv (header_len) #收过来的也是bytes类型 header_ JSON = Header_bytes.decode (' utf-8 ') #拿到json格式的字典 header_dic = json.loads (Header_json) #反序列化拿到字典了 total_size = header_dic[' total_size '] #就拿到数据的总长度了 #最后收数据 recv_size = 0 total_data=b " While recv_size　　Five, struct module#该模块可以把一个类型, such as numbers, to a fixed-length bytes type import structres = Struct.pack (' i ', 12345

. If the initialization succeeds, it is necessary to proceed with the next initialization if (self = [super init]) {//Initialize success ; } return Self ;//3. Returns a value that has already been initialized}3. Custom Construction methodsSome specifications of the L-structure method -(ID) initwithage: (int) Age { if "self = [super init]") {= age ; } return Self ;}Pass multiple parameters for initialization-(ID) initwithage: (int) Age Andno: (int)

Oracle Import and Export File supplement, oracle Import and Export supplement In the past two days, oracle has imported and exported table data. 1. oracle provides three ways to Import and export files. (1) Oracle export/import (2) slq export/Import (3) PL/SQL export and import The second method is suitable for the import and export of one or more tables, with a small amount of data imported and exported. I

Linux scheduled task supplement and Linux task supplement Scheduled task instances Example 1: print your name to the "/server/log/file named after your name" every minute. [Root @ chengliang log] # mkdir-p/server/log/[root @ chengliang log] # echo "chensiqi">/server/log/chengliang [root @ chengliang log] # crontab-l # time sync by zcl at least /5/8 */5 *****/usr/sbin/ntpdate time.nist.gov>/dev/null 2> 1 [r

'}]For row in result:Print (row) #获取queryset中的字典数据类型.About Values_list:result = models. User.objects,all (). Values_list (' username ', ' password ')#生成一个queryset数据类型, but this query results only username columns and password columns, except that the Ganso type is stored in Queryset.# queryset[(' username ', ' xxx '), (' Password ', ' xxx ')]！！ How do I cross tables when using values and values_list?Double-underline _ _ Cross-table forward lookup:res = models. User.object.all (). VALUES (' id '

Linux terminal and command supplement, Linux terminal command supplementWhoami: print a valid user IDWho: displays which users are logged on to the systemWho-r displays the running levelWho-H display field nameW: Show who has logged on and what are they doingLast: the/var/log/wtmp file is displayed. The user logon history and system restart history are displayed.-N #: displays the latest # related informationLastb:/var/tmp/btmp, displays the user's wr

Turn from:Http://blog.chinaunix.net/uid-9112803-id-3212041.htmlSummary:In this paper, we briefly introduce the theory of TCP-oriented connection, describe the meanings of each field of TCP messages, and select TCP connections from Wireshark capture packet to establish the relevant message segment.I. OverviewTCP is a reliable connection-oriented transport protocol

system_u:object_r:oracle_port_t:s0 portcon tcp 2484 system_u:object_r:oracle_port_t:s0 portcon tcp 5432 system_u:object_r:postgresql_port_t:s0> sepolicy network -t postgresql_port_tpostgresql_port_t: tcp: 5432Boolean Httpd_can_network_connect> sesearch -A -s httpd_t -b httpd_can_network_connect -p name_connectFound 1 semantic av rules: allow httpd_t port

This title uses two Don's and three names. It is actually the same thing, but there are different sayings on the Internet, in addition, it seems that some people call TCP drilling. (My friend Niu asked me, "Do you want to punch the hole? Would you like to help me borrow an electric drill?" "~! · ￥ % ...... ·!"). Let's take a look at the technical background: The rapid development of the Internet and the limit on the number of IPv4 addresses make Netwo

Application Layer Protocol Transport Layer Protocol Port HTTP Tcp 80 Ftp Tcp 21 and 20 Telnet Tcp 23 Smtp Tcp 25 POP3 Tcp 110

the SYN message is changed to 1, and the serial number seq is randomly generated as x, and the client enters the syn_sent state. 2, second handshake Server side from the closed state to open into the listen listening state, when the client sends a SYN message, send the syn+ack message, the SEQ and ACK flag in the message is replaced by 1, and the last serial number seq is a random y, The acknowledgment number ACK is the client serial number x+1, and the server side enters the SYN_RCVD state.

First, TCP Commonly used port scanning methods are the following three: 1.connect scanning We know that the common TCP socket implementation process is The more essential connection and end process is the following: From the above two figures we can see that the target host of a port if the monitoring state (listening or linsten), then when I connect the target host can be successful, otherwise the port is

TCP has a total of four main timers. As mentioned above, a timeout timer is the most complex one in TCP, and the other three are: Stick to Timer Active Timer 2msl Timer The persistence timer is used to prevent the two sides from waiting for deadlocks after the announcement window is 0, while the persistence timer is used to process semi-open connections.1. Stick to the timer It is simple to stick to th

Introduction to tcp protocol (TCP/IP) and TCP/IP Role of the transport layer: the IP layer provides point-to-point connections, and the transport layer provides end-to-end connections. Transport Layer Protocol 1. TCP (Transmission Control Protocol) Transmission Control Protocol Reliable and connection-oriented pro

After writing the topic just think of one thing, if the phone as a client (not connected to the case of the router), the wireless Phone connection module will assign an IP address,,, this IP address in advance I do not know .... I'll see if there's an instruction in the AT command that prints the IP address of the device after connecting to its own WiFi signal.I can't find ......... .......OK, I connect directly with the phone, look at the IP address assigned by the phone, and then set up the mo

This title uses two comma three names, actually said is the same thing, but the internet has a different version of it, and also seems to have someone called TCP drilling (my friend, I heard after the girl asked "to punch Ah, or I help you to borrow an electric drill to come?" "" ~! ￥%......! ”）。 Gossip Less, we first look at the technical background: The rapid development of the Internet and the limitation of the number of IPV4 addresses make netwo

TCP/IP details -- Role of the TCP Header option field -- TCP Header1. Set the option field of the TCP header to 40B and write down some common items:2. The Option END field (EOP, 0x00) occupies 1B, and only one packet segment is used once. It is placed at the end to indicate that there are no more messages in the heade

design based on components, in fact, the MySQL architecture is neither strictly component-based nor truly modular. In a strict sense, the MySQL system integrates code based on function libraries and data structures.MySQL subsystem and core libraryMySQL contains the following subsystems and core libraries:--Network connection and Network Communication protocol subsystem (TCP/IP protocol, which provides read and write parsing and sending of packets to

Client: Using system;Using system. Collections. Generic;Using system. componentmodel;Using system. Data;Using system. drawing;Using system. text;Using system. Windows. forms;Using system. net. Sockets;Using system. net;Using system. Threading; Namespace mytcpchat{Public partial class form1: Form{Private thread th;Socket C;Public form1 (){Initializecomponent ();Control. checkforillegalcrossthreadcils = false;} Private void form1_load (Object sender, eventargs E){ }Public void client (){Try{Ipend

The content of this article UDP protocol Sockets How to open a process Multi-process implementation of concurrent socket communication Join method Daemon process Sync Lock Process queue Producer Consumer Model Process Pool Paramiko Module One, the UDP protocol socket1.TCP and UDP differ in the transport layer:UDP is a non-connected, unreliable datagram protocol. TC