practice of system and network administration

Log System Common logs are typically stored in/var/log: You can roughly divide the logs into two categories based on the service object: System log, Application log. System log is mainly for the system built-in program or system kernel such as log information such as

system on the network, any destruction behavior is found in time, reduce the possible loss to the smallest; Finally, the internal personnel (controllable user) to establish an audit system, "To ungrateful, conceal", forensics can enhance the deterrent effect of security. After a year of practice testing, "vase" model

20155324 "Network countermeasure Technology" Web Security Foundation Practice Experiment ContentUse Webgoat for XSS attacks, CSRF attacks, SQL injectionExperimental question and answer SQL injection attack principle, how to defendThe ①sql injection attack is an attacker who adds additional SQL statements at the end of a predefined query in a Web application, takes SQL statements as user names, and then ente

Java is doing well in network programming. The main purpose of java is to create a network. It can easily access resources on the network. This section describes two network communication mechanisms: URL communication and Socket communication.URL indicates the reference or address of a resource on the Internet. Java

if it fails, returns Invalid_socket. The first parameter of the function specifies a stream socket in the listening state; the operating system uses the second parameter to return the address structure of the newly created socket, and the operating system uses the third parameter to return the length of the address structure of the newly created socket. The following is an example of a call to accept:struc

reliability for LANs. For example, the video conferencing system, does not require audio and video data is absolutely correct, as long as the consistency can be guaranteed, in this case, it is obvious that using UDP is more reasonable.third, what is the socketSockets are also commonly referred to as "sockets," which describe IP addresses and ports, and are a handle to a communication chain. The two programs on the

The previous note mainly introduced the basic knowledge related to time_wait. This article describes how to solve the problem raised by the article title based on practice. 1. view the system network configuration and current TCP statusIt is necessary to understand the default network configuration of the

?command line Input nslookup, and then enter your URL, if the normal display IP address, then DNS is correct, otherwise DNS failure.3. About the Hosts fileWhen a computer accesses a website, the DNS server first resolves the network domain name to an IP address, so that our computer can access it. If each domain name request waits for the domain name server to be resolved and returns the IP, the access speed will be slower, and the hosts file can solv

by the application layer of the other system. For example, a PC program communicates with another computer, where one computer uses an extended 210 binary interchange (EBCDIC), and the other uses the U.S. Information Interchange Standard Code (ASCII) to represent the same characters. If necessary, the presentation layer enables conversion between multiple data formats by using a pass-through format. 7. Application layer: The OSI layer closest to the

Article title: ADSL dual-network card Internet sharing practice under RedHat7.2. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. In the previous section, I applied to activate the monthly subscription ADSL service at China Net

Article Title: RedHatLinux network server architecture practice (1 ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. Preface 　　 Here I will explain the motivation, purpose, content, principles and usage of this document. 　　 I

The main purpose of the script is to practice capturing signals in a Linux bash script, by practicing the use of functions, and by terminating a running program, subsequent processing of files opened by the program, and so on!Scripting Features:Ping IP within a network segment, detect which IP is online, which IP is not onlinecommand to Practice:1, MktempUsage: #

The main purpose of the script is to practice capturing signals in a Linux bash script, by practicing the use of functions, and by terminating a running program, subsequent processing of files opened by the program, and so on!Scripting Features:Ping IP within a network segment, detect which IP is online, which IP is not onlinecommand to Practice:1, MktempUsage: #

[] args) { //create Httpclientbuilder httpclientbuilder Httpclientbuilder = Httpclientbuilder. Create(); //HttpClient closeablehttpclient closeablehttpclient = httpclientbuilder. Build (); //proxy address, proxy port number, protocol type httphost Proxy = new httphost ("127.0.0.1", 8118, "http"); requestconfig Config = requestconfig. Custom(). SetProxy (proxy). Build (); //Request address httpget HttpPost = new httpget ("http://mobil7rab6nuf7vx.onion/"); httppost. Setconfig (config); try {c

" three books to choose, combined with their own understanding of these times, through the GNS3 to build the relevant network environment to carry out the relevant agreement analysis, I believe this will definitely be a very good experience!When I was writing these posts, I was in the reality of my personal device, The operating system environment used (including the operating

return 0; the}G. Flood problemsTime limit: C/s 1 sec, other languages 2 secondsSpace limitations: C/C + + 32768K, other languages 65536K64bit IO Format:%lldLinks: Https://www.nowcoder.com/acm/contest/75/GSource: Cow Network topic Description Give a number n, ask 1 to N, how many number is not a multiple of 2 5 11 13. Input Description:There are multiple sets of inputsOne number per line n,1Output Description:The output output of each row is not a

XSS attack, how to Defend Principle: The main purpose of XSS attack is to find a way to obtain the target attack website cookie, because the cookie is equivalent to seesion, with this information can be in any PC can access the Internet access to the website, and the other People's Health landing, do some damage. Defense: When a malicious code value is displayed as the content of a tag: HTML tags and some special characters (" When malicious code is displayed a

)). Start (); } }} class userloginthread implements Runnable{ PrivateSocket s; Userloginthread (Socket s) { This. s=s; } Public voidRun () {Try{BufferedReader burin=NewBufferedReader (NewInputStreamReader (S.getinputstream ())); for(intI=0;i3; i++) {String user=burin.readline (); System.out.println ("username sent to:"+user);if(user==NULL) {System.out.println ("is empty"+user); Break; } BufferedReader bur=NewBufferedReader (NewFileReader ("User.txt")); String line=NULL;Booleanflag=false; w

Article Title: RedHatLinux network server architecture practice (4 ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. 4. Reload the dynamic library # Because we use the custom compilation and installation method, it is differe

Article Title: RedHatLinux network server architecture practice (9 ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. Common error 4: Invalid authorization specification 　　 500 Servlet Exception Java. SQL. SQLException: Invali