Apr 7 2020 - What I did

本文回顾了计算机系统的基本组件,如程序计数器、指令寄存器等,对比了RISC与CISC架构的特点,介绍了防火墙中DMZ的概念,探讨了拒绝服务攻击的原理与方式,并深入讲解了软件开发中的合同、开发方法、内聚类型、中间代码的作用及形式,以及软件测试的不同阶段。此外,还涵盖了面向对象编程的特性与UML的基本元素。

what I reviewed

敲了个翻转2D-array和tree练练手

what I learned

  1. 【计算机系统】程序计数器、指令寄存器和指令译码器都是CPU中的。加法器是ALU的部件。
  2. 【计算机系统】RISC:精简,CISC:复杂。(见笔记p.1)
  3. 【防火墙】DMZ是非军事化区,在Internet和内部网络中间。
  4. 【拒绝服务攻击】
    DDoS:分布式拒绝服务
    目的:用户不能进入计算机网络系统或不能得到相应的服务的目的。
    方式:发送大量的干扰消息
  5. 【合同】委托开发软件著作权关系的建立,通常由委托方与受委托方订立合同而成立。(没合同就没得)
  6. 【结构化开发方法】自顶向下、逐层分解;原则:功能的分解与抽象;适用于数据处理领域;不是和解决大规模的、复杂的项目,难适应需求的变化。
  7. 【内聚类型】(看关键词)
    巧合内聚:没有任何联系
    逻辑内聚:逻辑相似
    时间内聚:需要同时执行
    通信内聚:使用相同的输入数据or产生相同的输出数据
    顺序内聚:顺序执行
    功能内聚:共同完成一个功能
  8. 【中间代码】
    目的:利于进行与机器无关的优化处理,提高编译程序的可移植性
    常用形式:逆波兰、四元、三元、树、图
  9. 【单缓冲】时间最长的俩*块数+最短的时间
  10. 【进程图】 复习
    手把手教你—进程资源分配
  11. 【CMM】软件过程能力成熟度模型,1级最低
  12. 【ISO/IEC9126】
    1层:质量特性
    2层:质量子特性
    3层:度量指标
    可靠性:成熟性、容错性、易恢复性
  13. *【软件测试】
    单元测试:软件实现阶段
    集成测试:系统和程序设计规格说明
    系统测试:需求规格说明(需求分析)
  14. 【面向对象】包含多态:子类型化
    对象通过消息传递的方式进行互相通信。
  15. 【UML】
    结构事物:静态部分,类、接口、协作、用例…
    行为事物:动态部分,交互、状态机、活动…
    分组事物:组织部分,包
# -- Rule engine initialization ---------------------------------------------- # Enable ModSecurity, attaching it to every transaction. Use detection # only to start with, because that minimises the chances of post-installation # disruption. # SecRuleEngine On Include /www/server/nginx/modsecurity/crs-setup.conf Include /www/server/nginx/modsecurity/rules/*.conf # 增加 PCRE 匹配限制 # -- Request body handling --------------------------------------------------- # Allow ModSecurity to access request bodies. If you don't, ModSecurity # won't be able to see any POST parameters, which opens a large security # hole for attackers to exploit. # SecRequestBodyAccess On # Enable XML request body parser. # Initiate XML Processor in case of xml content-type # SecRule REQUEST_HEADERS:Content-Type "^(?:application(?:/soap\+|/)|text/)xml" \ "id:'200000',phase:1,t:none,t:lowercase,pass,nolog,ctl:requestBodyProcessor=XML" # Enable JSON request body parser. # Initiate JSON Processor in case of JSON content-type; change accordingly # if your application does not use 'application/json' # SecRule REQUEST_HEADERS:Content-Type "^application/json" \ "id:'200001',phase:1,t:none,t:lowercase,pass,nolog,ctl:requestBodyProcessor=JSON" # Sample rule to enable JSON request body parser for more subtypes. # Uncomment or adapt this rule if you want to engage the JSON # Processor for "+json" subtypes # #SecRule REQUEST_HEADERS:Content-Type "^application/[a-z0-9.-]+[+]json" \ # "id:'200006',phase:1,t:none,t:lowercase,pass,nolog,ctl:requestBodyProcessor=JSON" # Maximum request body size we will accept for buffering. If you support # file uploads then the value given on the first line has to be as large # as the largest file you are willing to accept. The second value refers # to the size of data, with files excluded. You want to keep that value as # low as practical. # SecRequestBodyLimit 13107200 SecRequestBodyNoFilesLimit 131072 # What to do if the request body size is above our configured limit. # Keep in mind that this setting will automatically be set to ProcessPartial # when SecRuleEngine is set to DetectionOnly mode in order to minimize # disruptions when initially deploying ModSecurity. # SecRequestBodyLimitAction Reject # Maximum parsing depth allowed for JSON objects. You want to keep this # value as low as practical. # SecRequestBodyJsonDepthLimit 512 # Maximum number of args allowed per request. You want to keep this # value as low as practical. The value should match that in rule 200007. SecArgumentsLimit 1000 # If SecArgumentsLimit has been set, you probably want to reject any # request body that has only been partly parsed. The value used in this # rule should match what was used with SecArgumentsLimit SecRule &ARGS "@ge 1000" \ "id:'200007', phase:2,t:none,log,deny,status:400,msg:'Failed to fully parse request body due to large argument count',severity:2" # Verify that we've correctly processed the request body. # As a rule of thumb, when failing to process a request body # you should reject the request (when deployed in blocking mode) # or log a high-severity alert (when deployed in detection-only mode). # SecRule REQBODY_ERROR "!@eq 0" \ "id:'200002', phase:2,t:none,log,deny,status:400,msg:'Failed to parse request body.',logdata:'%{reqbody_error_msg}',severity:2" # By default be strict with what we accept in the multipart/form-data # request body. If the rule below proves to be too strict for your # environment consider changing it to detection-only. You are encouraged # _not_ to remove it altogether. # SecRule MULTIPART_STRICT_ERROR "!@eq 0" \ "id:'200003',phase:2,t:none,log,deny,status:400, \ msg:'Multipart request body failed strict validation: \ PE %{REQBODY_PROCESSOR_ERROR}, \ BQ %{MULTIPART_BOUNDARY_QUOTED}, \ BW %{MULTIPART_BOUNDARY_WHITESPACE}, \ DB %{MULTIPART_DATA_BEFORE}, \ DA %{MULTIPART_DATA_AFTER}, \ HF %{MULTIPART_HEADER_FOLDING}, \ LF %{MULTIPART_LF_LINE}, \ SM %{MULTIPART_MISSING_SEMICOLON}, \ IQ %{MULTIPART_INVALID_QUOTING}, \ IP %{MULTIPART_INVALID_PART}, \ IH %{MULTIPART_INVALID_HEADER_FOLDING}, \ FL %{MULTIPART_FILE_LIMIT_EXCEEDED}'" # Did we see anything that might be a boundary? # # Here is a short description about the ModSecurity Multipart parser: the # parser returns with value 0, if all "boundary-like" line matches with # the boundary string which given in MIME header. In any other cases it returns # with different value, eg. 1 or 2. # # The RFC 1341 descript the multipart content-type and its syntax must contains # only three mandatory lines (above the content): # * Content-Type: multipart/mixed; boundary=BOUNDARY_STRING # * --BOUNDARY_STRING # * --BOUNDARY_STRING-- # # First line indicates, that this is a multipart content, second shows that # here starts a part of the multipart content, third shows the end of content. # # If there are any other lines, which starts with "--", then it should be # another boundary id - or not. # # After 3.0.3, there are two kinds of types of boundary errors: strict and permissive. # # If multipart content contains the three necessary lines with correct order, but # there are one or more lines with "--", then parser returns with value 2 (non-zero). # # If some of the necessary lines (usually the start or end) misses, or the order # is wrong, then parser returns with value 1 (also a non-zero). # # You can choose, which one is what you need. The example below contains the # 'strict' mode, which means if there are any lines with start of "--", then # ModSecurity blocked the content. But the next, commented example contains # the 'permissive' mode, then you check only if the necessary lines exists in # correct order. Whit this, you can enable to upload PEM files (eg "----BEGIN.."), # or other text files, which contains eg. HTTP headers. # # The difference is only the operator - in strict mode (first) the content blocked # in case of any non-zero value. In permissive mode (second, commented) the # content blocked only if the value is explicit 1. If it 0 or 2, the content will # allowed. # # # See #1747 and #1924 for further information on the possible values for # MULTIPART_UNMATCHED_BOUNDARY. # SecRule MULTIPART_UNMATCHED_BOUNDARY "@eq 1" \ "id:'200004',phase:2,t:none,log,deny,msg:'Multipart parser detected a possible unmatched boundary.'" # PCRE Tuning # We want to avoid a potential RegEx DoS condition # SecPcreMatchLimit 1000000 SecPcreMatchLimitRecursion 1000000 # Some internal errors will set flags in TX and we will need to look for these. # All of these are prefixed with "MSC_". The following flags currently exist: # # MSC_PCRE_LIMITS_EXCEEDED: PCRE match limits were exceeded. # SecRule TX:/^MSC_/ "!@streq 0" \ "id:'200005',phase:2,t:none,deny,msg:'ModSecurity internal error flagged: %{MATCHED_VAR_NAME}'" # -- Response body handling -------------------------------------------------- # Allow ModSecurity to access response bodies. # You should have this directive enabled in order to identify errors # and data leakage issues. # # Do keep in mind that enabling this directive does increases both # memory consumption and response latency. # SecResponseBodyAccess On # Which response MIME types do you want to inspect? You should adjust the # configuration below to catch documents but avoid static files # (e.g., images and archives). # SecResponseBodyMimeType text/plain text/html text/xml # Buffer response bodies of up to 512 KB in length. SecResponseBodyLimit 524288 # What happens when we encounter a response body larger than the configured # limit? By default, we process what we have and let the rest through. # That's somewhat less secure, but does not break any legitimate pages. # SecResponseBodyLimitAction ProcessPartial # -- Filesystem configuration ------------------------------------------------ # The location where ModSecurity stores temporary files (for example, when # it needs to handle a file upload that is larger than the configured limit). # # This default setting is chosen due to all systems have /tmp available however, # this is less than ideal. It is recommended that you specify a location that's private. # SecTmpDir /tmp/ # The location where ModSecurity will keep its persistent data. This default setting # is chosen due to all systems have /tmp available however, it # too should be updated to a place that other users can't access. # SecDataDir /tmp/ # -- File uploads handling configuration ------------------------------------- # The location where ModSecurity stores intercepted uploaded files. This # location must be private to ModSecurity. You don't want other users on # the server to access the files, do you? # #SecUploadDir /opt/modsecurity/var/upload/ # By default, only keep the files that were determined to be unusual # in some way (by an external inspection script). For this to work you # will also need at least one file inspection rule. # #SecUploadKeepFiles RelevantOnly # Uploaded files are by default created with permissions that do not allow # any other user to access them. You may need to relax that if you want to # interface ModSecurity to an external program (e.g., an anti-virus). # #SecUploadFileMode 0600 # -- Debug log configuration ------------------------------------------------- # The default debug log configuration is to duplicate the error, warning # and notice messages from the error log. # #SecDebugLog /opt/modsecurity/var/log/debug.log #SecDebugLogLevel 3 # -- Audit log configuration ------------------------------------------------- # Log the transactions that are marked by a rule, as well as those that # trigger a server error (determined by a 5xx or 4xx, excluding 404, # level response status codes). # SecAuditEngine RelevantOnly SecAuditLogRelevantStatus "^(?:5|4(?!04))" # Log everything we know about a transaction. SecAuditLogParts ABIJDEFHZ # Use a single file for logging. This is much easier to look at, but # assumes that you will use the audit log only ocassionally. # SecAuditLogType Serial SecAuditLog /var/log/modsec_audit.log # Specify the path for concurrent audit logging. #SecAuditLogStorageDir /opt/modsecurity/var/audit/ # -- Miscellaneous ----------------------------------------------------------- # Use the most commonly used application/x-www-form-urlencoded parameter # separator. There's probably only one application somewhere that uses # something else so don't expect to change this value. # SecArgumentSeparator & # Settle on version 0 (zero) cookies, as that is what most applications # use. Using an incorrect cookie version may open your installation to # evasion attacks (against the rules that examine named cookies). # SecCookieFormat 0 # Specify your Unicode Code Point. # This mapping is used by the t:urlDecodeUni transformation function # to properly map encoded data to your language. Properly setting # these directives helps to reduce false positives and negatives. # SecUnicodeMapFile unicode.mapping 20127 # Improve the quality of ModSecurity by sharing information about your # current ModSecurity version and dependencies versions. # The following information will be shared: ModSecurity version, # Web Server version, APR version, PCRE version, Lua version, Libxml2 # version, Anonymous unique id for host. SecStatusEngine On 这个配置文件中,有开放别的服务器去访问吗
06-25
I am unable to try/install Ubuntu 22.04 using USB. I use the guideline provided by Ubuntu official website, the USB installer is created using balenaEtcher. I try to boot using the way provided by Lenovo official website (restart and press F12 while having USB plugged in). My laptop is Lenovo 310-14IKB Laptop (ideapad) - Type 80TU, Windows 10. I tried turning off fast startup/ changing boot mode to legacy/changing boot priority from UEFI to legacy/disabling safe booting mode, but none of them works. lenovousb-installation Share Improve this question Follow edited Oct 17, 2022 at 18:03 Pablo Bianchi's user avatar Pablo Bianchi 17.6k55 gold badges9191 silver badges129129 bronze badges asked Apr 30, 2022 at 9:08 Keus's user avatar Keus 9111 gold badge11 silver badge55 bronze badges 2 Please edit your original question to tell us more: Did you check the sha256sum of the iso file (that it was downloaded correctly)? What tool did you use to create the USB installer drive? How did you try to boot into the USB drive? - I see 'noveau' in the output list. It indicates that there is an nvidia graphics chip/card, and I suggest that you try booting with the boot option nomodeset. There is detailed help about it at this link. If that works, you can install a proprietary nvidia graphics driver later on. – sudodus CommentedApr 30, 2022 at 9:21 2 Your edits to the original question indicate that you are doing things correctly. You might check the sha256sum too (check versus the published value), but I am more convinced now, that you have a graphics problem, so please try booting with nomodeset (or simply select 'Ubuntu (safe graphics)' in the grub menu. – sudodus CommentedApr 30, 2022 at 10:03 If still no luck, we need new ideas to test, for example, have you tested with the previous but still supported LTS version Ubuntu 20.04.4? – sudodus CommentedApr 30, 2022 at 10:15 Thank you everyone!!!!!!! I made it! – Keus CommentedApr 30, 2022 at 12:06 Congratulations, and welcome back, if you have other questions in the future :-) – sudodus CommentedApr 30, 2022 at 12:26 Show 1 more comment 4 Answers Sorted by: Highest score (default) 4 Hope my little experience can help anyone using Lenovo laptop in future. I change to using Rufus to create the USB using the GPT option. I disabled the fast startup option but didn't disable the safe booting option. Then I boot the laptop using NOVO button (option 2 in Lenovo official guidelines) instead of using legacy bootmode. And lastly add in the nomodeset option Share Improve this answer Follow answered Apr 30, 2022 at 12:16 Keus's user avatar Keus 9111 gold badge11 silver badge55 bronze badges I have Dell Latitude E6530. I followed using Rufus v 3.20, GPT partition scheme, UEFI (non CSM) target system. Then, boot in UEFI mode (safe graphics) option. And finally! No black screen and I can progress the Ubuntu 22.04 installation. – Joshua T CommentedOct 5, 2022 at 13:32 Add a comment 2 dont use Try install bla bla use Safe GUI bla bla Share Improve this answer Follow answered Aug 17, 2023 at 5:46 Jonry Simbolon's user avatar Jonry Simbolon 2111 bronze badge Add a comment 2 My computer use RTX3090 and RTX2080, show the message the same. I selected Safe Graphic, it worked fine. Share Improve this answer Follow answered Jul 20, 2024 at 12:42 John's user avatar John 2122 bronze badges That was already said in the answers. You have added noting new. Sorry not an answer. – David DE CommentedJul 20, 2024 at 13:44 Add a comment 0 I was firing the USB from terminal command line and I was getting this error. When I switched to BalenaEtcher, in addition to change the USB port and sticker. it worked like a charm!详细解释一下
10-11
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