预备 首先提及一个概念叫重放攻击,对应的机制叫做:anti-replay https://en.wikipedia.org/wiki/Anti-replay IPsec协议的anti-replay特性就是用来应对重放攻击的一种机制,方法是: 增加两个机制:序列号(seqence number)和收包窗口(sliding window) 发包方从0开始计数,每发一个包就把序号加1. 收包方拥有一个长度为N的滑动窗口,序号在窗口外的包都认为是无效包. 序号在窗口内的重复包,也被认为是无效包.窗口下边…

原文见:http://packetlife.net/blog/2010/jun/7/understanding-tcp-sequence-acknowledgment-numbers/ from:https://blog.csdn.net/a19881029/article/details/38091243 如果你正在读这篇文章,很可能你对TCP“非著名”的“三次握手”或者说“SYN,SYN/ACK,ACK”已经很熟悉了.不幸的是,对很多人来说,对TCP的学习就仅限于此了.尽管年代久远,TCP仍…

点击阅读原译文 原文见:http://packetlife.net/blog/2010/jun/7/understanding-tcp-sequence-acknowledgment-numbers/ 如果你正在读这篇文章,很可能你对TCP"非著名"的"三次握手"或者说"SYN,SYN/ACK,ACK"已经很熟悉了.不幸的是,对很多人来说,对TCP的学习就仅限于此了.尽管年代久远,TCP仍是一个相当复杂并且值得研究的协议.这篇文章的目的是让你能够…

mysql oom之后,重启时发生130517 16:00:10 InnoDB: Error: page 447 log sequence number 292344272InnoDB: is in the future! Current system log sequence number 1595916.InnoDB: Your database may be corrupt or you may have copied the InnoDBInnoDB: tablespace but no…

1570: Sequence Number 时间限制: 1 Sec  内存限制: 1280 MB 题目描述 In Linear algebra, we have learned the definition of inversion number: Assuming A is a ordered set with n numbers ( n > 1 ) which are different from each other. If exist positive integers i , j, (…

InnoDB: The log sequence number in ibdata files does not matchInnoDB的:在ibdata文件的日志序列号不匹配 可能ibdata文件损坏了解决办法如下:在my.cny 的[mysqld]中加入 # Size of each log file in a log group. You should set the combined size      # of log files to about 25%-100% of your b…

G. Sequence Number In Linear algebra, we have learned the definition of inversion number: Assuming A is a ordered set with n numbers ( n > 1 ) which are different from each other. If exist positive integers i , j, ( 1 ≤ i < j ≤ n and A[i] > A[j])…

有时候,你会在ORACLE数据库的告警日志中发现"Thread <number> cannot allocate new log, sequence <number>  Checkpoint not complete"这类告警.具体案例如下所示: Thread 1 cannot allocate new log, sequence 279334 Checkpoint not complete Current log# 4 seq# 279333 mem# 0:…

当插入值需要从另外一张表中检索得到的时候,如下语法的sql语句已经不能完成该功能:insert into my_table(id, name) values ((select seq_my_table.nextval from dual), ‘runto30′); 会报“ORA-02287: sequence number not allowed here”的错误,可以使用如下语句来完成: insert into my_table(id, name) select seq_my_table.ne…

Python之路迭代器协议.for循环机制.三元运算.列表解析式.生成器 一.迭代器协议 a迭代的含义 迭代器即迭代的工具,那什么是迭代呢? #迭代是一个重复的过程,每次重复即一次迭代,并且每次迭代的结果都是下一次迭代的初始值 b为何要有迭代器? 对于序列类型:字符串.列表.元组,我们可以使用索引的方式迭代取出其包含的元素.但对于字典.集合.文件等类型是没有索引的,若还想取出其内部包含的元素,则必须找出一种不依赖于索引的迭代方式,这就是迭代器 c可迭代对象 可迭代对象指的是内置有iter方法的对…