加拿大华人论坛 加拿大百科There are several things you can do to prevent or mitigate the effects of a high rate



在加拿大


There are several things you can do to prevent or mitigate the effects of a high rate of packets, before you need to go out and buy any hardware upgrades. All of these are performed using FreeBSD's sysctl(8) command. Here are the settings you will need, you can place them in /etc/sysctl.conf:net.inet.tcp.msl=7500net.inet.tcp.msl defines the Maximum Segment Life. This is the maximum amount of time to wait for an ACK in reply to a SYN-ACK or FIN-ACK, in milliseconds. If an ACK is not received in this time, the segment can be considered "lost" and the network connection is freed.There are two implications for this. When you are trying to close a connection, if the final ACK is lost or delayed, the socket will still close, and more quickly. However if a client is trying to open a connection to you and their ACK is delayed more than 7500ms, the connection will not form. RFC 753 defines the MSL as 120 seconds (120000ms), however this was written in 1979 and timing issues have changed slightly since then. Today, FreeBSD's default is 30000ms. This is sufficient for most conditions, but for stronger DoS protection you will want to lower this to 7500, or maybe even less.net.inet.tcp.blackhole=2net.inet.tcp.blackhole defines what happens when a TCP packet is received on a closed port. When set to '1', SYN packets arriving on a closed port will be dropped without a RST packet being sent back. When set to '2', all packets arriving on a closed port are dropped without an RST being sent back. This saves both CPU time because packets don't need to be processed as much, and outbound bandwidth as packets are not sent out.net.inet.udp.blackhole=1net.inet.udp.blackhole is similar to net.inet.tcp.blackhole in its function. As the UDP protocol does not have states like TCP, there is only a need for one choice when it comes to dropping UDP packets. When net.inet.udp.blackhole is set to '1', all UDP packets arriving on a closed port will be dropped.net.inet.icmp.icmplim=50The name 'net.inet.icmp.icmplim' is somewhat misleading. This sysctl controls the maximum number of ICMP "Unreachable" and also TCP RST packets that will be sent back every second. It helps curb the effects of attacks which generate a lot of reply packets.kern.ipc.somaxconn=32768kern.ipc.somaxconn limits the maximum number of sockets that can be open at any one time. The default here is just 128. If an attacker can flood you with a sufficiently high number of SYN packets in a short enough period of time, all of your possible network connections will be used up, thus successfully denying your users access to the service.You may find these settings to either be too aggressive, or not aggressive enough. You should tune them until you receive satisfactory results.

  ·中文新闻 悉尼学生因佩戴巴勒斯坦围巾被禁止参加12年级正式课程
·中文新闻 二十年来,联邦政府一直向澳大利亚非法商人收取费用

加拿大百科-加拿大

不打游戏,我买了个游戏键盘

华人网原因无他,好键盘都是游戏键盘 我最基本的诉求是键帽字体清晰可见。我打字时虽然会盲打,但有些键还是要看的,例如数字/符号键、F功能键等。当把眼睛从屏幕转到键盘时,由于屏 ...

加拿大百科-加拿大

视频编辑器

华人网最近去百幕大,波士顿旅行,拍了不少视频。有的是用相机拍的,有的是用GoPro 拍的。想把这些视频根据日期,地点等加在一起。谷歌后发现微软Windows 11 带有 Clipchamp 这个视频编辑器, ...

加拿大百科-加拿大

开车的成本,我的10年Ford Edge

华人网我的福特开了10年,里程是85000公里,去养护时,问了一下这些年花费了多少维修费用?工作人员告诉我一共$4700,加上我前两年换了轮胎$1000,电池几百刀,合计6千多加元。在国内时我 ...

加拿大百科-加拿大

temu霸屏,怎么驱除?

华人网随便打开一个网页,发现temu的广告到处都是,上下左右,霸占了一大半面积,简直是强行抢占了别人的页面,非常离谱。我试图使用Google Report an ad/listing功能,填写Complaint on multiple ad ...

加拿大百科-加拿大

大家在拼多多上买东西了吗

华人网拼多多最近在加拿大开店了。 评论 拼多多app被Goolge下架了。Google suspends Chinas Pinduoduo app on security concernsAlphabet Incs Google suspended the Play version of PDD Holdings Incs Pinduoduo app for security concerns ...

加拿大百科-加拿大

请问抗焦虑症的替代药物

华人网家人在国内一直每天服用下面两种抗焦虑症的药,试过其他药都没有效果。准备回加拿大了,但是在加拿大的医保卡已经过期,另外不知道来加拿大有没有同样的替代药物?请问有没有 ...

加拿大百科-加拿大

亚马逊账号被黑记

华人网上来报个到,亚马逊账号被黑了,都不知道对方是怎么操作的...故事有点长,等有时间了再来更新。 评论 现在都有two step authentication,还能被黑,难道魔高一丈?最有效的解决途径是打 ...

加拿大百科-加拿大

大统华升职!!

华人网在大统华做supervisor要什么条件才可以升副主管,主管?薪水大约多少? 评论 大统华labor太卷了 评论 zxzwan2010 说:大统华labor太卷了点击展开...我问卷不卷了吗? 评论 赞!!! 太棒啦! ...

加拿大百科-加拿大

关于立遗书

华人网大家觉得有必要立遗嘱吗在安省 现在自住房想以后留给孩子独生子 评论 有比没有好, 没有的话万一有事真的很麻烦 评论 平安书有钱有业有孩子的必须做,如果大吉利是忽然走了,所 ...

加拿大百科-加拿大

世界十大最丑建筑。转帖

华人网互联网 榜首反而最具设计感? 评论 美学向来没有一定的準则,每个人的审美观各有不同,话虽如此,但当大多数人都认为一件事物是美或醜,总会有一定的参考价值。 评论 早前国外一 ...