解惑 » Linux http://www.jiehoo.me 解己之惑，解人之惑 Sun, 07 Mar 2010 13:28:16 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 mod_rewrite规则是有顺序的 http://www.jiehoo.me/mod_rewrite%e8%a7%84%e5%88%99%e6%98%af%e6%9c%89%e9%a1%ba%e5%ba%8f%e7%9a%84.htm http://www.jiehoo.me/mod_rewrite%e8%a7%84%e5%88%99%e6%98%af%e6%9c%89%e9%a1%ba%e5%ba%8f%e7%9a%84.htm#comments Thu, 29 Mar 2007 12:56:23 +0000 Cherami http://www.jiehoo.com/mod_rewrite%e8%a7%84%e5%88%99%e6%98%af%e6%9c%89%e9%a1%ba%e5%ba%8f%e7%9a%84.htm 原来曾经写过一个有关JR的PR的值的问题，今天littlebat留言说明了原因，使用301永久重定向就可以解决，当然马上试了下，但是遇到一个问题，例如我访问http://jiehoo.com/google%e4%b9%9f%e4%b8%8d%e6%98%af%e4%b8%87%e8%83%bd%e7%9a%84.htm，我期望他转向到http://www.jiehoo.com/google%e4%b9%9f%e4%b8%8d%e6%98%af%e4%b8%87%e8%83%bd%e7%9a%84.htm，但是它总是转向到http://www.jiehoo.com/index.php，很奇怪，后来突然想到这个规则定义可能是有顺序的（没有系统的学习mod_rewrite），试了下，果然如此：
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^jiehoo.com [NC]
RewriteRule ^(.*)$ http://www.jiehoo.com/$1 [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

我刚开始是把上面的那个规则写到后面的，因为那个规则是wordpress需要的。

]]> http://www.jiehoo.me/mod_rewrite%e8%a7%84%e5%88%99%e6%98%af%e6%9c%89%e9%a1%ba%e5%ba%8f%e7%9a%84.htm/feed 1 服务器的硬件问题 http://www.jiehoo.me/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%9a%84%e7%a1%ac%e4%bb%b6%e9%97%ae%e9%a2%98.htm http://www.jiehoo.me/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%9a%84%e7%a1%ac%e4%bb%b6%e9%97%ae%e9%a2%98.htm#comments Sun, 05 Mar 2006 17:54:06 +0000 Cherami http://www.jiehoo.com/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%9a%84%e7%a1%ac%e4%bb%b6%e9%97%ae%e9%a2%98.htm 去年一年JR的服务器一直处于时常崩溃的境地，后面我写了一个shell脚本监测服务进程的状态并可以自动重启从一定程度解决了这个问题，但是没有从根本上解决，我一直怀疑是服务器的硬件问题，因为我们的那个服务器投入使用的调试期竟然有三个月之久，最开始服务商并不承认是他们的服务器的硬件问题，怀疑我们的软件有问题，但是我们在另外一个机器上正在跑的JR是完全正常的，后来我好不容易在第N次重装系统的时候发现他们的硬盘有问题，换了硬盘后问题缓解，但是还不是非常稳定，最终他们的人换了内存才更好了一点。今年春节前服务器彻底崩溃，更换了服务器，他们并没有给服务器配置那个监控服务，但是服务器稳定的工作到我回来，至今也没有发生过宕机的问题，由此证明了去年一年我在服务器维护上的时间投入全是拜奸商所赐。

]]> http://www.jiehoo.me/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%9a%84%e7%a1%ac%e4%bb%b6%e9%97%ae%e9%a2%98.htm/feed 0 igenus最新版的问题 http://www.jiehoo.me/igenus%e6%9c%80%e6%96%b0%e7%89%88%e7%9a%84%e9%97%ae%e9%a2%98.htm http://www.jiehoo.me/igenus%e6%9c%80%e6%96%b0%e7%89%88%e7%9a%84%e9%97%ae%e9%a2%98.htm#comments Tue, 13 Dec 2005 20:00:07 +0000 Cherami http://www.jiehoo.com/igenus%e6%9c%80%e6%96%b0%e7%89%88%e7%9a%84%e9%97%ae%e9%a2%98.htm 今天帮朋友装igenus，使用的最新版igenus_2.0.2_20040901_release.tgz
但是很多页面都有类似Warning: mysql_fetch_object(): supplied argument is not a valid MySQL result
resource in这样的信息，到官方网站看了下也没有找到什么好的资料，后来朋友查了下，要在那些mysql函数前加@就可以了，搜索全部的php文件，在以下四个函数前加@把问题搞定“
mysql_num_rows
mysql_query
mysql_fetch_object
mysql_field_seek

发现这个版本的代码有点混乱，这些函数，有的自己加了@，有的没有加。

]]> http://www.jiehoo.me/igenus%e6%9c%80%e6%96%b0%e7%89%88%e7%9a%84%e9%97%ae%e9%a2%98.htm/feed 0 Red Hat9下解决无法画图的问题 http://www.jiehoo.me/red-hat9%e4%b8%8b%e8%a7%a3%e5%86%b3%e6%97%a0%e6%b3%95%e7%94%bb%e5%9b%be%e7%9a%84%e9%97%ae%e9%a2%98.htm http://www.jiehoo.me/red-hat9%e4%b8%8b%e8%a7%a3%e5%86%b3%e6%97%a0%e6%b3%95%e7%94%bb%e5%9b%be%e7%9a%84%e9%97%ae%e9%a2%98.htm#comments Mon, 21 Nov 2005 21:31:15 +0000 Cherami http://www.jiehoo.com/red-hat9%e4%b8%8b%e8%a7%a3%e5%86%b3%e6%97%a0%e6%b3%95%e7%94%bb%e5%9b%be%e7%9a%84%e9%97%ae%e9%a2%98.htm 已经有几个人问我这个问题了。
整理下写下来了。
对于以控制台方式启动的Red
Hat9服务器而言，需要启动一个虚拟的图形环境，安装的软件包就是XFree86-Xvfb-4.3.0-2.i386.rpm，在配置前先用rpm
-q XFree86-Xvfb查一下有没有安装，没有的话就要安装了，有可能这个包依赖的很多包都没有装，一下是个大致的列表，可能都要安装：
desktop-file-utils-0.3-5.i386.rpm    
XFree86-base-fonts-4.3.0-2.i386.rpm
Glide3-20010520-25.i386.rpm          
XFree86-xauth-4.3.0-2.i386.rpm
switchdesk-3.9.8-15.i386.rpm         
XFree86-Xvfb-4.3.0-2.i386.rpm
XFree86-4.3.0-2.i386.rpm             
xinitrc-3.32-1.noarch.rpm
XFree86-75dpi-fonts-4.3.0-2.i386.rpm

可以以rpm -ivh *.rpm把这几个一起装

完成后修改下/etc/rc文件，在最后加下面一行：
Xvfb :1 -screen 0 1280×1024x8 &

然后修改tomcat的启动脚本，要给JAVA加-Djava.awt.headless=true

]]> http://www.jiehoo.me/red-hat9%e4%b8%8b%e8%a7%a3%e5%86%b3%e6%97%a0%e6%b3%95%e7%94%bb%e5%9b%be%e7%9a%84%e9%97%ae%e9%a2%98.htm/feed 0 在apache2下配置mod_limitipconn的问题 http://www.jiehoo.me/%e5%9c%a8apache2%e4%b8%8b%e9%85%8d%e7%bd%aemod_limitipconn%e7%9a%84%e9%97%ae%e9%a2%98.htm http://www.jiehoo.me/%e5%9c%a8apache2%e4%b8%8b%e9%85%8d%e7%bd%aemod_limitipconn%e7%9a%84%e9%97%ae%e9%a2%98.htm#comments Fri, 28 Oct 2005 18:07:05 +0000 Cherami http://www.jiehoo.com/%e5%9c%a8apache2%e4%b8%8b%e9%85%8d%e7%bd%aemod_limitipconn%e7%9a%84%e9%97%ae%e9%a2%98.htm 昨天按照一些文安装配置了mod_limitipconn，但是其实大部分的文章在说明的时候并没有说清楚，其中最大的一个问题就是安装以后安装程序修改httpd.conf文件是有问题的，默认情况下是添加了：
LoadModule limitipconn_module modules/mod_limitipconn.so
AddModule mod_limitipconn.c

其实后面的那个AddModule mod_limitipconn.c是要删除的，否则apache2不能正常启动，AddModule似乎是apache1.3的语法。

]]> http://www.jiehoo.me/%e5%9c%a8apache2%e4%b8%8b%e9%85%8d%e7%bd%aemod_limitipconn%e7%9a%84%e9%97%ae%e9%a2%98.htm/feed 0 apache2下的可以限速和IP数的模块 http://www.jiehoo.me/apache2%e4%b8%8b%e7%9a%84%e5%8f%af%e4%bb%a5%e9%99%90%e9%80%9f%e5%92%8cip%e6%95%b0%e7%9a%84%e6%a8%a1%e5%9d%97.htm http://www.jiehoo.me/apache2%e4%b8%8b%e7%9a%84%e5%8f%af%e4%bb%a5%e9%99%90%e9%80%9f%e5%92%8cip%e6%95%b0%e7%9a%84%e6%a8%a1%e5%9d%97.htm#comments Fri, 28 Oct 2005 06:47:44 +0000 Cherami http://www.jiehoo.com/apache2%e4%b8%8b%e7%9a%84%e5%8f%af%e4%bb%a5%e9%99%90%e9%80%9f%e5%92%8cip%e6%95%b0%e7%9a%84%e6%a8%a1%e5%9d%97.htm 可以限速的找到两个，一个是Bandwidth Module，Version 0.5rc1， Bandwidth and Connection control per Virtual Host or Directory， Last Updated January 28th, 2005，http://www.ivn.cl/apache/
另外一个mod_cband，Version 0.9，A virtual host
bandwidth-limiting module provided to solve the problem of limiting
virtualhosts bandwidth usage，Last Updated September 07th, 2005，http://cband.linux.pl/

可以限制连接数的也有两个：

mod_vhost_limit，v0.1，
Restrict the number of simultaneous connections per vhost，
Last Modified : 2004.02.26，http://www.ivn.cl/apache/

mod_limitipconn，Version 0.22，Limit the number of simultaneous connections from a single client IP
address. Contains rudimentary support for detection of proxy clients，Last Updated July 22nd, 2003，http://dominia.org/djao/limitipconn2.html

]]> http://www.jiehoo.me/apache2%e4%b8%8b%e7%9a%84%e5%8f%af%e4%bb%a5%e9%99%90%e9%80%9f%e5%92%8cip%e6%95%b0%e7%9a%84%e6%a8%a1%e5%9d%97.htm/feed 0 服务器破天荒的连续工作了12个小时以上 http://www.jiehoo.me/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%a0%b4%e5%a4%a9%e8%8d%92%e7%9a%84%e8%bf%9e%e7%bb%ad%e5%b7%a5%e4%bd%9c%e4%ba%8612%e4%b8%aa%e5%b0%8f%e6%97%b6%e4%bb%a5%e4%b8%8a.htm http://www.jiehoo.me/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%a0%b4%e5%a4%a9%e8%8d%92%e7%9a%84%e8%bf%9e%e7%bb%ad%e5%b7%a5%e4%bd%9c%e4%ba%8612%e4%b8%aa%e5%b0%8f%e6%97%b6%e4%bb%a5%e4%b8%8a.htm#comments Tue, 30 Aug 2005 17:41:28 +0000 Cherami http://www.jiehoo.com/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%a0%b4%e5%a4%a9%e8%8d%92%e7%9a%84%e8%bf%9e%e7%bb%ad%e5%b7%a5%e4%bd%9c%e4%ba%8612%e4%b8%aa%e5%b0%8f%e6%97%b6%e4%bb%a5%e4%b8%8a.htm 从昨天下午服务器宕机后打电话让机房重启开始（大约五点半）到今天早上9点半，差不多16个小时服务器连续工作，更可贵的是tomcat也一次都没有死，真是一个奇迹。
不过实际上还是做了一些工作，但是我到现在都不知道是哪个工作让服务器稳定的工作的，回想一下做的内容：

  • 修改服务器的状态监控脚本，不再使用ps -e|grep jsvc而是使用ps -fC jsvc，另外就是将两个tomcat的启动隔离开，哪个死掉了只重启死掉的那个。但是由于服务器一直没有死掉过，因此这个可能不是主要因素。
  • 屏蔽了一个IP，好像是瀛海威的用户的，这个可能是一个重要因素
  • 和服务商说我们的服务器开始的时候几个月没有能使用就是频繁死机，最后查明是内存的问题，如果还这样就要求更换内存（难道真的是服务商做的手脚？）
  • 换用了JDK5，但是已经是今天前的事情了。

又看了一遍，比较合理的嫌疑是遭到攻击，因为根据日志分析的结果那个IP近几天都对我们网站的大量内容有访问，而昨天偶然之间发现日志分析在统
计访问量时实际上是统计访问的不同内容的，同一地址的访问只算一个，因此一万多的访问就是意味着访问了网站的一万多个不同的内容，这个应该不是正常人可以
办到的，只能是程序遍历或者是大量用户使用同一个IP出口。先封掉再说，再查查看那个IP。

]]> http://www.jiehoo.me/%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%a0%b4%e5%a4%a9%e8%8d%92%e7%9a%84%e8%bf%9e%e7%bb%ad%e5%b7%a5%e4%bd%9c%e4%ba%8612%e4%b8%aa%e5%b0%8f%e6%97%b6%e4%bb%a5%e4%b8%8a.htm/feed 0 Linux内核模块编程指南 http://www.jiehoo.me/linux%e5%86%85%e6%a0%b8%e6%a8%a1%e5%9d%97%e7%bc%96%e7%a8%8b%e6%8c%87%e5%8d%97.htm http://www.jiehoo.me/linux%e5%86%85%e6%a0%b8%e6%a8%a1%e5%9d%97%e7%bc%96%e7%a8%8b%e6%8c%87%e5%8d%97.htm#comments Mon, 01 Aug 2005 23:36:03 +0000 Cherami http://www.jiehoo.com/linux%e5%86%85%e6%a0%b8%e6%a8%a1%e5%9d%97%e7%bc%96%e7%a8%8b%e6%8c%87%e5%8d%97.htm 这个是我大学的时候利用寒假的时间翻译的，记得当时还特意让我妈买了一个电取暖器，窝在家里很长时间才弄完的，可惜时间太长，原件我这里都没有了，现在也没有找到可以下载全部内容的地方了。贴个链接在这里做个纪念吧，毕竟是我最开始为开源做出的一点贡献。

Linux内核模块编程指南

]]> http://www.jiehoo.me/linux%e5%86%85%e6%a0%b8%e6%a8%a1%e5%9d%97%e7%bc%96%e7%a8%8b%e6%8c%87%e5%8d%97.htm/feed 0 RPM常用命令 http://www.jiehoo.me/rpm%e5%b8%b8%e7%94%a8%e5%91%bd%e4%bb%a4.htm http://www.jiehoo.me/rpm%e5%b8%b8%e7%94%a8%e5%91%bd%e4%bb%a4.htm#comments Thu, 28 Jul 2005 04:03:01 +0000 Cherami http://www.jiehoo.com/rpm%e5%b8%b8%e7%94%a8%e5%91%bd%e4%bb%a4.htm
  • 安装：rpm -ivh xxx.nn.m.i386.rpm
  • 卸载：rpm -ivh xxx
  • 升级：rpm -Uvh xxx.nn.m.i386.rpm
  • 查询：rpm -q xxx
  • 信息：rpm -qi xxx
  • 文件：rpm -ql xxx
  • 编译：rpm -ivh –rebuild xxx.src.rpm
  • 签名：rpm –checksig xxx
    • ]]>     http://www.jiehoo.me/rpm%e5%b8%b8%e7%94%a8%e5%91%bd%e4%bb%a4.htm/feed 0     ip-sysctl.txt http://www.jiehoo.me/ip-sysctltxt.htm http://www.jiehoo.me/ip-sysctltxt.htm#comments Wed, 27 Jul 2005 05:25:41 +0000 Cherami http://www.jiehoo.com/ip-sysctltxt.htm /proc/sys/net/ipv4/* Variables: ip_forward - BOOLEAN 0 - disabled (default) not 0 - enabled Forward Packets between interfaces. This variable is special, its change resets all configuration parameters to their default state (RFC1122 for hosts, RFC1812 for routers) ip_default_ttl - INTEGER default 64 ip_no_pmtu_disc - BOOLEAN Disable Path MTU Discovery. default FALSE IP Fragmentation: ipfrag_high_thresh - INTEGER Maximum memory used to reassemble IP fragments. When ipfrag_high_thresh bytes of memory is allocated for this purpose, the fragment handler will toss packets until ipfrag_low_thresh is reached. ipfrag_low_thresh - INTEGER See ipfrag_high_thresh ipfrag_time - INTEGER Time in seconds to keep an IP fragment in memory. ipfrag_secret_interval - INTEGER Regeneration interval (in seconds) of the hash secret (or lifetime for the hash secret) for IP fragments. Default: 600 INET peer storage: inet_peer_threshold - INTEGER The approximate size of the storage. Starting from this threshold entries will be thrown aggressively. This threshold also determines entries' time-to-live and time intervals between garbage collection passes. More entries, less time-to-live, less GC interval. inet_peer_minttl - INTEGER Minimum time-to-live of entries. Should be enough to cover fragment time-to-live on the reassembling side. This minimum time-to-live is guaranteed if the pool size is less than inet_peer_threshold. Measured in jiffies(1). inet_peer_maxttl - INTEGER Maximum time-to-live of entries. Unused entries will expire after this period of time if there is no memory pressure on the pool (i.e. when the number of entries in the pool is very small). Measured in jiffies(1). inet_peer_gc_mintime - INTEGER Minimum interval between garbage collection passes. This interval is in effect under high memory pressure on the pool. Measured in jiffies(1). inet_peer_gc_maxtime - INTEGER Minimum interval between garbage collection passes. This interval is in effect under low (or absent) memory pressure on the pool. Measured in jiffies(1). TCP variables: tcp_syn_retries - INTEGER Number of times initial SYNs for an active TCP connection attempt will be retransmitted. Should not be higher than 255. Default value is 5, which corresponds to ~180seconds. tcp_synack_retries - INTEGER Number of times SYNACKs for a passive TCP connection attempt will be retransmitted. Should not be higher than 255. Default value is 5, which corresponds to ~180seconds. tcp_keepalive_time - INTEGER How often TCP sends out keepalive messages when keepalive is enabled. Default: 2hours. tcp_keepalive_probes - INTEGER How many keepalive probes TCP sends out, until it decides that the connection is broken. Default value: 9. tcp_keepalive_intvl - INTEGER How frequently the probes are send out. Multiplied by tcp_keepalive_probes it is time to kill not responding connection, after probes started. Default value: 75sec i.e. connection will be aborted after ~11 minutes of retries. tcp_retries1 - INTEGER How many times to retry before deciding that something is wrong and it is necessary to report this suspicion to network layer. Minimal RFC value is 3, it is default, which corresponds to ~3sec-8min depending on RTO. tcp_retries2 - INTEGER How may times to retry before killing alive TCP connection. RFC1122 says that the limit should be longer than 100 sec. It is too small number. Default value 15 corresponds to ~13-30min depending on RTO. tcp_orphan_retries - INTEGER How may times to retry before killing TCP connection, closed by our side. Default value 7 corresponds to ~50sec-16min depending on RTO. If you machine is loaded WEB server, you should think about lowering this value, such sockets may consume significant resources. Cf. tcp_max_orphans. tcp_fin_timeout - INTEGER Time to hold socket in state FIN-WAIT-2, if it was closed by our side. Peer can be broken and never close its side, or even died unexpectedly. Default value is 60sec. Usual value used in 2.2 was 180 seconds, you may restore it, but remember that if your machine is even underloaded WEB server, you risk to overflow memory with kilotons of dead sockets, FIN-WAIT-2 sockets are less dangerous than FIN-WAIT-1, because they eat maximum 1.5K of memory, but they tend to live longer. Cf. tcp_max_orphans. tcp_max_tw_buckets - INTEGER Maximal number of timewait sockets held by system simultaneously. If this number is exceeded time-wait socket is immediately destroyed and warning is printed. This limit exists only to prevent simple DoS attacks, you _must_ not lower the limit artificially, but rather increase it (probably, after increasing installed memory), if network conditions require more than default value. tcp_tw_recycle - BOOLEAN Enable fast recycling TIME-WAIT sockets. Default value is 0. It should not be changed without advice/request of technical experts. tcp_tw_reuse - BOOLEAN Allow to reuse TIME-WAIT sockets for new connections when it is safe from protocol viewpoint. Default value is 0. It should not be changed without advice/request of technical experts. tcp_max_orphans - INTEGER Maximal number of TCP sockets not attached to any user file handle, held by system. If this number is exceeded orphaned connections are reset immediately and warning is printed. This limit exists only to prevent simple DoS attacks, you _must_ not rely on this or lower the limit artificially, but rather increase it (probably, after increasing installed memory), if network conditions require more than default value, and tune network services to linger and kill such states more aggressively. Let me to remind again: each orphan eats up to ~64K of unswappable memory. tcp_abort_on_overflow - BOOLEAN If listening service is too slow to accept new connections, reset them. Default state is FALSE. It means that if overflow occurred due to a burst, connection will recover. Enable this option _only_ if you are really sure that listening daemon cannot be tuned to accept connections faster. Enabling this option can harm clients of your server. tcp_syncookies - BOOLEAN Only valid when the kernel was compiled with CONFIG_SYNCOOKIES Send out syncookies when the syn backlog queue of a socket overflows. This is to prevent against the common 'syn flood attack' Default: FALSE Note, that syncookies is fallback facility. It MUST NOT be used to help highly loaded servers to stand against legal connection rate. If you see synflood warnings in your logs, but investigation shows that they occur because of overload with legal connections, you should tune another parameters until this warning disappear. See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow. syncookies seriously violate TCP protocol, do not allow to use TCP extensions, can result in serious degradation of some services (f.e. SMTP relaying), visible not by you, but your clients and relays, contacting you. While you see synflood warnings in logs not being really flooded, your server is seriously misconfigured. tcp_stdurg - BOOLEAN Use the Host requirements interpretation of the TCP urg pointer field. Most hosts use the older BSD interpretation, so if you turn this on Linux might not communicate correctly with them. Default: FALSE tcp_max_syn_backlog - INTEGER Maximal number of remembered connection requests, which are still did not receive an acknowledgment from connecting client. Default value is 1024 for systems with more than 128Mb of memory, and 128 for low memory machines. If server suffers of overload, try to increase this number. tcp_window_scaling - BOOLEAN Enable window scaling as defined in RFC1323. tcp_timestamps - BOOLEAN Enable timestamps as defined in RFC1323. tcp_sack - BOOLEAN Enable select acknowledgments (SACKS). tcp_fack - BOOLEAN Enable FACK congestion avoidance and fast retransmission. The value is not used, if tcp_sack is not enabled. tcp_dsack - BOOLEAN Allows TCP to send "duplicate" SACKs. tcp_ecn - BOOLEAN Enable Explicit Congestion Notification in TCP. tcp_reordering - INTEGER Maximal reordering of packets in a TCP stream. Default: 3 tcp_retrans_collapse - BOOLEAN Bug-to-bug compatibility with some broken printers. On retransmit try to send bigger packets to work around bugs in certain TCP stacks. tcp_wmem - vector of 3 INTEGERs: min, default, max min: Amount of memory reserved for send buffers for TCP socket. Each TCP socket has rights to use it due to fact of its birth. Default: 4K default: Amount of memory allowed for send buffers for TCP socket by default. This value overrides net.core.wmem_default used by other protocols, it is usually lower than net.core.wmem_default. Default: 16K max: Maximal amount of memory allowed for automatically selected send buffers for TCP socket. This value does not override net.core.wmem_max, "static" selection via SO_SNDBUF does not use this. Default: 128K tcp_rmem - vector of 3 INTEGERs: min, default, max min: Minimal size of receive buffer used by TCP sockets. It is guaranteed to each TCP socket, even under moderate memory pressure. Default: 8K default: default size of receive buffer used by TCP sockets. This value overrides net.core.rmem_default used by other protocols. Default: 87380 bytes. This value results in window of 65535 with default setting of tcp_adv_win_scale and tcp_app_win:0 and a bit less for default tcp_app_win. See below about these variables. max: maximal size of receive buffer allowed for automatically selected receiver buffers for TCP socket. This value does not override net.core.rmem_max, "static" selection via SO_RCVBUF does not use this. Default: 87380*2 bytes. tcp_mem - vector of 3 INTEGERs: min, pressure, max low: below this number of pages TCP is not bothered about its memory appetite. pressure: when amount of memory allocated by TCP exceeds this number of pages, TCP moderates its memory consumption and enters memory pressure mode, which is exited when memory consumption falls under "low". high: number of pages allowed for queueing by all TCP sockets. Defaults are calculated at boot time from amount of available memory. tcp_app_win - INTEGER Reserve max(window/2^tcp_app_win, mss) of window for application buffer. Value 0 is special, it means that nothing is reserved. Default: 31 tcp_adv_win_scale - INTEGER Count buffering overhead as bytes/2^tcp_adv_win_scale (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale), if it is <= 0. Default: 2 tcp_rfc1337 - BOOLEAN If set, the TCP stack behaves conforming to RFC1337. If unset, we are not conforming to RFC, but prevent TCP TIME_WAIT assassination. Default: 0 tcp_low_latency - BOOLEAN If set, the TCP stack makes decisions that prefer lower latency as opposed to higher throughput. By default, this option is not set meaning that higher throughput is preferred. An example of an application where this default should be changed would be a Beowulf compute cluster. Default: 0 ip_local_port_range - 2 INTEGERS Defines the local port range that is used by TCP and UDP to choose the local port. The first number is the first, the second the last local port number. Default value depends on amount of memory available on the system: > 128Mb 32768-61000 < 128Mb 1024-4999 or even less. This number defines number of active connections, which this system can issue simultaneously to systems not supporting TCP extensions (timestamps). With tcp_tw_recycle enabled (i.e. by default) range 1024-4999 is enough to issue up to 2000 connections per second to systems supporting timestamps. ip_nonlocal_bind - BOOLEAN If set, allows processes to bind() to non-local IP addresses, which can be quite useful - but may break some applications. Default: 0 ip_dynaddr - BOOLEAN If set non-zero, enables support for dynamic addresses. If set to a non-zero value larger than 1, a kernel log message will be printed when dynamic address rewriting occurs. Default: 0 icmp_echo_ignore_all - BOOLEANicmp_echo_ignore_broadcasts - BOOLEAN If either is set to true, then the kernel will ignore either all ICMP ECHO requests sent to it or just those to broadcast/multicast addresses, respectively. icmp_ratelimit - INTEGER Limit the maximal rates for sending ICMP packets whose type matches icmp_ratemask (see below) to specific targets. 0 to disable any limiting, otherwise the maximal rate in jiffies(1) Default: 100 icmp_ratemask - INTEGER Mask made of ICMP types for which rates are being limited. Significant bits: IHGFEDCBA9876543210 Default mask: 0000001100000011000 (6168) Bit definitions (see include/linux/icmp.h): 0 Echo Reply 3 Destination Unreachable * 4 Source Quench * 5 Redirect 8 Echo Request B Time Exceeded * C Parameter Problem * D Timestamp Request E Timestamp Reply F Info Request G Info Reply H Address Mask Request I Address Mask Reply * These are rate limited by default (see default mask above) icmp_ignore_bogus_error_responses - BOOLEAN Some routers violate RFC1122 by sending bogus responses to broadcast frames. Such violations are normally logged via a kernel warning. If this is set to TRUE, the kernel will not give such warnings, which will avoid log file clutter. Default: FALSE igmp_max_memberships - INTEGER Change the maximum number of multicast groups we can subscribe to. Default: 20 conf/interface/* changes special settings per interface (where "interface" is the name of your network interface)conf/all/* is special, changes the settings for all interfaces log_martians - BOOLEAN Log packets with impossible addresses to kernel log. log_martians for the interface will be enabled if at least one of conf/{all,interface}/log_martians is set to TRUE, it will be disabled otherwise accept_redirects - BOOLEAN Accept ICMP redirect messages. accept_redirects for the interface will be enabled if: - both conf/{all,interface}/accept_redirects are TRUE in the case forwarding for the interface is enabled or - at least one of conf/{all,interface}/accept_redirects is TRUE in the case forwarding for the interface is disabled accept_redirects for the interface will be disabled otherwise default TRUE (host) FALSE (router) forwarding - BOOLEAN Enable IP forwarding on this interface. mc_forwarding - BOOLEAN Do multicast routing. The kernel needs to be compiled with CONFIG_MROUTE and a multicast routing daemon is required. conf/all/mc_forwarding must also be set to TRUE to enable multicast routing for the interface medium_id - INTEGER Integer value used to differentiate the devices by the medium they are attached to. Two devices can have different id values when the broadcast packets are received only on one of them. The default value 0 means that the device is the only interface to its medium, value of -1 means that medium is not known. Currently, it is used to change the proxy_arp behavior: the proxy_arp feature is enabled for packets forwarded between two devices attached to different media. proxy_arp - BOOLEAN Do proxy arp. proxy_arp for the interface will be enabled if at least one of conf/{all,interface}/proxy_arp is set to TRUE, it will be disabled otherwise shared_media - BOOLEAN Send(router) or accept(host) RFC1620 shared media redirects. Overrides ip_secure_redirects. shared_media for the interface will be enabled if at least one of conf/{all,interface}/shared_media is set to TRUE, it will be disabled otherwise default TRUE secure_redirects - BOOLEAN Accept ICMP redirect messages only for gateways, listed in default gateway list. secure_redirects for the interface will be enabled if at least one of conf/{all,interface}/secure_redirects is set to TRUE, it will be disabled otherwise default TRUE send_redirects - BOOLEAN Send redirects, if router. send_redirects for the interface will be enabled if at least one of conf/{all,interface}/send_redirects is set to TRUE, it will be disabled otherwise Default: TRUE bootp_relay - BOOLEAN Accept packets with source address 0.b.c.d destined not to this host as local ones. It is supposed, that BOOTP relay daemon will catch and forward such packets. conf/all/bootp_relay must also be set to TRUE to enable BOOTP relay for the interface default FALSE Not Implemented Yet. accept_source_route - BOOLEAN Accept packets with SRR option. conf/all/accept_source_route must also be set to TRUE to accept packets with SRR option on the interface default TRUE (router) FALSE (host) rp_filter - BOOLEAN 1 - do source validation by reversed path, as specified in RFC1812 Recommended option for single homed hosts and stub network routers. Could cause troubles for complicated (not loop free) networks running a slow unreliable protocol (sort of RIP), or using static routes. 0 - No source validation. conf/all/rp_filter must also be set to TRUE to do source validation on the interface Default value is 0. Note that some distributions enable it in startup scripts. arp_filter - BOOLEAN 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request. 0 - (default) The kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load- balancing, does this behaviour cause problems. arp_filter for the interface will be enabled if at least one of conf/{all,interface}/arp_filter is set to TRUE, it will be disabled otherwise tag - INTEGER Allows you to write a number, which can be used as required. Default value is 0. (1) Jiffie: internal timeunit for the kernel. On the i386 1/100s, on theAlpha 1/1024s. See the HZ define in /usr/include/asm/param.h for the exactvalue on your system. Alexey Kuznetsov.kuznet-AT-ms2.inr.ac-DOT-ru Updated by:Andi Kleenak-AT-muc-DOT-deNicolas Delondelon.nicolas-AT-wanadoo-DOT-fr /proc/sys/net/ipv6/* Variables: IPv6 has no global variables such as tcp_*. tcp_* settings under ipv4/ alsoapply to IPv6 [XXX?]. bindv6only - BOOLEAN Default value for IPV6_V6ONLY socket option, which restricts use of the IPv6 socket to IPv6 communication only. TRUE: disable IPv4-mapped address feature FALSE: enable IPv4-mapped address feature Default: FALSE (as specified in RFC2553bis) IPv6 Fragmentation: ip6frag_high_thresh - INTEGER Maximum memory used to reassemble IPv6 fragments. When ip6frag_high_thresh bytes of memory is allocated for this purpose, the fragment handler will toss packets until ip6frag_low_thresh is reached. ip6frag_low_thresh - INTEGER See ip6frag_high_thresh ip6frag_time - INTEGER Time in seconds to keep an IPv6 fragment in memory. ip6frag_secret_interval - INTEGER Regeneration interval (in seconds) of the hash secret (or lifetime for the hash secret) for IPv6 fragments. Default: 600 conf/default/*: Change the interface-specific default settings. conf/all/*: Change all the interface-specific settings. [XXX: Other special features than forwarding?] conf/all/forwarding - BOOLEAN Enable global IPv6 forwarding between all interfaces. IPv4 and IPv6 work differently here; e.g. netfilter must be used to control which interfaces may forward packets and which not. This also sets all interfaces' Host/Router setting 'forwarding' to the specified value. See below for details. This referred to as global forwarding. conf/interface/*: Change special settings per interface. The functional behaviour for certain settings is different depending on whether local forwarding is enabled or not. accept_ra - BOOLEAN Accept Router Advertisements; autoconfigure using them. Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled. accept_redirects - BOOLEAN Accept Redirects. Functional default: enabled if local forwarding is disabled. disabled if local forwarding is enabled. autoconf - BOOLEAN Configure link-local addresses using L2 hardware addresses. Default: TRUE dad_transmits - INTEGER The amount of Duplicate Address Detection probes to send. Default: 1 forwarding - BOOLEAN Configure interface-specific Host/Router behaviour. Note: It is recommended to have the same setting on all interfaces; mixed router/host scenarios are rather uncommon. FALSE: By default, Host behaviour is assumed. This means: 1. IsRouter flag is not set in Neighbour Advertisements. 2. Router Solicitations are being sent when necessary. 3. If accept_ra is TRUE (default), accept Router Advertisements (and do autoconfiguration). 4. If accept_redirects is TRUE (default), accept Redirects. TRUE: If local forwarding is enabled, Router behaviour is assumed. This means exactly the reverse from the above: 1. IsRouter flag is set in Neighbour Advertisements. 2. Router Solicitations are not sent. 3. Router Advertisements are ignored. 4. Redirects are ignored. Default: FALSE if global forwarding is disabled (default), otherwise TRUE. hop_limit - INTEGER Default Hop Limit to set. Default: 64 mtu - INTEGER Default Maximum Transfer Unit Default: 1280 (IPv6 required minimum) router_solicitation_delay - INTEGER Number of seconds to wait after interface is brought up before sending Router Solicitations. Default: 1 router_solicitation_interval - INTEGER Number of seconds to wait between Router Solicitations. Default: 4 router_solicitations - INTEGER Number of Router Solicitations to send until assuming no routers are present. Default: 3 use_tempaddr - INTEGER Preference for Privacy Extensions (RFC3041). <= 0 : disable Privacy Extensions == 1 : enable Privacy Extensions, but prefer public addresses over temporary addresses. > 1 : enable Privacy Extensions and prefer temporary addresses over public addresses. Default: 0 (for most devices) -1 (for point-to-point devices and loopback devices) temp_valid_lft - INTEGER valid lifetime (in seconds) for temporary addresses. Default: 604800 (7 days) temp_prefered_lft - INTEGER Preferred lifetime (in seconds) for temorary addresses. Default: 86400 (1 day) max_desync_factor - INTEGER Maximum value for DESYNC_FACTOR, which is a random value that ensures that clients don't synchronize with each other and generage new addresses at exactly the same time. value is in seconds. Default: 600 regen_max_retry - INTEGER Number of attempts before give up attempting to generate valid temporary addresses. Default: 5 icmp/*:ratelimit - INTEGER Limit the maximal rates for sending ICMPv6 packets. 0 to disable any limiting, otherwise the maximal rate in jiffies(1) Default: 100 IPv6 Update by:Pekka Savola <pekkas-AT-netcore-DOT-fi>YOSHIFUJI Hideaki / USAGI Project <yoshfuji@linux-ipv6.org> $Id: ip-sysctl.txt,v 1.20 2001/12/13 09:00:18 davem Exp $ ]]> http://www.jiehoo.me/ip-sysctltxt.htm/feed 0 Linux下SYN的设置 http://www.jiehoo.me/linux%e4%b8%8bsyn%e7%9a%84%e8%ae%be%e7%bd%ae.htm http://www.jiehoo.me/linux%e4%b8%8bsyn%e7%9a%84%e8%ae%be%e7%bd%ae.htm#comments Wed, 27 Jul 2005 05:01:38 +0000 Cherami http://www.jiehoo.com/linux%e4%b8%8bsyn%e7%9a%84%e8%ae%be%e7%bd%ae.htm 参考文章为：SYN攻击的基本原理、工具及检测方法以及防范技术

    LINUX相关的内容摘录如下：

    1. 激活SYN cookies：echo 1 > /proc/sys/net/ipv4/tcp_syncookies
    2. 增加最大半连接数：sysctl -w net.ipv4.tcp_max_syn_backlog=”2048″
    3. 缩短超时时间：sysctl -w net.ipv4.tcp_synack_retries=”1″

    其实第一个也应该可以使用sysctl设置的，因为sysctl也是设置/proc/sys/net/ipv4目录下的对应文件的值。

    另外这个设置都是一次性的，系统启动后就丢失了，要一直有效需要写入启动脚本，例如/etc/rc.d/rc.local

    有点奇怪LINUX系统下为什么要用这种方式设置这些值，每个变量用一个文件设置。

    ]]>     http://www.jiehoo.me/linux%e4%b8%8bsyn%e7%9a%84%e8%ae%be%e7%bd%ae.htm/feed 0     隐藏Apache的服务器配置信息 http://www.jiehoo.me/%e9%9a%90%e8%97%8fapache%e7%9a%84%e6%9c%8d%e5%8a%a1%e5%99%a8%e9%85%8d%e7%bd%ae%e4%bf%a1%e6%81%af.htm http://www.jiehoo.me/%e9%9a%90%e8%97%8fapache%e7%9a%84%e6%9c%8d%e5%8a%a1%e5%99%a8%e9%85%8d%e7%bd%ae%e4%bf%a1%e6%81%af.htm#comments Fri, 08 Jul 2005 18:02:57 +0000 Cherami http://www.jiehoo.com/%e9%9a%90%e8%97%8fapache%e7%9a%84%e6%9c%8d%e5%8a%a1%e5%99%a8%e9%85%8d%e7%bd%ae%e4%bf%a1%e6%81%af.htm ServerTokens ProductOnly 和 ServerSignature Off 微调 Apache 的返回信息 http://windtear.net/archives/2005/05/30/000676.html apache 的 httpd.conf 有两个配置可以控制是否显示服务器信息给用户ServerTokensServerSignature 默认条件下会把apache版本 系统 模块都显示出来 (HTTP 返回头)还有如果列举目录的话 会显示域名信息(文件列表正文)(http://httpd.apache.org/docs/mod/core.html表明ServerSignature已经默认Off了)如果不想要就可以调这两个参数 ServerTokensServerSignature ServerSignature On|Off|EMailServerTokens Minimal|ProductOnly|OS|Full ServerTokens Prod[uctOnly]    Server sends (e.g.): Server: ApacheServerTokens Min[imal]    Server sends (e.g.): Server: Apache/1.3.0ServerTokens OS    Server sends (e.g.): Server: Apache/1.3.0 (Unix)ServerTokens Full (or not specified)    Server sends (e.g.): Server: Apache/1.3.0 (Unix) PHP/3.0 MyMod/1.2   ]]> >ServerTokens ProductOnly 和 ServerSignature Off 微调 Apache 的返回信息

    http://windtear.net/archives/2005/05/30/000676.html

    apache 的 httpd.conf 有两个配置可以控制是否显示服务器信息给用户
    ServerTokens
    ServerSignature

    默认条件下会把apache版本 系统 模块都显示出来 (HTTP 返回头)
    还有如果列举目录的话 会显示域名信息(文件列表正文)
    (http://httpd.apache.org/docs/mod/core.html表明ServerSignature已经默认Off了)
    如果不想要就可以调这两个参数

    ServerTokens
    ServerSignature

    ServerSignature On|Off|EMail
    ServerTokens Minimal|ProductOnly|OS|Full

    ServerTokens Prod[uctOnly]
        Server sends (e.g.): Server: Apache
    ServerTokens Min[imal]
        Server sends (e.g.): Server: Apache/1.3.0
    ServerTokens OS
        Server sends (e.g.): Server: Apache/1.3.0 (Unix)
    ServerTokens Full (or not specified)
        Server sends (e.g.): Server: Apache/1.3.0 (Unix) PHP/3.0 MyMod/1.2

     

    ]]>     http://www.jiehoo.me/%e9%9a%90%e8%97%8fapache%e7%9a%84%e6%9c%8d%e5%8a%a1%e5%99%a8%e9%85%8d%e7%bd%ae%e4%bf%a1%e6%81%af.htm/feed 0