Linux-Anteil anti Beschwerden Server

mysqadmin -uroot -p processlist
可以看出连接的详细资料.

如果只是想看连接数.
直接打mysqladmin status
Threads就是连接数

To ensure that my CentOS machines run as efficiently and securely as possible, I disable a number of services after each installation. The end result is a system that accepts ssh connections on TCP port 22, and on one or more service ports that are in use by the applications hosted on the platform. To get to this state, I go through and disable numerous services that come enabled by default. Here is the default list of services that are enabled after a CentOS 4.4 installation:

$ chkconfig –list | grep on

atd             0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
messagebus      0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
smartd          0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
portmap         0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
sendmail        0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
netfs           0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
cups            0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
irqbalance      0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
rpcgssd         0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
xfs             0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
isdn            0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
autofs          0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
gpm             0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
apmd            0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
crond           0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
acpid           0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
microcode_ctl   0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
pcmcia          0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
cpuspeed        0:off   1:auf    2:auf    3:auf    4:auf    5:auf    6:off
xinetd          0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
rpcidmapd       0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
readahead_early 0:off   1:off   2:off   3:off   4:off   5:auf    6:off
readahead       0:off   1:off   2:off   3:off   4:off   5:auf    6:off
sshd            0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
anacron         0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
network         0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
kudzu           0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
syslog          0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
nfslock         0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
rawdevices      0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off
mdmonitor       0:off   1:off   2:auf    3:auf    4:auf    5:auf    6:off
haldaemon       0:off   1:off   2:off   3:auf    4:auf    5:auf    6:off

Several of these services are required, but several others serve no purpose in my environment, and use CPU and memory resources that would be better allocated to my applications. Since I don’t use RPC services, autofs or NFS, those are the first to get disabled:

$ /sbin/chkconfig –level 0123456 portmap off
$ /sbin/chkconfig –level 0123456 nfslock off
$ /sbin/chkconfig –level 0123456 netfs off
$ /sbin/chkconfig –level 0123456 rpcgssd off
$ /sbin/chkconfig –level 0123456 rpcidmapd off
$ /sbin/chkconfig –level 0123456 autofs off

I also don’t allow individual hosts to receive mail from the outside world, so sendmail gets nixed next:

$ /sbin/chkconfig –level 0123456 sendmail off

On server platforms, who needs printing?:

$ /sbin/chkconfig –level 0123456 cups off

Now we get to the font server, isdn capabilities, console mouse and pcmcia support. I don’t use these services on my servers, so they get disabled as well:

$ /sbin/chkconfig –level 0123456 xfs off
$ /sbin/chkconfig –level 0123456 isdn off
$ /sbin/chkconfig –level 0123456 gpm off
$ /sbin/chkconfig –level 0123456 pcmcia off

Once these services are disabled (and optionally stopped with the service command or a reboot), my netstat output looks nice and clean:

$ netstat –tcp –udp –listening

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State
tcp        0      0 *:ssh                       *:*                         LISTEN

This has served me well over the years, since it reduces boot time (less rc scripts to run), and frees up additional resources for my applications (while this isn’t substantial, every page of memory helps!).

CentOS 5 中OpenSSL和OpenSSH升级

2010-10-24 23:44

把OpenSSL和OpenSSH升级了。CentOS 5.2所带的OpenSSL是0.9.8b，OpenSSH是4.0p1。升级方法如下:

openssh 最新版本（http://www.openssh.com/portable.html）

wget http://www.openssl.org/source/openssl-0.9.8j.tar.gz

tar zxvf openssl-0.9.8j.tar.gz

cd openssl-0.9.8j

./config –prefix=/usr

machen

make test

make install

wget http://openbsd.noc.jgm.gov.ar/pub/OpenBSD/OpenSSH/portable/openssh-5.2p1.tar.gz

tar zxvf openssh-5.2p1.tar.gz

cd openssh-5.2p1

./konfigurieren –prefix=/usr –with-pam –with-zlib –sysconfdir=/etc/ssh –with-ssl-dir=/usr –with-md5-passwords

machen

make install