TCP/UD`P Port Forwarding port forwarding is set on the router it is able to access to internal host from external. Port Number is looks like phone extension number. DHCP(Will Update Nov 15th) Proxy Proxy is a kind of a server or a service that translates traffic between users and the internet networks. Proxy servers act
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SMTP stand for Simple Message Transfer Protocol. Mail message is sent by using this SMTP protocol. The mail message is relayed by some SMTP server. Almost message is relayed normally and is sent to others. but seldom times, the message is not sent by any reason. SMTP status code is useful for investigating the reason
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Sometimes system troble occur by the disk space problem. we can check root cause by some command. Volume usage per partition Most used disk directory Under / Under /var/ Check journal file size Check size and delte files which are before 3 days
confirm authentication SELECT user, host, plugin FROM mysql.user;
cp /usr/share/zoneinfo/Asia/Tokyo /etc/localtime
check memory #free -t -htotal used free shared buff/cache availableMem: 983M 488M 121M 524K 373M 341MSwap: 0B 0B 0BTotal: 983M 488M 121M ・make 1GM swap files #dd if=/dev/zero of=/var/swap bs=1M count=1024#mkswap /var/swap#swapon /var/swap
root user is able to change root user password. sudo passwd root
yum command is easy to install software in your host. yum list installed Output all installed software yum update [softwarename] ex: yum update httpd it is able to update software by this command. yum list you can know the software which is able to install.
Subnet /n Subnet IP Count /32 255.255.255.255 1 /31 255.255.255.254 2 /30 255.255.255.252 4 /29 255.255.255.248 8 /28 255.255.255.240 16 /27 255.255.255.224 32 /26 255.255.255.192 64 /25 255.255.255.128 128 /24 255.255.255.0 256 /23 255.255.254.0 512 /22 255.255.252.0 1024 /21 255.255.248.0 2048 Subnet IPs The subnet mask is used to define the range of the network.
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compress tar.gz tar -zcvf xxx.tar.gz directory decompression tar.gz tar -zxvf xxxx.tar.gz