Network (TCP/IP)

wpadmin Uncategorized October 1, 2021

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 (Mail)

wpadmin Uncategorized September 19, 2021

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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linux – most used disk directory

wpadmin Uncategorized April 29, 2021

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

AWS Linux – assign swap file memory

wpadmin Uncategorized April 17, 2021

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

yum command

wpadmin Uncategorized March 20, 2021

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.

Subnetmask /32 to /21

wpadmin Uncategorized March 5, 2021

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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