Can't stop questioning!


Tuyen D. Le September 03, 2023 [Server] #ip #routing


  1. TTL: in ARP is the rental period (after this time, the entry will be deleted)
  2. If the switch does not know which port to send the message to, it will forward to all ports


wget -c
mv download
cd net-snmp-5.7.3/
sudo apt-get install libperl-dev
sudo  make install
cd perl/
perl Makefile.PL
mib2c --help
mib2c -c mib2c.scalar.conf bfcMgmt
mkdir ~/test
cd ~/test/
export LD_LIBRARY_PATH=/usr/local/lib:/usr/lib
mib2c -c mib2c.scalar.conf myScalar
sudo apt-get install libperl-dev -y

wget -c
tar -xzvf net-snmp-5.8.tar.gz 
cd net-snmp-5.8/
sudo  make install

# May be not need
sudo ln -s /usr/local/lib/ /usr/lib/

snmpget -v

cd perl/
perl Makefile.PL
make    | sudo make
mib2c --help
snmptranslate  -M "/test/snmp/all" -m ALL -Ir 
snmptranslate   -m ALL -Ir 

export MIBDIRS=/test/snmp/all
export MIBS=ALL

mib2c -c mib2c.scalar.conf telnetUserName

snmptranslate .
snmptranslate -Ir  


There are two types of UPnP:

  1. Upnp on a Router
    • When enabled: allow devices to open ports themselves without configuring the router
    • dynamically add port formally
    • functions like port forwarding but no need to go to web router to configure
  2. Upnp is often referred to as UPnP IGD for listening to music, watching movies

NTP (Network Time Protocol)

There are two commonly used time standards:

  1. GMT: Greenwitch Mean Time: take the movement of the sun as a standard, according to which 1 day has 86,400s
  2. UTC: based on SI system using quantum clock, according to which 1 day has 86,400,002s --> Nowadays, UTC is used, and GMT is used to refer to timezone

Some countries have daylight saving time DST (Daily Saving Time)

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