IPv6 Addresses Types
IPv6 addresses are broadly classified into three categories:
1) Unicast addresses A Unicast address acts as an identifier for a single interface. An IPv6 packet sent to a Unicast address is delivered to the interface identified by that address.
2) Multicast addresses A Multicast address acts as an identifier for a group/set of interfaces that may belong to the different nodes. An IPv6 packet delivered to a Multicast address is delivered to the multiple interfaces.
3) Anycast addresses Anycast addresses act as identifiers for a set of interfaces that may belong to the different nodes. An IPv6 packet destined for an Anycast address is delivered to one of the interfaces identified by the address.
Tags: addresses, IPv6, Types
IPV6 Network Configuration in Linux
Add nameserver to resolv.config
vi /etc/resolv.conf
Add line for ipv6 nameserver
nameserver 1407:f800::113:23:133:101
vi /etc/sysconfig/network
Add a line at the bottom
vi /etc/sysconfig/network-scripts/ifcfg-eth0
Add lines at the bottom
IPV6INIT=yes
IPV6ADDR=
IPV6_DEFAULTGW=
Example:
IPV6INIT=yes
IPV6ADDR=2407:f800:101::2
IPV6_DEFAULTGW=2407:f800:101::1
Restart network services:
Tags: configuration, IPv6, linux, Network
Check the most IP connect to server
netstat -an | grep :80 | awk ‘{print $5}’ | sed -e s/’:.*’/”/g | sort | uniq -c
or
netstat -anp |grep ‘tcp\|udp’ | awk ‘{print $5}’ | cut -d: -f1 | sort | uniq -c | sort -n
or
netstat -ntu | awk ‘{print $5}’ | cut -d: -f1 | sort | uniq -c | sort -n
Tags: check, connect, IP, server
Block an IP from access to your server with IPtable
Use the command netstat -n command to see the IP addresses connected to your server. Once you have found the IP address you want to block you can use the following below command to block them from accessing your server using iptables.
-I INPUT 1 means to insert the rule at the top of the INPUT table (which means it will get looked at first)
-s IP-ADDRESSS is the source address of the packets we want to deal with
-j DROP means dump the packets into the void, and forget they ever happened.
iptables -I INPUT 1 -s IP-ADDRESSS -j DROP
Tags: Access, Block, IP, IPtable, server
Add user to sudoers list
sudoers - list of which users may execute what.
Login as root and then run the command visudo, add a line. Replace username to the actual user name.
/etc/sudoers - This file MUST be edited with the ‘visudo’ command as root.
To add all user in wheel group to sudoers list, login as root and then run the command visudo to uncomment the line below, or add this line is it not exist.
Tags: list, sudoers, User
