0.0.0.0/0 is the IPv4 everything – all possible IPv4 addresses.
::/0 is the IPv6 equivalent of that.
It should be noted that depending on implementation ::/0 can mean either all IPv6 addresses or all IPv4 and IPv6 addresses. That’s because IPv4 addresses can be mapped into IPv6 addresses ::ffff:0:0/96
References
https://serverfault.com/questions/874407/difference-between-0-0-0-0-0-and-0-in-access-control-lists
import ipaddress
def get_ip_range(cidr):
net = ipaddress.ip_network(cidr)
return net[0], net[-1]
cidr = "192.109.82.0/23"
ip_range = get_ip_range(cidr)
start_ip = ip_range[0]
end_ip = ip_range[1]
print("Start ip = ", start_ip)
print("End ip = ", end_ip)
Start ip = 192.109.82.0 End ip = 192.109.83.255
References
https://www.tutorialsbuddy.com/get-ipv4-ipv6-address-range-from-cidr-in-python
nmap -p 22 portquiz.net
time nmap -p 22 portquiz.net
telnet portquiz.net 80
time nmap portquiz.net
time nmap -p- portquiz.net | grep -i open
References
https://superuser.com/questions/1336054/how-to-detect-if-a-network-is-blocking-outgoing-ports
http://portquiz.net/
sudo nano /etc/sysctl.d/99-sysctl.conf
net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1
sudo sysctl -p
References
https://www.linuxbabe.com/ubuntu/disable-ipv6-on-ubuntu
https://askubuntu.com/questions/440649/how-to-disable-ipv6-in-ubuntu-14-04
https://support.purevpn.com/how-to-disable-ipv6-linuxubuntu
Install Linux Kernel 4.9 or Above
TCP BBR is supported by Linux since kernel version 4.9. Use the following command to check your Linux kernel version.
uname -r
Simply install the Hardware Enablement Stack (HWE), which provides newer kernel for Ubuntu LTS releases
sudo apt install --install-recommends linux-generic-hwe-16.04
sudo nano /etc/sysctl.conf
net.core.default_qdisc=fq net.ipv4.tcp_congestion_control=bbr
sudo sysctl -p
References
https://www.linuxbabe.com/ubuntu/enable-google-tcp-bbr-ubuntu
sudo lsof -i sudo netstat -lptu sudo netstat -tulpn
References
https://www.cyberciti.biz/tips/linux-display-open-ports-owner.html
R1# configure terminal R1(config)# service dhcp R1(config)# ip dhcp pool NET-POOL R1(dhcp-config)# network 192.168.1.0 255.255.255.0 R1(dhcp-config)# default-router 192.168.1.1 R1(dhcp-config)# dns-server 192.168.1.5 195.170.0.1
R1(dhcp-config)# domain-name Firewall.cx R1(dhcp-config)# lease 9
R1(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.5 R1(config)# ip dhcp excluded-address 192.168.1.10
R1# show ip dhcp binding
References :
http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/812-cisco-router-dhcp-config.html
RouterA(config)#router rip
RouterA(config-router)#version 2
RouterA(config-router)#network 192.168.10.0
RouterA(config-router)#network 195.14.25.0
RouterA(config-router)#network 195.14.125.0
RouterA(config-router)#no auto-summary
RouterB(config)#router rip
RouterB(config-router)#version 2
RouterB(config-router)#network 192.168.20.0
RouterB(config-router)#network 195.14.25.0
RouterB(config-router)#network 195.14.125.0
RouterA(config-router)#no auto-summary
RouterC(config)#router rip
RouterC(config-router)#version 2
RouterC(config-router)#network 192.168.30.0
RouterC(config-router)#network 195.14.25.0
RouterC(config-router)#no auto-summary
References :
RouterA(config)#router rip
RouterA(config-router)#network 192.168.10.0
RouterA(config-router)#network 195.14.25.0
RouterA(config-router)#network 195.14.125.0
RouterB(config)#router rip
RouterB(config-router)#network 192.168.20.0
RouterB(config-router)#network 195.14.25.0
RouterB(config-router)#network 195.14.125.0
RouterC(config)#router rip
RouterC(config-router)#network 192.168.30.0
RouterC(config-router)#network 195.14.25.0
References :
Router A :
ip route 192.168.3.0 255.255.255.0 192.168.2.2
^ ^ ^
network mask gateway
ip route 192.168.3.0 255.255.255.0 192.168.1.1
^ ^ ^
network mask gateway
Router B :
vice versa to Router A
References :
http://serverfault.com/questions/171551/help-me-understand-the-ip-route-command-for-cisco-routers