! =====================================================================
! CAU HINH MAU: Router Cisco ISR G2 (1921 / 1941 / 2901 / 2911 / 2951) ra internet
! Quay PPPoE qua modem nha mang de che do bridge (VNPT, FPT, Viettel...) + NAT + DHCP + SSH
! Nguon: https://thietbimangcu.com/cau-hinh-mau/
! - gi0/0 = cong WAN noi modem (bridge), gi0/1 = cong LAN.
! - Doi TEN_DANG_NHAP_PPPOE / MAT_KHAU_PPPOE (nha mang cap) va MAT_KHAU_... khac.
! =====================================================================
enable
configure terminal
!
hostname RT-INTERNET
no ip domain-lookup
service password-encryption
enable secret MAT_KHAU_ENABLE
username admin privilege 15 secret MAT_KHAU_ADMIN
ip domain-name congty.local
crypto key generate rsa modulus 2048
ip ssh version 2
line vty 0 15
 login local
 transport input ssh
!
! --- Cong WAN: chi bat PPPoE, khong dat IP ---
interface gi0/0
 description WAN-MODEM-BRIDGE
 no ip address
 pppoe enable group global
 pppoe-client dial-pool-number 1
 no shutdown
!
! --- Giao dien quay so PPPoE ---
interface Dialer1
 description PPPOE-NHA-MANG
 ip address negotiated
 ip mtu 1492
 ip tcp adjust-mss 1452
 ip nat outside
 encapsulation ppp
 dialer pool 1
 ppp authentication chap pap callin
 ppp chap hostname TEN_DANG_NHAP_PPPOE
 ppp chap password MAT_KHAU_PPPOE
 ppp pap sent-username TEN_DANG_NHAP_PPPOE password MAT_KHAU_PPPOE
 no shutdown
!
! --- Cong LAN ---
interface gi0/1
 description LAN
 ip address 192.168.10.1 255.255.255.0
 ip nat inside
 ip tcp adjust-mss 1452
 no shutdown
!
! --- Duong mac dinh ra internet ---
ip route 0.0.0.0 0.0.0.0 Dialer1
!
! --- NAT: ca LAN dung chung IP WAN ---
access-list 1 permit 192.168.10.0 0.0.0.255
ip nat inside source list 1 interface Dialer1 overload
!
! --- DHCP cho LAN ---
ip dhcp excluded-address 192.168.10.1 192.168.10.20
ip dhcp pool LAN
 network 192.168.10.0 255.255.255.0
 default-router 192.168.10.1
 dns-server 8.8.8.8 1.1.1.1
!
end
write memory
!
! --- Neu WAN la IP tinh thay vi PPPoE: bo phan Dialer1, dat thang tren gi0/0 ---
! interface gi0/0
!  ip address IP_WAN SUBNET_MASK
!  ip nat outside
! ip route 0.0.0.0 0.0.0.0 GATEWAY_NHA_MANG
! ip nat inside source list 1 interface gi0/0 overload
!
! --- Kiem tra ---
! show pppoe session
! show ip interface brief
! show ip nat translations
! show ip dhcp binding
! ping 8.8.8.8 source gi0/1