Verifying Dynamic Public IP Address

[Jimtron26]

Hi all,

I have an 837 i am configuring for home use. My ISP allocates my public IP address dynamically. I think I have config`d the router correctly but cannot access the internet or run ping or traceroute to a public IP address.

My ISP (BT) do not supply a password to connect with only a username and im not sure if this is a problem.

Does anyone know how I can find out (show command) if the request for an IP address has been accepted by the ISP and I have been allocated an address?

If I can confirm I have a public IP address I can then start to look at the NATing etc

Thanks in advance

Jim

 

[ChrisAC]

BT most certainly do supply password for their DSL services. You still have to authenticate to the RADIUS server.

What does your config look like? Can you ping anything from the router?

Chris.

**********************
Chris A.C, CCNA, CCSA
**********************

 

[Cluebird]

On the router do a 'show ip interface brief'. You should see a summary of the router interfaces including ip addresses. That will tell you if you've picked up a dynamic address.

 

[Jimtron26]

Hi chaps, thanks for the responses.

Here is the output from show ip interface brief

Interface IP-Address OK? Method Status Protocol
ATM0 unassigned YES NVRAM down down
Dialer1 unassigned YES NVRAM up up
Ethernet0 192.168.10.1 YES NVRAM up up
FastEthernet1 unassigned YES unset down down
FastEthernet2 unassigned YES unset down down
FastEthernet3 unassigned YES unset down down
FastEthernet4 unassigned YES unset down down
Virtual-Access1 unassigned YES unset up up
Virtual-Access2 unassigned YES unset down down

It was BT themselves who told me that there is no password, i didnt want to grill the guy too much as he got lost on the term "subnet mask". It doesnt look like im getting an IP address, but before I ring BT and rip strips off them, my config is below...

Building configuration...

Current configuration : 2308 bytes
!
version 12.3
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$34O9$2/5dkZRf.kROOAFC8.rMT/
!
username netcon password 0 llimte26
no aaa new-model
ip subnet-zero
!
!
ip dhcp excluded-address 192.168.10.1 192.168.10.20
!
ip dhcp pool LANDHCP
network 192.168.10.0 255.255.255.0
default-router 192.168.10.1

ip ips po max-events 100
no ftp-server write-enable

interface Ethernet0
ip address 192.168.10.1 255.255.255.0
ip nat inside
ip virtual-reassembly
no ip route-cache
no ip mroute-cache
hold-queue 100 out

interface ATM0
no ip address
ip route-cache flow
no atm ilmi-keepalive
dsl operating-mode auto
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1


interface FastEthernet1
no ip address
duplex auto
speed auto

interface FastEthernet2
no ip address
duplex auto
speed auto

interface FastEthernet3
no ip address
duplex auto
speed auto

interface FastEthernet4
no ip address
duplex auto
speed auto

interface Dialer1
description ADSL Internet Port
ip address negotiated
ip access-group 102 in
ip nat outside
ip virtual-reassembly
encapsulation ppp
ip route-cache flow
dialer pool 1
dialer-group 1
ppp authentication chap callin
ppp chap hostname ****************

ip classless
ip route 0.0.0.0 0.0.0.0 Dialer1

ip http server
no ip http secure-server
ip nat inside source list 103 interface Dialer1 overload

access-list 101 remark PERMITTED INBOUND INTERNET TRAFFIC
access-list 101 permit tcp any any eq smtp
access-list 101 permit icmp any any
access-list 101 deny ip any any
access-list 102 permit ip any any
access-list 102 permit icmp any any
access-list 103 permit ip 192.168.10.0 0.0.0.255 any
access-list 103 permit ip any 192.168.10.0 0.0.0.255
access-list 103 permit icmp any any
access-list 103 permit ip any any
dialer-list 1 protocol ip permit

control-plane

line con 0
no modem enable
transport preferred all
transport output all
line aux 0
transport preferred all
transport output all
line vty 0 4
password llimte26
login
transport preferred all
transport input all
transport output all

scheduler max-task-time 5000
end

Thank you for your help

Jim

 

[Jimtron26]

Sorry, when i posted the show ip interface brief, the adsl was not connected o ATM shown as down

Here is the output when connected (still no connectivity)

Interface IP-Address OK? Method Status Protocol
ATM0 unassigned YES NVRAM up up
Dialer1 unassigned YES NVRAM up up
Ethernet0 192.168.10.1 YES NVRAM up up
FastEthernet1 unassigned YES unset down down
FastEthernet2 unassigned YES unset down down
FastEthernet3 unassigned YES unset down down
FastEthernet4 unassigned YES unset down down
Virtual-Access1 unassigned YES unset up up
Virtual-Access2 unassigned YES unset up down
Router#

 

[ChrisAC]

Dialer1 has no IP address because you have not authenticated against the RADIUS server. There needs to be a ppp chap username and password.

Chris.

**********************
Chris A.C, CCNA, CCSA
**********************

 

[Jimtron26]

Thanks Chris,

I thought this was the case...

I have a username but BT tell me there is no password...

i think i need to take it up with them

I have a name for British Telecom which mostly comes from my dealings with them but since this is a clean site i will not post what it is...

Thank you for your help and Cluebird too

"Keep smiling and you will win"

Jim

 

[Cluebird]

It looks like your ppp is not negotiating correctly because of authentication not succeeding. What is this entry for: username netcon password 0 llimte26?

If you're using chap, your username and password combination should mirror. Also, are you intending to authenticate the provider? I'm guessing that they are authenticating you but your config shows you're trying to authenticate them, too. If BT isn't expecting this, ppp fails. Try a "debug ppp authentication" and "debug ppp negotiation" to see what's happening with IPCP.

 

[Jimtron26]

ran the debugs and it is as you say, not authenticating.

rang BT who still say there is no password however on some routers you have to state there is no password

I have entered "ppp chap password null" and I now have internet connection through the 837.

Worth remembering I think...

Just one last question, i have permitted any ip traffic into the router. I have one PC connected to it using windows xp sp2 firewall, do i need to restrict traffic to the router or will the PC firewall take care of security?

Thank you both for all of your help