Urgent Help Needed to Reprogram Cisco Router 1800/1900 Series. Command Line

Hey guys i need some help asap.

I have two cisco 1800-1900 series router and i need to reprogram then due to a DDoS attack. Long story short we suffered a DDoS attack today and Comcast changed our static IP address. show i need to reconfigure our router and the VPN tunnel.

Everything was configured and working properly. It has been a long time since i have worked on CLI with cisco. What is the easiest way to do this?

This is what is needed.

Router 1#

- Change WAN IP Address
- Change Gateway Address
- Change DHCP DNS servers (All other DHCP and Internal LAN stays the same)
Router #2

- Change VPN Tunnel to connect to new IP address of Router #1's new WAN IP
I could really use a step by step. I remember many of the commands but i am sure i will forget something.

For this use the follow as the old and new IP addresses:

Router 1 old WAN 23.24.xx.xx
Router 1 new WAN 50.243.xx.xx

THANK YOU EVERYONE!
Jokeefe1012Asked:
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Don JohnstonInstructorCommented:
It would be easier if we could see the existing (sanitized) configuration.

Some of the commands are specific to the interface that they're assigned to. i.e. fa0/0 or fa1/1, etc.

Another approach is to copy the current configuration to a text editor. Then search for the old IP address. Take any lines with the old IP address and copy them to a new text file and change the IP address to the new one. Then do the same with the gateway IP address.  And DNS addresses and so on. Then paste the text from the new text file into the config.

Sorry the answer isn't "do A then B then C and D".
Netman66Commented:
Agree on the text output and global search and replace of old IP with new IP then reload.

Easiest way if you aren't sure.

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AkinsdNetwork AdministratorCommented:
Router 1#

- Change WAN IP Address
show ip int b

look for the interface with the ip you provided - in this example, let's say the interface is F0/1 and new ip is 50.243.10.10 /24

conf t
int fa0/1
ip address 50.243.10.10 255.255.255.0



- Change Gateway Address
show ip route

look for 0.0.0.0 0.0.0.0 23.24.x.x

no ip route 0.0.0.0 0.0.0.0 23.24.x.x
ip route 0.0.0.0 0.0.0.0 50.243.10.11


Note
The IP will be on the same subnet as your WAN IP

- Change DHCP DNS servers (All other DHCP and Internal LAN stays the same)
Router #2
https://www.youtube.com/watch?v=Z95v2KQGM-Y

- Change VPN Tunnel to connect to new IP address of Router #1's new WAN IP
I could really use a step by step. I remember many of the commands but i am sure i will forget something.

https://www.youtube.com/watch?v=sIbi_bYb2k4

Hope this helps
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