This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
How to Configure Site-to-Site IPsec VPN on Cisco Secure Firewall (FTD) is one lab change on a Cisco Secure Firewall (FTD) device you administer. A site-to-site tunnel connects two gateways you administer, or one you administer and a peer named in a ticket. Interesting traffic is the prefix pair you wrote. The browser tool drafts text. It does not log in. You still choose the device.
FTD is changed in the manager you use, FMC or the device manager, and then deployed. A CLI snippet from a forum is not the source of truth. Deploy is the apply. One rule. The device name in the manager matches the ticket. One peer, one proposal you both can read, and a pre-shared key that is not in the ticket. prompt-for-this marks the gap.
Do not open the tunnel to 0.0.0.0/0 to see if it comes up. Do not paste a key into chat. The tunnel is up, and one lab prefix reaches the other lab prefix. The previous policy revision is the rollback. Do not deploy to every device.
192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. They belong in the note. They are not prefixes you type onto a production device because they appeared in a draft. example.com is not your hostname. A second session stays open if the change can lock you out.
The change you can finish
Apply nothing during the writing of the note. When the lab window opens, it is one change on the device named in the ticket. Read the draft, then the device, then decide.
Rollback is the file or the revision you saved first. You do not invent a rollback after the only copy is gone.
- Write the hostname and confirm you administer it.
- Save the current config before any draft is applied.
- Generate the draft and delete every line this ticket did not name.
- Remove any 0.0.0.0/0 and any secret.
- Apply one change only when the lab window is open.
- Read the result back and compare it with the ticket.
- Stop. The next feature is a different page.
Mistakes that outlive the command
Site-to-Site IPsec VPN on Cisco Secure Firewall (FTD) goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Pasting a draft you did not read.
- The wrong hostname.
- A default password left in place.
- 0.0.0.0/0 kept from a sample.
- A secret in the ticket or in git.
- Two features in one window.
- No saved config before the change.
- A documentation prefix applied on a production device.
- Do not open the tunnel to 0.0.0.0/0 to see if it comes up. Do not paste a key into chat.
- Calling the generator output a finished production config.
Decisions to write down
One decision for Site-to-Site IPsec VPN on Cisco Secure Firewall (FTD): The hostname matches the ticket. The feature is only Site-to-Site IPsec VPN. The vendor habit was followed: Cisco Secure Firewall (FTD). A current config was saved first. No 0.0.0.0/0 remains. No secret is in the note. The proof you expect is: The tunnel is up, and one lab prefix reaches the other lab prefix. And the parent pillar still owns the design.
Checks before you call it done
Confirm this before you call the change done: The hostname was read from the device. The saved rollback exists. The draft was edited. One change was applied, or none yet because this was the writing hour. The read-back matches the ticket. A second person can say what changed. Management still works. And the next feature is not started. If one of those fails, stop.
# Cisco Secure Firewall (FTD) lab. Review before you paste.
# Feature: Site-to-Site IPsec VPN.
# FTD is changed in the manager you use, FMC or the device manager, and then deployed. A CLI snippet from a forum is not the source of truth.
# Delete 0.0.0.0/0.
# prompt-for-this is not a password.
# 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. They belong in the note. They are not prefixes you type onto a production device because they appeared in a draft.Before you leave the device
How to Configure Site-to-Site IPsec VPN on Cisco Secure Firewall (FTD) ends when the hostname on the device matches the hostname in the ticket. If it does not, you are on the wrong box. Stop. A command that succeeded on the wrong box is not progress.
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