iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
git reset --hard deliberately resets a local branch’s position, index, and working tree to a chosen commit; forcing a push can then replace remote branch history. An EC2 NAT instance has a different safeguard: source/destination checking must be disabled so it can forward other instances’ traffic. Both operations remove a protection, but for unrelated reasons—and neither is safe to do without checking what it protects.
What the two “guardrails” protect
Nnamdi Felix Ibe’s Day 30 walkthrough pairs a Git history rewrite with an AWS networking exercise. The shared lesson is operational, not technical: understand a safeguard before overriding it. Git’s fast-forward rule protects remote commit history; EC2 source/destination checking filters traffic at an instance or network interface. One does not cause or configure the other.
| Operation | Protection being overridden | What the change enables |
|---|---|---|
| Force-push after a hard reset | Git’s default rejection of a non-fast-forward update | Replacing the remote branch tip with rewritten history |
| Disable source/destination checking on a NAT instance | EC2’s default check that traffic has the instance as its source or destination | Forwarding packets for other instances |
How to reset and push a Git branch without surprising collaborators
What git reset --hard changes
Git’s reset documentation describes --hard as moving the current branch to the selected commit and resetting both the index and working tree to match it. Any uncommitted changes in the affected working tree can be lost. A reset does not necessarily erase every possible recovery route, but that is not a reason to treat it as reversible: first verify the branch and target commit, and preserve work you may need.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Why the push may be rejected
A regular push normally updates a remote branch only when the new tip is a fast-forward of its current tip. After a reset, the local branch may no longer contain the remote branch’s latest commit, so Git rejects the push rather than silently discarding remote history. The git-push documentation explains that a force option can override this protection; repository configuration or server-side hooks can still refuse the update.
#1 Best Overall
Check before rewriting remote history
- Confirm the branch and reset target. Make sure the branch you intend to move is checked out and that the selected commit is correct.
- Inspect the changes on both sides. Identify the local commits that will be removed from the branch tip and check whether the remote contains commits absent from your local history.
- Preserve needed work. Commit or otherwise save uncommitted changes before using
git reset --hard. - Coordinate on shared branches. Tell collaborators before replacing branch history so they can avoid building work on the tip you plan to remove.
- Force-push only when the rewrite is intentional. A forced update can discard remote history; it is not a routine fix for every rejected push.
Why an EC2 NAT instance needs source/destination checking disabled
Amazon Web Services states: “Each EC2 instance performs source/destination checks by default.” A NAT instance receives and sends packets whose source or destination is another instance. That forwarding role conflicts with the default check, so AWS requires disabling it on the NAT instance. AWS also notes that routing, NAT, or firewall functions may require disabling the check on the network interface.
Disabling the check is necessary for this use, but it does not by itself provide internet connectivity. The instance also needs the right placement, forwarding configuration, and routes.
Configure the path from a private subnet to S3
Ibe’s scenario describes a private EC2 instance with a cron job attempting to upload to S3 every minute. If the instance cannot reach S3, check the network path rather than assuming a failed upload job proves the cron schedule is wrong. A NAT instance provides a route out of the VPC; it does not, on its own, guarantee access to a particular AWS service or bucket.
Recommended Free Tools
Verify the VPC and subnet path first
The walkthrough reports that its lab did not have an internet gateway, despite the task’s apparent assumption that one existed. Discovering the actual network state before configuring a route is essential: AWS’s NAT-instance guidance requires the NAT instance to be in a public subnet with internet-gateway reachability. Confirm the VPC’s internet gateway attachment, the NAT instance’s subnet, and the relevant route tables before proceeding.
Enable forwarding and configure NAT on the instance
The author’s Linux implementation enables IP forwarding and applies an iptables MASQUERADE rule through the outbound interface. Those are examples, not universal commands: interface names, Linux distributions, persistence across reboot, and network-service configuration vary. Check that forwarding is enabled, the rule uses the actual outbound interface, and the instance’s security-group and network settings permit the intended traffic.
Disable the check and direct private traffic through the NAT instance
Disable source/destination checking on the NAT instance, then configure the private subnet’s route table so the relevant outbound traffic targets the NAT instance’s network interface (ENI). Validate that the route is active and points to the intended interface. A missing internet gateway, an incorrect route target, or a NAT rule bound to the wrong interface can each leave private instances without the expected path.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What this walkthrough establishes—and what it does not
The article is a tutorial report, not a comparative test of NAT options. It describes NAT instances as a cost-oriented and exam-relevant subject and contrasts them with managed NAT Gateways, but it does not establish current prices or availability, nor does the cited AWS material verify the walkthrough’s claimed 100 Gbps figure. Do not use that number or assume one option is cheaper without checking current AWS documentation and pricing for the relevant region and configuration.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
