adding dns override

README.md

@@ -12,6 +12,32 @@ This script is used to clean some of the files, docker dangling images, and dock
 
 This PowerShell script is used to backup files from a Windows machine to a remote Samba server. It uses `7zip` to create the zip file, and then sends over the network using SMB protocol.
 
+### `dns-override.sh`
+
+Aggressive, best-effort DNS override script for Linux hosts with support for multiple resolver stacks (`systemd-resolved`, `NetworkManager`, `resolvconf/openresolv`, `dhclient`, `systemd-networkd`, and `ifupdown`) plus direct `/etc/resolv.conf` writes.
+
+It prompts for:
+- 2 required DNS servers
+- 1 optional third DNS server
+
+Validation/features:
+- Accepts IPv4 and IPv6 literals
+- Rejects invalid or duplicate entries
+- Performs reachability checks (warn-only, does not block execution)
+- Can optionally lock `/etc/resolv.conf` with `chattr +i`
+
+Run with `curl | bash`:
+
+```bash
+curl -sSL https://git.ivanch.me/ivanch/server-scripts/raw/branch/main/dns-override.sh | bash
+```
+
+Important notes:
+- Requires interactive TTY input (prompts are read from `/dev/tty`)
+- Requires root privileges (`sudo` is used/re-execed when possible)
+- Script is intentionally aggressive and may restart/reload network services
+- On heavily managed systems (custom agents, immutable images, enterprise policy), behavior is still best-effort
+
 ## Haven Notify
 
 It's a small internal service designed to send notifications to a specified Discord channel via webhooks. It's written in Go and can be easily deployed.