this post was submitted on 07 May 2024
737 points (98.2% liked)
Technology
59087 readers
3313 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
The Option 121 attack is a concern on networks where you don’t.
Exactly where you’d want a VPN. Cafes, hotels, etc.
True that. Hadn't thought of that as it's not my typical VPN use case.
I'm not sure what a VPN provider could do about that though, they don't control the operating system's networking stack. If the user or an outside process that the user decides to trust (i.e. a dhcp server) adds its own network routes, the OS will follow it and route traffic outside of the tunnel.
The defenses I see against it are:
Edit: thinking about it some more, on Linux at least the VPN client could add some iptables rules that block traffic going through any other interface than the tunnel device (i.e. if it's not through tun0 or wg0, drop it). Network routes can't bypass iptables rules, so that should work. It will have the side effect that the VPN connection will appear not to work if someone is using the option 121 trick though, but at least you would know something funny was happening.