How to block network connection to all `root` process?

kittygirl

11/16/22, 3:35 AM

My system is debian 10 with nftables.
output of nethogs as below:

? root     192.168.2.10:59100-172.217.27.138:443 
? root     192.168.2.10:59086-172.217.27.138:443 
? root     192.168.2.10:59082-172.217.27.138:443 
? root     192.168.2.10:59062-172.217.27.138:443 
? root     192.168.2.10:59058-172.217.27.138:443 
? root     192.168.2.10:59054-172.217.27.138:443 
? root     192.168.2.10:59030-172.217.27.138:443 
? root     192.168.2.10:59026-172.217.27.138:443
? root     192.168.2.10:42314-27.19.249.194:443  
? root     192.168.2.10:49788-216.58.200.234:443

I ss -pl | grep 59100 but got nothing,then I plan to block all root process to network connection.
How to do it?

1 + 2

networking

nftables

Esa Jokinen

11/16/22, 5:56 AM

This seems like *an XY problem*. If I get it right, you don't understand what these connections are and try to solve it simply by blocking them. But there's a problem with this approach: root might need Internet access for e.g. system updates, and if there are malicious connections from root, it's already game over.

kittygirl

11/16/22, 6:36 AM

@EsaJokinen,I want to block root all the time,except update.

Score:2

Server

Esa Jokinen

11/16/22, 8:30 AM

With iptables, this would be rather easy with the owner match extension:

sudo iptables -A OUTPUT -p all -m owner --uid-owner 0 -j DROP

Likewise, nftables has matching by socket UID / GID:

sudo nft add rule filter output meta skuid 0 counter

0 + 2

kittygirl

11/16/22, 9:15 AM

I add `log prefix "drop root: " meta skuid 0 counter drop` in nftables rule,seemed works fine. ps.What's the meaning of `meta`?

kittygirl

11/16/22, 9:21 AM

Cound I use `!` or `not` to set only one user pass,such as `log prefix "drop root: " meta ! skuid 1000 counter drop`?

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How to block network connection to all `root` process?

TH: จะบล็อกการเชื่อมต่อเครือข่ายกับกระบวนการ 'รูท' ทั้งหมดได้อย่างไร

RO: Cum să blochezi conexiunea la rețea la toate procesele „rădăcină”?

RU: Как заблокировать сетевое подключение ко всем процессам `root`?

VI: Làm cách nào để chặn kết nối mạng với tất cả quá trình `root`?

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