Linux

63475 readers

911 users here now

From Wikipedia, the free encyclopedia

Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

Rules

Posts must be relevant to operating systems running the Linux kernel. GNU/Linux or otherwise.
No misinformation
No NSFW content
No hate speech, bigotry, etc

Related Communities

Community icon by Alpár-Etele Méder, licensed under CC BY 3.0

founded 6 years ago

MODERATORS

nooter692@lemmy.ml

AgreeableLandscape@lemmy.ml

MarcellusDrum@lemmy.ml

cypherpunks@lemmy.ml

cyclohexane@lemmy.ml

d3Xt3r@lemmy.nz

The behavior of /24 vs /32 addresses when using iptables (programming.dev)

submitted 21 hours ago by emotional_soup_88@programming.dev to c/linux@lemmy.ml

16 comments fedilink hide all child comments

I added a rule to accept connections from 192.168.1.135/24, since my router is configured to hand out /24 addresses. Then, iptables -L -v showed that connections from 192.168.1.0/24 are accepted. When I change the rule to accept connections from .135/32 - or from .135 without specifying the subnet -, it not only works as intended, but it also resolves the hostname correctly.

Why?

unsolicited "why do you still use iptables" advice not welcome :D

you are viewing a single comment's thread
view the rest of the comments

[–] emotional_soup_88@programming.dev 1 points 18 hours ago (1 children)

Thank you very much! :)

Interesting why iptables behaves like that though. Because, if I understand it correctly, specifying any address between 192.168.1.[0...255]/24 will result in all addresses in that range to be accepted? So, the only way to actually single out one host is to use the mask /32...?

[–] CosmicGiraffe@lemmy.world 3 points 16 hours ago (1 children)

Yes, exactly. The convention is to use the lowest address in the range (e.g. 192.168.1.0/24), since you're allowing a range of addresses rather than a single one.

The reason to do this is that many firewall rules will be based on sets of addresses - you might want to allow traffic from any device in your local network without having to add individual rules for each

[–] emotional_soup_88@programming.dev 1 points 16 hours ago

Tomorrow, at work, I'm gonna brag about what I have learned here today, until my colleagues' ears fall off.

Thanks again! :)