- Update "Lockout user after three failed login attempts", file mentioned no longer contains those lines ?
- descriptions/rationale for all the links to other articles (MAC)
- base64 /dev/urandom | dd bs=1 count=10 2>/dev/null
- use (enhanced?) ACL on partitions
- sudo timeout
- Securely Wipe HDD
- Using File Capabilities Instead Of Setuid
- VNC, proxies, ssl, etc
- browser security (requestpolicy, noscript, sand-boxing browser)
- stack protector gcc flag: Put some text in the page indicationg Archlinux has it by default (See: FS#18864)
- run services as non-root (mention that Arch does this where possible by default - but it needs improvement via feature requests)
- run services in clean namespaces
- run services in chroots
- mention issues with sudo (any X11 application can grab the password, and it is a large setuid binary with potential vulnerabilities)
CentOS Wiki OS Protection Article
This seems to be a good article to cross-reference or to use as a basis to pull in more content here. CC BY SA rights so I suspect it is compatible with the Arch Wiki. http://wiki.centos.org/HowTos/OS_Protection
I am hoping to pull some content in myself, but I am by no means a security guy. I figured some wiser heads might be able to make better use of it than I or correct any mistakes I might make while attempting to contribute.
- Of course the information itself is not licensed/licenseable, however the way it is presented is, so you either study the original article and present the same information here in an original way, or you actually adapt some content from that article, but in that case the licence clearly states that you have to credit the original authors, and I guess you can do it by mentioning the original article in the Summary of your edits, and adding a link to Security#See also.
- Just as a clarification, I know that Help:Style#Hypertext metaphor states "If the upstream documentation for the subject of your article is well-written and maintained, prefer just writing Arch-specific adaptations and linking to the official documentation for general information", however in this case we can't talk about "upstream documentation", that's why the rule doesn't apply and duplication of information is allowed, being CentOS's and Arch's wikis on the "same level" with respect to the information provided.
- -- Kynikos (talk) 02:33, 3 August 2013 (UTC)
- Let's first compare the sections in the two articles and see how they relate:
- Modifying fstab -> Security#Partitions.
- Package installs -> We have Security#Authenticating_packages and a note at the bottom of Security#Partitions.
- Physical protection -> Security#Physical_security
- Restricting root -> We have Security#Use_sudo_instead_of_su which is a good start, but does not mention Ssh#Deny_root_login. File system permissions on
/root, which I think by default are not
700(they should be) should be added to Security#Filesystem permissions.
- Umask restrictions -> We should talk about
umaskin Security#Filesystem permissions.
- Pam modifications -> Realtime process management, a wiki page in desperate need of editing.
- Reaping idle users -> We should cover this in Security#User_setup.
- Restricting cron and at -> We have no equivalent.
- Wireless has to go -> Maybe worth talking about, but this is low-priority unless we are willing to write a more detailed section called "Wireless security" that is about more than just "turn off wireless."
- Sysctl Security -> Covered in Sysctl#TCP/IP stack hardening, maybe we should just link to this.
- Using TCP Wrappers -> I could not find anything on ArchWiki discussing general security practices for
- Beefing up IPTables -> Should be adapted into Iptables, but perhaps Simple Stateful Firewall (an article that has good information, but I am not sure if its name makes sense).
- Tamper Resistance -> We should have a section on logging in general and incorporate tools like this, probably.
- Comments highly appreciated.
- -- Ndt (talk) 05:09, 3 August 2013 (UTC)
- Let's first compare the sections in the two articles and see how they relate:
We now have three sections devoted only to Grsecurity. What can we do about this?
The addition of Security#Grsecurity RBAC seems to be redundant. However, I agree that "RBAC" is a better name for Grsecurity's MAC implementaiton than Security#Access Control Lists. In technical terms ACLs are a subset of RBAC and Grsecurity implmeents both. The Grsecurity patchset only had ACLs[PDF] back in 2005, and the cited case study mentions (it also refers to SELinux as a RBAC implementation, so perhaps SELinux should also be mentioned there):
- This implementation of ACLs creates a form of process-based mandatory access control. It is possible to restrict what a process can and cannot do. Additionally, access can be restricted to an object for any user, even root. Further, these restrictions cannot be changed by normal users. The system will soon offer role-based access control as well.
Probably the right solution for this is:
- Rename Security#Grsecurity RBAC to Security#Role-Based Access Control.
- Discuss both SELinux/Grsecurity implementations there. There is no need for the RBAC section to be Grsecurity-specific.
- I think it is best to give general recommendations here rather than something like "install Grsecurity to make your kernel secure".
- The right solution is probably to expand Security#Kernel Hardening and discuss Wikipedia:PaX and whatnot more generally, mentioning Grsecurity as an implementation.
- I do think Security#Kernel Hardening should probably be moved lower on the page, closer to Security#Mandatory access control/Security#Network and Firewalls/Security#Authenticating packages since that seems to better suit the logical flow of the article.
- I can't comment on the content since I don't know much about it, but allow me to add some notes:
- The different security models (RBAC, MAC, DAC, ACL, ...) should be compared/described separately from the individual implementations (SELinux, Tomoyo, AppArmor, ...). Meaning there should be separate sections for each group, but mainly "RBAC is significantly faster then SELinux." does not make much sense.
- There should always be provided alternatives, not just 1:1 mapping (like in case of RBAC and Grsecurity).
- Descriptions of both groups can be provided from multiple perspectives. From my experience, in these situations a comparison table is often the best solution.
- I'm not sure about the Security#Kernel Hardening section, should it focus only on security options that require patching the Arch kernel, or also those included in Arch kernel but not activated?
- I hope it makes sense...
- -- Lahwaacz (talk) 22:09, 4 September 2013 (UTC)
- +1, also on mentioning the other options. I further agree with Ndt, moving Security#Kernel Hardening down to below (or above?) Security#Mandatory_access_control and merging the bits for Security#Kernel_parameters into it is better flow, then any other options that are avail without patching into it, followed by PAX and the existing Grsecurity so those get mentioned just before MAC. If someone wants to work on that: I like the comparison/table here maybe it gives some inspiration how to expand. If not, maybe good for See also. (further comparisons are at the bottom of the link). --Indigo (talk) 18:05, 5 September 2013 (UTC)
Nobody as script user
Systemd/cron_functionality#The_pkgstats_service article says that it is better to use
noboby for some tipe of scripts. Is there any person who can explain further and add a note in this article?
- Following the principle of least privilege it is logical to run as many scripts as possible as an unprivileged user. But this is not possible always, e.g. when the script needs (write) access to some file(s) to function properly, you need to provide those privileges. -- Lahwaacz (talk) 13:32, 13 September 2013 (UTC)
Improving the password section
This is a call for ideas and community effort to improve the password recommendations here. I think it's generally agreed that the password section needs (and has, for a long time, needed) some work.
What does the password section need? Is it even necessary - does it make sense for someone to get this information from a wiki? How can we back up our statements, so that we know that the password recommendations made aren't just totally arbitrary (e.g, "at least one number ...")?
Citing sources, I think, is useful here - even though there's an element of password generation that is a matter of opinion, there are many recommendation that can be made that are not opinion. Just my two cents. - Ndt (talk) 21:51, 29 August 2014 (UTC)
- A part I question is:
- Insecure passwords include... Phrases of known words (e.g., all of the lights, correct horse battery staple), even with character substitution.
- How about Diceware (mentioned in Disk_encryption#Choosing_a_strong_passphrase, which is linked to at the end of the section) ? --Alad (talk) 23:48, 31 August 2014 (UTC)
- I've added some clarifications to that sentence: .
- The whole problem comes down to the bits of entropy of a passphrase: if calculated against brute-force attacks, every character from the chosen set counts, because in general they are not releated to each other. In case of Diceware, the characters inside each word are related to each other, and instead what is independent are the words themselves, so the bits must be calculated on a per-word basis (it's vulnerable to dictionary attacks, which can be seen as a form of brute-force attack with every word representing a character in a set of 7776). Now, as you can see from the table in Wikipedia:Password strength, a set of 5 Diceware words is equal to e.g. 10 ASCII characters (64 bits); 7 words == 13 ASCII. Nowadays you'd need more than that to be "safe", but in the end it mostly depends on the importance of what you want to protect. Of course if you choose a phrase of words that are also grammatically related with each other, you're exposing it to some smart dictionary attacks, which would further lower the total bits of entropy.
- Actually, that whole section could be questioned, in fact I could make a strong password even with "Root words or common strings followed or preceded by added numbers, symbols, or characters", if I chose enough "root words" and numbers; I could even make a strong password with dictionary words grammatically related, if the sentence was long enough :) I hope it makes it clearer.
- -- Kynikos (talk) 14:34, 1 September 2014 (UTC)
Removal of incorrect warning
Greetings, I have removed the warning regarding SHA512 on the password hashing section. It's true that one shouldn't use plain sha512 for password hashing, but that isn't what arch (or other Linux distributions) use or are even able to use. What they call "sha512" is crypt_sha512, analogous to cryptmd5 but with the hash function replaced. Crypt_sha512 is a strong sequential function with a configurable iteration parameter. Normal configurations are fairly slow by default and are configurable to be arbritarily slow. I also updated the text to make it clear that it used an iterated sha512 so that others would be less likely to suffer from your confusion. Cheers. --Gmaxwell (talk) 23:39, 24 December 2014 (UTC)
- I was fully aware that it runs a configurable number of sha512 iterations when I made the change. It's not enough iterations to make up for how cheap it is relative to bcrypt/scrypt and it requires very little memory so it does nothing to counter doing billions of hashes per second on a GPU. I don't care enough to argue about it but you shouldn't assume that it had anything to do with confusion. -- thestinger 23:48, 24 December 2014 (UTC)
- I have rephrased the first sentence of the following paragraph to "The default Arch hash sha512 is, however, different than plain SHA512. It is very strong and there is no need to change it." in an attempt to remove the inconsistency. Please proof-read this, since I am a no cryptography expert - the only source I was using was this very discussion. Also I am not native to English, so I can't guarantee I was grammatically correct. Here is the diff to my edit:  Kmph (talk) 20:30, 24 August 2015 (UTC)
- One more thing. Your phrasing does not state whether or not these 5000 iterations, in association with storing passwords in /etc/shadow, actually are secure. With the nearby warning, an impression is made that in might not be enough and that the wiki advises the user to use something else. You have removed this important sentence: "It is very strong and there is no need to change it". If this is appropriate, could you kindly explicitly state whether or not this default Arch's hashing is considered secure enough for normal desktop use? Kmph (talk) 21:00, 24 August 2015 (UTC)
- I'm not the expert, but I'd assume 5000 iterations is "not enough". However I don't know if 999 999 999 or any arbitray high amount is "enough" either. This assessment likely changes as hardware gets more powerful, or more efficient methods are discovered.
- The fact that the hashes are stored in
/etc/shadowshould be sufficient, but I don't know how to accurately word that ("can't be copied or cracked" is vague at best). -- Alad (talk) 21:05, 24 August 2015 (UTC)
- I have practically rewritten the section with these 3 edits, adding lots of links so that people can try to better understand this complicated process.
- Functions like bcrypt and scrypt are indeed aimed at making it more expensive to brute-force passwords with custom-hardware attacks, but if we don't tell people how to decide what function to use, and how to set it up, a warning like that is only FUD...
- — Kynikos (talk) 15:29, 28 November 2015 (UTC)
Let's forget about limits.conf?
Look rapidly at this blog post.
In short: limits.conf is useless for systemd daemons, because systemd has it's own LimitNOFILE=123456, LimitETC=50K.
This is also an issue for desktop users, because users implemented via slices, services and User Manager.
To set per-user resource-limits, now do the following:
mkdir -p /email@example.com/ cat > /firstname.lastname@example.org/limits.conf << EOF [Service] LimitNFILE=131072 EOF systemd daemon-reload systemd restart user@1000
1000 -- is a user's uid. Optional.
- Oops, looks like all this info valid only for dbus-activated user apps like gnome-terminal.