Tagged Questions

Content related to computer security., i.e. content about policies, mechanisms, etc. needed make sure data is not leaked or corrupted and services available in all circumstances.

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0answers
84 views

What keys are generated during Debian 7.4 (Wheezy) installation?

We are concerned lest /dev/random (or /dev/urandom) be hit too early in the installation process for adequate entropy to be developed. In a basic Debian 7.4 installation (SSH Server and basic ...
2
votes
2answers
94 views

In OS X Darwin, why can I interfere with text input across user sessions using cat?

OS X Darwin: Disrupting Terminal Sessions Across User Identities How, in Brief: with cat < /dev/ttys_, in Terminal. My Question This OS X 10.9.2 Darwin behaviour seems odd to me, and I would ...
1
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1answer
108 views

Is there a selinux, httpd, or PHP configuration that prevents reading mounted drives?

I'm moving a virtualized centos web server over that has an all-to-small hard drive to a new machine and I hooked up a bigger drive for hosting videos and downloads and stuff. W When I try to run a ...
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6answers
884 views

Program a file to self-destruct at a given time

Does anyone know whether there is a command in linux that can set attributes to file so that the file can disappear after certain time. For example, if I set one attribute to file as "1/1/2015", so ...
8
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3answers
235 views

Trap: can't su as root, can't change group to wheel, ssh as root prohibited

Is this a trap? I made these steps in FreeBSD 10: 1) ssh as root prohibited 2) logged as user 3) su as root 4) as root chsh changed name of user "user" to "luser" 5) exit from ...
1
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0answers
97 views

Ulimits and pam modules

Can you explain me the relation of ulimit setting on a proccess and line session required pam_limits.so in pam module. In wich modules i really require this line? I have this line in pam.d/su ...
1
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1answer
109 views

File monitoring to pre-empt hacker

We have a hacker occasionally attempting to hack a site, and so far unsuccessful, but I would like a way to determine if the site has been compromised (i.e., files edited). The type of attacks are LFI ...
14
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6answers
5k views

Can root/superuser read my read-protected files?

On shared unix hosting, if I have a file sensitive-data.txt and I issue: chmod 600 sensitive-data.txt Can root user still read my file? Specifically I'm wondering if it's safe to store my password ...
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1answer
80 views

How to compile c, c++ and python code as “Released/Final” version? [closed]

I want to know if there are ways to compile C, C++ and Python code in order to not be able to reverse engineering it over Linux or not? I have heard there are some ways over Windows to do it, but I ...
5
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2answers
301 views

Writing a “telnet server” type program that uses SSH instead of telnet

So people have written server programs using telnet in which the user simply does telnet server.com and this connects them to the server program, which then provides them with a textual program they ...
4
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1answer
146 views

How does iptables recognize packet state?

Consider these two sets of rules: Set A -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT -A INPUT -j REJECT -A OUTPUT -j ACCEPT Set B -A INPUT -m conntrack --ctstate ...
3
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2answers
153 views

using SUID bit to drop privileges

So this is a description of the system I'm working on : a "manager" process spawns all the other applications. The manager application runs as root user. so now, any process that it spawns also ...
0
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1answer
271 views

Is it possible to make a standard user that can gain NO access to root?

I'm a very new beginner learning how to use Linux. I have very little experience so far in different distros. I've set Kali Linux as the OS on a remote PC. Users will be connecting to it via SSH and I ...
2
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2answers
1k views

Do I need to encapsulate awk variables in quotes in order to sanitize them?

As per an answer on stackoverflow, it's my understanding that encapsulating bash variables in double-quotes is a fairly safe way of sanitizing user input. What about awk variables? For example, if ...
2
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1answer
56 views

How it is decided which certificate of a Certificate Authority will be used in a system certificate chain [closed]

I am looking for PKI (Public Key Infrastructure) knowledge and particularly at OS's built-in certificate chain list. Of course on Windows the company decides which certificate will be built-in, but ...
0
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1answer
43 views

Maximum password length

Is there a maximum password length on unix systems? If so, what is that limit and is it distribution dependent?
5
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1answer
1k views

Using LDAP for authentication, how can I safely disable/deactivate an account without deleting it?

We use LDAP for authentication for thousands of users. The primary tactic we have been employing to make a user unable to login, without removing their account, is to change the LDAP attribute ...
0
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2answers
54 views

Will autologin create remote security problems?

In Debian, I setup nodm, such that my computer logs in automatically when it is turned on. I am not concerned about thieves accessing the computer directly, but compared to a setup using GDM, can such ...
4
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1answer
79 views

What is not accessible from userspace?

I read somewhere (3.1.3) that there's a high ring (supervisor mode) and a low ring (user mode) and that some "things" can be run only from the highest ring. What do they mean by "things"? I'd guess ...
-1
votes
2answers
68 views

Is my system compromised or vulnerable to attacks

I ran netstat -lntup with the network connected. Recently one of my friends exploited my linux system using backtrack so I had to format it. Now I want to know whether I'm still being exploited or ...
3
votes
1answer
99 views

Has my machine been compromised?

I have a bunch of lines in my machine if I use "ps aux". Here are the lines: samp 8413 0.0 0.0 968 564 ? S 12:28 0:00 ./ssh 150 samp 8419 0.0 0.0 956 380 ? ...
3
votes
1answer
291 views

How do I change the Java Security level?

We've got an ancient (internal use only) self-signed app that refuses to run now with the changes to the JRE. Working on getting a code signing certificate and rebuilding it, but that's horribly slow ...
1
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2answers
164 views

What ports are essential and should generally be allowed on a Linux system?

I'm running a desktop computer, but one with high threat risk. I've blocked all ports using a firewall except: HTTP, HTTPS, DNS, one port for torrent client. Do any common processes in distros ...
1
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1answer
62 views

How can I protect my computer when the only way to access the internet is though a compromised internet connection?

I access the network through a connection which is most likely compromised by a MITM attack. I can't do much about it. What steps should I take to lessen the influence of this attack. I'm especially ...
0
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1answer
45 views

Is this method safe or recommended for moving a /home directory?

I have my linux install on a small disk. I want to put the home directory on a different hard-drive. I was thinking of using this and then this. Would this work? Is there a better way? Should I just ...
3
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1answer
2k views

How to Block SSH Brute Force via Iptables and How does it work?

I'm planning to add the following rules to iptables to stop ssh brute force attack which are common these days. -A INPUT -i eth0.103 -p tcp -m tcp --dport 4522 -m state --state NEW -m recent --set ...
2
votes
1answer
253 views

Reconfigure login through root ftp (lost ssh access)

My question is twofold. I need to somehow re-enable telnet and/or ssh in a device where I currently only have root ftp access. Also, if I am going about this wrong, please let me know. Details to ...
3
votes
1answer
195 views

How to disable root user on OpenBSD?

So there is a desktop and root permission isn't needed on it (or if it's needed, then reboot to single mode/whateverlivecd fix a config file-> get root, do the stuff with it and at the end, disable ...
2
votes
2answers
3k views

Why does sshd requires an absolute path?

Why does sshd require an absolute path when restarting, e.g /usr/sbin/sshd rather than sshd Are there any security implications? P.S the error message: # sshd sshd re-exec requires execution with ...
2
votes
1answer
170 views

Was my Unix server compromised?

Someone asked if this constituted a break-in and wondered if their server had been compromised. Jan 12 04:16:51 foo sshd[26725]: Failed password for root from 61.174.51.207 port 1076 ssh2 Jan 12 ...
0
votes
1answer
78 views

Break In Attempt

mysql service has vanished from my vps and service is down since yesterday where can see from /var/log/secure file it says break in attempt from an ip that is not known to me but cannot tell if the ...
4
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2answers
109 views

What are the methods to protect home folder files from other applications runing as the same user?

I would like to enforce the security access of some files in my Home folder. My concern is about processes running with the same privileges as me having access to those files. I've been wondering ...
3
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1answer
61 views

Run Windows program on Linux in a secure way

I am trying to find a way to achieve a secure execution of Windows programs inside a Linux installation. I suppose that a Windows malware should not do any damage (infect the machine), if executed ...
2
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4answers
336 views

Keeping my production webserver updated

I have a production webserver (CentOS 6.5) and I just wanted to know how do I keep this updated interms of security updates and stable. For example, is it safe interms of not breaking anything on the ...
5
votes
1answer
239 views

Secure access to remote SSH tunnel

So I wish to be able to access my Raspberry Pi (which I keep at home behind a firewall) remotely. One option is to use a static IP address, but as a poor student I don't want to fork out for one, and ...
1
vote
1answer
77 views

How to make my laptop safe & secure from any accidents like deleting by mistake?

This should be a general question. This Q sprung my mind yesterday late evening because I accidentally deleted files from another partition rather than from the partition I was intending to do. I'm ...
35
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9answers
4k views

How to trigger a system self destruct with a certain password is entered

How do I configure my system to destroy all personal data when a certain password is entered? The motivation behind this being NSA stuff. I imagine there being three primary usage cases. At login, ...
1
vote
1answer
77 views

SELinux and Trusted OS - can SELinux be confined to hardware level root?

I am exploring on SE Linux and while doing so i found it as an example of Trusted OS. Is it really an example of Trusted OS stack like TrouSerS ? SELinux as per my understanding modifies the Linux ...
1
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1answer
87 views

How to securely download rpmfusion keys

The Actual Problem I am trying to solve I am trying to automatically configure my fedora installations via salt to automatically have the rpmfusion repositories installed. In order to do this ...
3
votes
2answers
164 views

How to implement logwatch functionality on top of systemd journal?

Logwatch scans logfiles with regular intervals, collects errors and stuff, then mails it to the admin. This was back in syslog and logfiles days. What's the corresponding solution for systemd's ...
0
votes
2answers
109 views

Which runlevel is best for a Linux (Debian) server (DBMS/SCM)?

I currently try to harden the system and the security of a Debian server running a database and a source code management. I just want networking and me (one user) to be able to login. Which runlevel ...
2
votes
2answers
58 views

Securely viewing an encrypted file

I have a file that is gpg encrypted. I would like to view the content of the file, but leave no trace of the output. Lets say for example that the encrypted file has some passwords, and I don't want ...
2
votes
2answers
490 views

Is a -rw-rw-rw- file really inaccessible inside a drwxrwx— directory?

Say I have a directory with these permissions: drwxrwx--- Inside this directory, a file with these permissions: -rw-rw-rw- Is the file readable/writable by everyone or not ? If not, how secure ...
4
votes
1answer
261 views

Myth or reality: SELinux can confine the root user?

I read or heard somewhere (maybe in LinuxCBT's SELinux course; but I'm not sure) that there are online Linux servers, for which the password of the root user is also given. The Linux server is ...
4
votes
1answer
155 views

Is there any point in using `sudo` when you are the sole user of your machine?

I'd like to know if there is any reason why I should use sudo instead of su, taking into account that I am the owner and sole user of my machine (and hence have root access whenever I want). Also, in ...
1
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0answers
229 views

Unable to set capability CAP_SETFCAP by user

The question is about capabilities. I need to allow user to set capabilities using setcap. When I call it by root all goes fine, eg $ sudo setcap cap_dac_override,cap_dac_read_search+ep ./bin_file $ ...
1
vote
1answer
231 views

securely automating a script which requires a key to do its task

I have a script that downloads bank transactions to store in a database. To get these transactions requires a password for each account. The database is encrypted and requires a key to access it. All ...
2
votes
1answer
265 views

I need find 1 simple rootkit to test chkrootkit in centos?

I want to find 1 simple rootkit to test chkrootkit (a tool used to detect rootkit). Please recommend to me 1 rootkit and show me how to set it up or install it.
1
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1answer
109 views

Which software supports DoD 5220-22-M 7 pass standard for SLES 10.4?

"DoD 5220-22-M 7 pass standard" is a secure deletion method. But what software supports it for a SLES 10.4 64bit?
0
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3answers
407 views

noexec on /tmp and /var/tmp directory

Our client servers are running old version of jboss (Jboss 4.0) which has lots of known vulnerabilities. Result is that the server is hacked and we are seeing some unknown executables running from ...