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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4
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2answers
1k views

Purpose of using setuid() in SUID programs

I wonder that an SUID program like passwd is using the setuid() function call. Why does it drop root privileges? Against what types of attack does this help? Buffer-overflow?
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3answers
1k views

SUID permissions - Which is correct?

Trying to secure a Linux server and have little experience with SUID. After executing find / -perm +4000 many programs were discovered. I have seen conflicting advice here and hereon what should ...
8
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9answers
1k views

How to prevent a process from writing files

I want to run a command on Linux in a way that it cannot create or open any files to write. It should still be able to read files as normal (so an empty chroot is not an option), and still be able to ...
5
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2answers
4k views

what is OS hardening in linux or unix?

The term OS hardening itself is misleading/vague to me as i am reading to understand it online here. It seems to me that its something related to making linux/unix box more secure.
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2answers
92 views

how to require sudo to view files?

I have a ssh server. I allow people to connect to it if they want. I do my programming homework on it. I am in trouble with my teacher because people were cheating off it. I need to know how to ...
2
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1answer
2k views

Apache boot without asking for passwd

So I'm maintaining a server which has a verified SSL certificate setup, however there is a password on the private key and so whenever apache is reboot, we get a message asking for the password. This ...
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2answers
4k views

iptables blocking from internet side on eth1?

How to use iptables to deal with two Ethernet ports? eth0 port for LAN use (192.168.1.50 Private IP). eth1 port is connected to the internet via cable modem (80.0.xxx.xxx public IP). ifconfig ...
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2answers
69 views

What permissions should I set if I'm the only user?

I'm the only user on a OS X machine and am wondering what the best practice is for setting permissions on my sensitive files. Specifically, are there reasons to prefer one of the following -rw------- ...
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3answers
349 views

Can a mounted encrypted filesystem be safe from root?

I have access to a shared remote computer from which I would like to run some code I have written which uses an interpreter (not a compiled code). I would like to protect this source code from other ...
13
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2answers
475 views

How can I be sure that a directory or file is actually deleted?

I know that most files, when deleted, aren't actually removed from the disk, and can be recovered later. How can I ensure that a directory I had deleted will actually be removed from the disk? Are ...
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0answers
126 views

Deny/allow a user's access to a port dynamically

I have stumbled upon this little tech dilemma yesterday, and know that there is a solution to it (IRC BNC resellers have it implemented already). However, the exact details and implementation elude ...
6
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2answers
587 views

Can a user brute-force a directory listing without having read permission on the directory?

I noticed that when a user is working in a directory to which he does not have read permission that using cd produces different error messages, depending on whether or not a subdirectory exists: $ ls ...
5
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3answers
273 views

Creating linux distro for use during exam

I'm thinking about creating a liveCD having some linux on it. The distro (let's call it Exam OS) is meant to be used by students during an exam and should be, at least, unpleasent to bypass. Let's ...
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3answers
2k views

Securely delete files on btrfs filesystem

Sometimes, there's the need to delete a file in a filesystem, and make sure that the file is truly gone. A file that contains sensitive passwords, for example, should be throughly wiped from the disk. ...
5
votes
2answers
124 views

Is it more dangerous to connect to the net as root?

If I make some kind of tcp connection to the net as root, is that less safe then making the same tcp connection as a normal user? I have been suspecting for a while that by making a connection as ...
8
votes
1answer
2k views

How to stop users from Switching to Root user

I have disabled the root user login from Sshd.conf file so now no one can login using root user even if they know the password SOMEHOW. Now I have 3 users in server ROOT,EMERG and ORACLE. I want to ...
2
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1answer
470 views

Running a local port scan and found open ports but, don't know what they're used for?

I wrote a very basic python script to port scan my system. I'm running linux-mint lisa: open_ports = [] for port in xrange(65536): conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM) ...
3
votes
1answer
575 views

What should I check after an unauthorized access?

I accidentally left an open port on my router, leaving access to one of my computers via SSH, using a rather insecure password. I noticed because I checked /var/log/auth.log and there is just one ...
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3answers
63 views

execute file in server more safely?

We have a application which takes a C++, C, or Java file as input, executes it, and displays the output to the client. What are the best measures that can be taken so that no security related issues ...
5
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3answers
697 views

Why does time/ident/daytime/comsat run after an OpenBSD 5.2 install?

I installed an OpenBSD 5.2 using "-* & +etc* & +base* & +bsd". After finished with the install, I rebooted, then netstat -at | grep LISTEN, this is what I get for output: Why does so ...
9
votes
1answer
759 views

How can I limit ssh *remote* port forwarding?

I need to limit which ports can be remotely 'ssh -R' forwarded by an user. I know about permitopen option on authorized_keys, but as it says on man page it only limits local 'ssh -L' port forwarding ...
4
votes
3answers
1k views

Is it impossible to run as `root` if the machine isn't rooted?

By default, the user of the device does not have access to certain root objects (e.g. the /data directory). Even though these objects are off-limits, however, it would seem to me that these objects ...
4
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2answers
482 views

How to lock a directory?

I want to block any kind of access to a certain directory unless a password is provided. It could be my root or account password. The directory is residing on an NTFS partition, and this method needs ...
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0answers
49 views

Ossec Installation Error

While installing Ossec Hids 2.6 on Redhat 5.5 installed on Virtual Machine, I got this error message. Whats wrong here.
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1answer
98 views

keeping keys on an auxiliary removable drive

It seems that servers are only as secure as the machine that holds the keys and that in turn means the desktop/screensaver password is the line of defence for not only the desktop itself but any ...
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0answers
718 views

Using Metasploit with 3G USB modem

I have a computer with Linux BackTrack 5 as host and Windows XP as guest on virtual box. I am using Host-Only-Adapter to create virtual LAN and to share USB modem internet as well so that both host ...
-1
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1answer
2k views

What is the security impact of not using tls-remote with OpenVPN

Is it a security issue not using the tls-remote option in OpenVPN? That is not verifying the server's common name. Is a MITM attack possible? Could this be an issue, especially with services like ...
1
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1answer
152 views

Accounts attacked

I have run two commands below. I find some of the accounts attack as below. I do not have the account test,teste,oracle and admin in my home directory. As there system account. How to know which are ...
2
votes
3answers
1k views

How can I securely login remotely to my Linux box over the internet?

I'm pretty much a Linux beginner, but this question has been on my mind. What's the simplest, most secure way to connect to my computer at home from work or from the library, &c? I'm running Mint ...
2
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2answers
1k views

Moving a root directory to a separate partition

I'd like to create a new partition and move the contents of the /var directory to it for the security reason of having /var/www and other subdirectories "mounted" with nosuid, noexec, and nodev ...
1
vote
1answer
1k views

add members of wheel group, sudo access

On Fedora15, following this wiki, I added a user to wheel group, which is already in the sudoer config file. but still I get not-a-sudoer error prompt. Should I specifically name every member of a ...
39
votes
4answers
33k views

What is the point of sshd “UseDNS” option?

I know what it does, but i don't know why. What attack(s) does it prevent ? Is it relevant for all kind of authentication methods ? (hostbased, password, publickey, keyboard-interactive ...)
0
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4answers
777 views

securing SSH and disabling direct root

In these instructions below what appears on my terminal is different so not sure what I should change. After port 22 mine says #AddressFamily any and further down for protocol it has longer line ...
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0answers
82 views

Usage of stunnel for configuring secure services as a default?

Ok, I am aware nothing will beat manual security configuration through your standard daemon config files, but is it bad practice to configure stunnel for all services on say, a production ...
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2answers
119 views

What software(s) should I install on new system(with Linux as a OS) to prevent it from getting hacked? [closed]

I am switching to new system with a OS using Linux.I will be using another system which has windows ultimate which is hacked.I am being cyber bullied. I have given a reference to this as a question on ...
2
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0answers
3k views

How can I connect to a wireless network with hidden SSID using the terminal? [closed]

I'm starting to learn about wireless pentesting with BackTrack, and while learning how to find out the hidden SSID I wondered how could I connect to the wireless network after I discover the SSID. The ...
12
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6answers
59k views

How can I monitor all outgoing requests/connections from my machine?

My machine is a server so I want to ignore connections being made to my server (e.g. when someone visits my website). I want to see only connections/requests being made by my server to other places. ...
3
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1answer
78 views

How is the inherited file descritor vulnerability dealt with in Unices?

Ulrich Drepper describes a vulnerability in programs that have open file descriptors then they fork() and execve() without lots of very careful locking in place. He also talks about new kernel ...
4
votes
2answers
900 views

Is TRESOR included in the latest kernel?

Did TRESOR get included in the mainline Linux kernel? Where would I look to find out? Is there any documentation describing its use? Reading about cold boot attacks on Wikipedia makes me think TRESOR ...
1
vote
1answer
333 views

How to export a private PGP email key

I have made a keypair for my email address using gnupg. I thought that I should probably keep a backup of it so that if I lose my desktop computer I can continue using the same key. Is this the ...
0
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1answer
216 views

Intruder nature detection by opensource tools like tripwire

I want to use different kind of intrusion detection tools like OpenSource Tripwire. Please suggest me some tools which can provide me some additional information to that provided by tripwire? ...
2
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2answers
79 views

Checking integrity of my server data

I want to make a log to detect the nature of intrusions into my Unix/Linux based server. For that I want to learn some tools like Open Source Tripwire and OSSEC. Please suggest to me similar tools. ...
2
votes
1answer
2k views

Is there a way to report incorrect login attempts in Ubuntu 12.10?

I am concerned with some people trying to access my laptop while I am away in my work place. Therefore I was wondering if is there a way to set up kind of automatically monitor and report wrong ...
3
votes
1answer
1k views

How to replace setuid with file-system capabilities

Inspired by this question here is the follow-up: As some of you may know setuid-binaries are dangerous, since some exploits use these to escalate their rights up to root. Now it seems that there has ...
2
votes
1answer
142 views

is it secure /not dangerous to ssh with keys through public transparent proxy?

I use pub key for ssh. Is it normal practice to connect to own server through public proxy? I think with plain pass it is surely dangerous but how about RSA keys?
5
votes
3answers
2k views

Stracing su and ssh shows the password. Is this a security flaw or am I missing something?

I'm currently fascinated by strace so, being new to it, I decided to play around a little. As suggested by the question title, I tried both strace su and strace ssh. Both commands displayed the ...
4
votes
3answers
1k views

rsync server/daemon security

I have a NAS (Netgear Readynas NV+) at home and a linux (Arch) box at work that is always on. The linux box is already running an ssh server/daemon and the NAS is already running an rsync ...
2
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0answers
221 views

How many rings does OpenBSD use?

Usually a Windows/Linux operating system uses afaik max 2 rings But how many rings does OpenBSD use?
3
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1answer
3k views

How to ensure that anonymous FTP has been disabled on a Solaris 10 system?

What line in which configuration files in the /etc/ftpd directory do I have to check to ensure that anonymous FTP has been disabled? From my understanding now, to ensure that anonymous FTP is ...
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0answers
94 views

Running Tomcat MySQL and Apache under a group

I am trying to set up a web server at home using Ubuntu, but prefer my bash scripts to be platform agnostic hence why I am asking here. I also dislike apt-get everything. I am trying to create a ...