Securing Linux systems and applications; understanding Linux security features.

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3answers
594 views

What is the most secure way to set up web server user permissions? [closed]

The default Debian way of setting up a common web server (Nginx) is to run the main process as root and unprivileged workers as www-data. In order to allow for the worker processes to read/execute web ...
2
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3answers
363 views

Is there an internal equivalent to fail2ban?

fail2ban is a protection against brute-force that locks a user out after a definable maximum failed login-attempts. But if a user already has access to a server with another username already fail2ban ...
5
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2answers
3k views

Best way to allow sudo access when using ssh keys

Probably a simple question, but I can't seem to find any actual best practices out there. I manage a handful of servers and I am really getting sick of tracking my passwords in pwsafe. I've been ...
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0answers
152 views

Tools to perform benchmark of block/stream ciphers on Linux? [closed]

I would like to perform some benchmarking of different block and stream ciphers for general data (lossless and lossy data) encryption and decryption (with focus on power consumption). To get general ...
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1answer
561 views

Afraid about SSH on my Linux system

I've checked my Linux server (Centos 6) with rkhunter. I found the following in rkhunter log [14:38:54] Checking if SSH protocol v1 is allowed [ Warning ] [14:38:54] Warning: The SSH ...
1
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1answer
220 views

SSH authorized_keys

Can you correct me on this. I create a keypair on my PC. Copy the public key (append to authorized_keys) on the server. Disable password auth on the server, and SSH to server from my PC. I have ...
1
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1answer
80 views

Securing WebHosting Shell Access

If I provide SSH access to users who has paid webhosting service, what security measures should be applied ? What I can think of: SSH keys RSA of 4096 size (shall be secure for a while) Apache ...
5
votes
1answer
119 views

How is using acces() opening a security hole?

The man page for access(2) tells : Warning: Using access() to check if a user is authorized to, for example, open a file before actually doing so using open(2) creates a security hole, because the ...
2
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3answers
2k views

Alternative to AirPcap for Linux?

I need to sniff WiFi packets, but according to AirPcap FAQ page, it just supports Microsoft Windows, not other platforms. Does any alternative of this product work in Linux? Please don't offer Alfa ...
3
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2answers
885 views

Alternatives to SELinux and AppArmor?

With SELinux developed by NSA and AppArmor by Novell [*], what alternate solutions exists when trying to lock down a system and running applications, based on ACL and similar concepts like Zones on ...
2
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2answers
351 views

Apparmor system-wide security — white-listing

I want to only white-list applications that can run on my system using Apparmor, I know it is used to confine applications/programs based on their path names, but what I need is to contain those ...
6
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2answers
5k views

How trustworthy is SELinux? [closed]

Given the ongoing leaks concerning mass surveillance and the fact that the NSA is the original developer of SELinux, I'm wondering whether that means that backdoors should be expected in there? As ...
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2answers
447 views

MAC spoofing preventing connection

I'm attempting MAC spoofing on a network I own. I'm connecting to a NETGEAR WNDR4300 wireless router from an Ubuntu Linux machine. The network uses WPA2-PSK [AES] security. Connecting to the network ...
0
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1answer
255 views

How could `iptables -F` lock me out of the server? [closed]

I was just configuring IPtables and whilst doing so, had the default chain policies set to ACCEPT, but when happy with the generated rules I changed that to DROP for all chains. I did not run ...
7
votes
2answers
342 views

Is there any Linux distro or kernel patch that wipes a process memory space after the process exits?

An application runs on an embedded battery-powered PC, accessible to some restricted public, that stores secrets in RAM. To prevent cold boot attacks and that the PC is stolen to extract its secrets, ...
11
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2answers
1k views

RdRand from /dev/random

"Linus Torvalds, in response to a petition on Change.org to remove RdRand from /dev/random, has lambasted the petitioner by called him ignorant for not understanding the code in Linux Kernel. ...
6
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2answers
728 views

Can i compare linux user permissions without root access?

I've compromised two Linux user accounts on a RHEL machine (neither of which have root permissions) and I want to determine which account is more 'useful' to me in terms of access and privileges. Is ...
0
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3answers
823 views

How to find vulnerable sites on a web server

A client of mine has a managed VPS with dozens of websites on it, maybe even hundreds. Now his server keeps getting infected on a regular basis. The webhost / server admins keep digging in the dark. ...
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1answer
230 views

If someone downloaded 600GB , can that be ddos attack [duplicate]

Last night some one exploit some vulnerability in my site and then upload php script in my images folder . I have the Amazon EC2 server with centos. Now the Hacker downloaded 600GB and increased my ...
0
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1answer
985 views

Using Volatility Framework with Linux memory dumps

I am using Volatility Framework 2.2 to anlayze a Linux memory dump. This memory dump was taken from an Ubuntu 12.04 LTS x86_64 machine with the kernel version 3.5.0-23 I have the profile for it and ...
15
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3answers
907 views

Why doesn't Linux randomize the address of the executable code segment?

I've recently been learning about how ASLR (address space randomization) works on Linux. At least on Fedora and Red Hat Enterprise Linux, there are two kinds of executable programs: Position ...
1
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1answer
304 views

How to authenticate to racoon with a certificate chain if only the root CA is known

I'm trying to setup IPsec using x509 certificates on Linux. I'm using racoon for that task. I've come to the point where the authentication works fine if I keep every link of the certificate chain on ...
5
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4answers
304 views

Is Encrpyting Home Sufficient?

I currently have a fully encrypted Windows System, and I'm looking at switching to Ubuntu. Is encrypting my home directory (with ecryptfs) sufficient? On windows this would be problematic due to ...
0
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1answer
262 views

Would adding root to a group open a security hole?

I have a server for which I have created a cron job "sendalerts" to users. Mind you this "sendalerts.php" should be runnable from two methods (via browser and also via a cron job) So cron's job is to ...
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votes
2answers
9k views

Why do some people think Linux is more secure than Windows? [duplicate]

I have no idea if Linux is more secure than windows. I think Linux is more secure but I want to know what is going at kernel level. Somebody told me that Linux have only one main kernel and has it ...
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2answers
1k views

Java SecureRandom doesn't block? How?

I know from experience that reading from /dev/random blocks when the Linux kernel entropy pool runs out of entropy. Also, I've seen many articles and blog entries stating that when running on Linux, ...
2
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0answers
97 views

Shorewall stopped policies - routeback

Here goes a very specific question about the insides of Shorewall and Iptables in general. Shorewall supports configuration of "Stopped Policies" using the file routestopped, which defines the ...
0
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3answers
1k views

Security checklist for hosting a website on dedicated server - Linux [closed]

I have been searching for a while now. But i can't find a start-up and advanced sought-of checklist to understand the most important things to consider while going for dedicated hosting server for a ...
2
votes
1answer
191 views

Preventing access to file for process running as root

I have a client with a legacy application running on RH 3 (=the latest version supported by app). There is a process that has to run as root (and not in a chroot environment). I need to prevent this ...
0
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2answers
220 views

Danger in opening spam emails on Ubuntu operating system [closed]

Some emails are suspected to be viruses; Because of that, the email service store categorizes them as spam. Or some pages are suspected to be viruses, and new browsers classify them as harmful pages. ...
0
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1answer
118 views

What risk does EC2/Ubuntu User-Data pose

The cloud-init Ubuntu package accepts something called user-data to configure a machine in the cloud (eg EC2 on AWS). I think AWS also use this for their Amazon Machine Image. My question is. What ...
6
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2answers
438 views

buffer overflow attack scripts

I saw various different scripts for a buffer overflow attack. Many of the scripts include lines that look like this: char code[] = "\xdb\xd7\xd9\x74\x24\xf4\xb8\x79\xc4\x64\xb7\x33\xc9\xb1\x38" ...
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0answers
137 views

Bootstrapping an EC2 Spot Instance

I'm considering using EC2 Spot Instances in an automated fashion (ie create a script that will request EC2 Spot Instances that will run unattended). For this specific use case, I'm happy to lock down ...
3
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1answer
137 views

SNMPv2 and Community Security

When working with servers on the internet and doing monitoring is there any dangers using SNMPv2? I am working with observium and have the following: /etc/snmpd.conf com2sec readonly default ...
2
votes
4answers
157 views

Protecting IP on a remote server

Apologies in advance if this question is a bit vague. I just joined a stock trading group. A guy set up a server for me, and it's racked in their building. I ssh into it, and run my algo remotely ...
3
votes
2answers
677 views

possible exploits through avahi daemon

It is always recommended to disable Avahi daemon, for security reasons, when not in use. So, by what ways it is possible to exploit a system which has avahi daemon service running? And how can we ...
5
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2answers
5k views

Ubuntu LVM Encryption

I recently installed Kubuntu and I noticed the option for having an encrypted LVM. The behavior suggests it's full disk encryption since I need to put in a password before I can boot. This article and ...
3
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1answer
840 views

How to remove ssh rootkits? [duplicate]

I checked my linux server with rkhunter, I got following warning messages, ... [00:35:35] Found file '/usr/include/gpm2.h'. Possible rootkit: Trojaned SSH daemon [00:35:35] ...
0
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1answer
646 views

How do I generate a blowfish password hash in Ubuntu?

What's the command line to generate a blowfish password hash? I can't seem to figure this out at all. Apache's htpasswd only supports bcrypt, and openssl passwd doesn't even do blowfish hahes (but it ...
25
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6answers
3k views

Most secure way to partition linux?

I recently acquired a netbook to play with, and I want to install Kali Linux so I can start learning about network security and exploit development. I want to use this to learn as much about security ...
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votes
4answers
538 views

How can I use linux and disguise myself as a windows computer over a LAN? [closed]

My computer is currently running windows XP on a LAN Network. I'd like to use linux but I want to hide myself. I don't want to be the only linux system on a network full of windows XP computers. Is ...
1
vote
1answer
251 views

Small encrypted network setup [closed]

Several partners and I have just started a small business and we would like to employ a good secure setup from day one. This is a problem however as there are many piecemeal packages, and I am stuck ...
2
votes
2answers
569 views

Linux Memory Protection from buffer overflow

I am practicing Linux buffer overflow exploitation. when trying to exploit a vulnerability in crossfire, everything works well and I get the shellcode placed in the right place, and the program flow ...
1
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2answers
526 views

Centralize Linux System Management

We currently maintain several linux servers and are looking to employ sub contractors. However, we wan't to keep tabs on who does what on each server. Other then creating sudo accounts on every ...
-1
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1answer
408 views

mprotect at kernel level

What would happen if a kernel-level process sets some of its memory pages as PROT_NONE with mprotect and another kernel-level process tries to read one of these protected pages? What is the ...
2
votes
3answers
337 views

Encrypting Backups on Linux

I'm working on an automated backup solution to protect my files on my Linux servers. However, I'm not sure about how to securely encrypt the resulting archives. I am using 64bit linux, and I am ...
2
votes
2answers
735 views

How to protect Linux partition from access from Windows partition?

In a dual-boot environment (windows? and linux mint 15) What would be best best way to prevent access to the linux partition(s) when the system is booted into windows 7? The goal would be to ...
1
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5answers
1k views

Encrypt-function inside PHP code that you have to publish

If you write a PHP application, where you have to deliver the compiled code to the customer, how could you include a functionality to send encrypted data from that application to others, and include ...
2
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2answers
469 views

Mixing stateless and stateful firewall rules

I have been advised that mixing firewall rules that are both stateful and stateless can lead to trouble when it comes to troubleshooting. Is there any truth in this? Take the following two rule sets ...
5
votes
1answer
628 views

Are Linux vendor-supplied security updates enough for PCI Compliance?

I have several systems that require PCI compliance, all of them are running CentOS 6.4 with all security updates applied daily. However, PCI compliance scanning will often reject detected versions of ...