Securing Linux systems and applications; understanding Linux security features.

learn more… | top users | synonyms

0
votes
1answer
347 views

Stack Guard vs Stack Shield

I would like to know why nowadays Stack Guard is used everywhere (example: ProPolice in GCC, /GS in Visual Studio), instead of Stack Shield. Both the approaches (i.e. Stack Guard & Stack Shield) ...
17
votes
3answers
34k views

What is the difference between authorized_key and known_host file for SSH?

I am learning basics of SSH protocol. I am confused between the contents of the following 2 files: ~/.ssh/authorized_keys: Holds a list of authorized public keys for servers. When the client ...
6
votes
3answers
500 views

Security of the KWallet password encrypting application?

According to http://gaganpreet.in/blog/2013/07/24/kwallet-security-analysis/ , the KWallet password management system is quite weak, it uses key splitting, Blowfish 56, and no salt. The key ...
7
votes
5answers
793 views

Securing Debian Apache PHP Server

I have Debian Apache PHP server. I want to secure him after the classic installation process. My usual steps are : List item update all packages remove all unnecessary services like named, portmap, ...
0
votes
1answer
208 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 ...
-1
votes
2answers
139 views

Linux: Blocking outside attempts at attacking computer

in the past when I wanted to block outsiders from attempting to start connections with my Linux machine's various TCP services, what I was told to do was to add this line to /etc/hosts.deny: ...
4
votes
1answer
909 views

What tools can be use for Security Auditing for Redhat

Are there any good tools that can be used for Security auditing of Redhat Linux. That can audit all the critical areas of System and provide the detailed output of all the audited sections.
2
votes
3answers
224 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 ...
4
votes
2answers
1k 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 ...
5
votes
2answers
836 views

Securing USB flash drive on linux

We have a industrial system(running on linux) with a USB port. We have the USB port only for copying certain data. Other than this we don't want the USB drive to contain any other executables or ...
-1
votes
1answer
449 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 ...
2
votes
3answers
1k 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 ...
1
vote
1answer
203 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
vote
1answer
68 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 ...
14
votes
3answers
549 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 ...
4
votes
2answers
1k views

Can you have 2 promiscuous (sniffing) ports on a single machine?

I'm wondering if you can actually have 2 (or more) promiscuous (sniffing) ports on a single machine, to monitor multiple network segments? And can you monitor them all with snort?
8
votes
3answers
3k views

Is CentOS a good choice from a security perspective?

How secure is the CentOS Linux distribution? I noticed there were times when there were no up-to-date patches for some version of CentOS (e.g., 5.6). I read this on some mailing list that I can't ...
3
votes
2answers
3k 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 ...
4
votes
1answer
405 views

Can auditd track events that occured over NFS

I have multiple servers mounting a NFS shared called /opt/WHATEVER from Server X. Server X has auditd enables with rule: sudo /sbin/auditctl -w /opt/WHATEVER -p rwxa When events occur on Server X ...
10
votes
1answer
2k views

Backtrack 5 in a VM - Why bridged networking over NAT?

When running Backtrack 5 from a VM, it is recommended to use the bridged networking option instead of the NAT networking option? How does it affect the usage of Backtrack - port scanning, ...
1
vote
2answers
342 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 ...
4
votes
2answers
224 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, ...
9
votes
7answers
1k views

How are open-sourced operating systems and software kept secure?

I have been wondering about his for awhile. I have Linux running on a PC at home. I had a jailbroken iPhone. They both have attributes that make them very attractive, and they are also FREE! But I ...
0
votes
1answer
171 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 ...
6
votes
2answers
528 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
votes
3answers
759 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. ...
-1
votes
1answer
182 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 ...
1
vote
1answer
222 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
votes
4answers
234 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 ...
12
votes
5answers
932 views

Can a .sh file be malware?

Can a .sh file be a virus or something harmful? Is it like .exe files on Windows? If yes can someone read this script and tell me if it safe and is it effect any how on gpg security. It gives me an ...
-4
votes
2answers
6k 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 ...
61
votes
3answers
7k views

Is a rand from /dev/urandom secure for a login key?

Lets say I want to cookie for a user, would simply going to /dev/urandom, generating a 1024 bit string, checking if it already exists (and looping till I get a unique one) suffice? Or should I be ...
24
votes
6answers
2k 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 ...
2
votes
0answers
78 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
votes
3answers
832 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
146 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
votes
2answers
171 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
votes
1answer
86 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
votes
2answers
368 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" ...
4
votes
1answer
486 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 ...
4
votes
3answers
2k views

How to scan USB drive with clamav on Linux

Is there a way to scan the entire drive including auto-run and all partitions, including the master boot record (MBR)?
2
votes
0answers
81 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 ...
2
votes
4answers
140 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
1answer
78 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 ...
3
votes
2answers
430 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 ...
4
votes
2answers
3k 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 ...
2
votes
2answers
235 views

Can unencrypted keys & logins be kept out of program memory?

No matter what technique is used to store encryption keys & logins, it seems that all roads lead back to program memory (as far as I know), as an unencrypted version of the keys & logins will ...
3
votes
1answer
591 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
votes
1answer
468 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 ...
-5
votes
4answers
348 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 ...