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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unix system with malware

I have a CENTOS server that is infected with malware: top shows there's an unknown process that's consuming all the CPUs, if you kill it, it respawns with a different name. what's the best way to ...
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6 views

kernel security and IDS Firewall + AV together or not?

I try to hardening my server. For doing so, I got a general question: Should I install kernel security patches like selinux and an Anti-Virus with Intrusion Detection Firewall? Does it make sense to ...
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0answers
13 views

When running 'su - username', pam_group doesn't add additional groups from /etc/security/group.conf but sshd login does?

I am having trouble determining why su doesn't behave as the PAM configuration would imply. In short, using su to become another user should load secondary groups according to PAM configuration, but ...
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2answers
96 views

Run Ubuntu Security Updates every Saturday only

A clients wants to enable automatic security updates on their 12.04 box, but it has to be once per week, on saturday only. (Why I don't know) When I do dpkg-reconfigure -plow unattended-upgrades it's ...
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1answer
29 views

NIS and /etc/passwd

Shadow passwords are to be avoided in a NIS server, as suggested in this guide at paragraph 7.6. So: in a NIS server (a Unix or Unix-like system), should all the users be migrated to /etc/passwd from ...
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1answer
1k views

Can another program on X capture my root password while I type it in a virtual terminal?

Usually I only install open source programs on my linux box because I don't trust closed source applications. Recently I had to use Dropbox for a university project. I created a separate linux account ...
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1answer
13 views

How to restrict restrict remopte administration software to one domain name?

I currently have a server hosting a number of website on a debian server. I understand that all my domain names share the same IP so any of them will grant me access through SSH, but i was wondering ...
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1answer
32 views

How to run unattended-upgrades not daily but every few hours

By default unattended-upgrades runs with cron.daily, that is at most on a daily basis. This can be a lot of time for attackers. I'd like to run it every 4 hours, how can I do this?
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31 views

Finding out if my system is being used as a bot by looking at ifconfig?

Recently, I have often been suspicious that my router (a linux box) might have been used as a bot for spam blowout or something of that quality because I may have misconfigured my iptables rules by ...
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1answer
87 views

RHEL 7 (CentOS 7) security / ssh / sshd_config advise requested

I am not a sysadmin and try to create a more or less secure web server (LAMP based CentOS 7). I read several tutorials about setup an initial CentOS 7 droplet and got everything running fine. ...
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11 views

Secure mailing [open panel]

I'm a total noobie in the security subject, and I'm not sure what it really takes to have a secure mailing service. I've installed Open panel, which has postfix (among other services) mailing server. ...
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1answer
49 views

What considerations would I need when configuring iptables?

Synopsis I am looking at learning more about Server Administration. I have been running my own web server for a few years although many things were set-up by my friend and now I wish to learn more ...
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40 views

Sudo User: Not able to see the home directory of other users

I created sudo user hrsupport with following commands: hrsupport ALL=ALL, NOPASSWD: /bin/chown, /bin/chmod, /bin/chgrp, /scripts/pkgacct, /scripts/restorepkg How can I achieve this The hrsupport ...
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3answers
34 views

/etc/passwd permissions and GECOS field

The default permissions on Ubuntu (or even some BSD) distributions for the /etc/passwd file are 644. It is pointed out in questions like this that /etc/passwd is a sort of user database and it is ...
6
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2answers
52 views

Linux graphical password dialog trick security

When we run a command by sudo, the password is asked [sudo] password for user If the sudo is not typed the password should not be asked. If asked, I would assume it as a fraud by the application. ...
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0answers
19 views

How do I securely automate inputting passwords?

I would like to automate an SSH connection so that I wouldn't have to enter password and I am not allowed to use authorized_keys. I was thinking about making an expect script but I don't know where I ...
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0answers
20 views

Network Manager losing saved vpn passwords in Mint 17

my vpn is setup in the network manager, and the passwords are saved in there. however, those passwords are disappearing, they will be there for several days, and then be gone. what could be causing ...
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1answer
28 views

Protecting process's envvars from exposure

From I've read about current best practices for developing web applications (such as the Twelve Factor guide), the recommended approach for storing configuration data is within environment variables. ...
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4answers
59 views

How can I lock myself out of a linux box with iptables?

In the Securing Debian Howto I read (about iptables): The tools can easily be misused, causing enormous amounts of grief by completely crippling network access to a system. It is not terribly ...
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1answer
21 views

What if I add a user to a supplementary group?

I am using debian 7.0 and I added "debian-transmission" to the group "pi" with: usermod -a -G pi debian-transmission I made this change because transmission was not able to write the pi mounted ...
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1answer
44 views

blocking all but specific ips from specific services in CentOS 7

In a CentOS 7 web server that needs to remain totally closed to the public, I need to block all ip addresses and then only allow specified ip addresses to access specified services. How can I ...
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3 views

Help hooking sys_recvmsg to hide a socket from ss (educational rootkit) [migrated]

My question is this. After hooking, finding the nlmsghdr structures, finding the inet_diag_req structures, I change the port number in a inet_diag_req struct (to 56666). Then copy the message from ...
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0answers
17 views

List all files with only arbitrary file path read, but no directory listing nor sudo [migrated]

I have found a path traversal vulnerability that allows me to read any path on the server that does not require sudo. To fully exploit this, I would like to know which files exist in each directory ...
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17 views

httpd and mod_security woth OWASP's dos rules

I'm trying to setup the mod_security on my httpd web server. I have followed the basic steps yum install mod_security I put the modsecurity_crs_10_setup.conf in the /etc/httpd/modsecurity.d I put ...
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1answer
28 views

Reason for security repositories in Debian?

In /etc/apt/sources.list(lists APT data sources) file there are two repositories listed for security updates: deb http://security.debian.org/ wheezy/updates main contrib non-free deb-src ...
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1answer
58 views

Will I receive critical security updates if I lock CentOS yum to a specific repo version?

We run Citrix XenServer as our virtualisation platform. Presently we're right up to date with our XenServer service packs and hotfixes i.e. we're running XenServer 6.2SP1 with the SP1015 update ...
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1answer
36 views

Custom Kernel to Disable SATA and USB Devices

I am setting up diskless clients that will run on an internal network. I have disabled SATA and USB ports using a BIOS locked with a password, but this is easy to get around by using the jumper to ...
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1answer
25 views

what does Xserver access control mean

What meaning does Xserver access control have, when the Xserver is started with tcp disabled: /usr/bin/X11/X -nolisten tcp AFAIU, Xserver can be used to allow remote network connection. But, if it ...
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1answer
37 views

Use sudo from another programm

I was wondering it is safe or an acceptable practice to use sudo to run an application from another one. For example, Let's say I have an application that uses a configuration file to do its work and, ...
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2answers
53 views

Is system call the only way that a user program can intentionally affect the state of a Linux kernel?

I think there are several ways that a user program can intentionally affect the state of a Linux kernel. By invoking a system call; By invoking mmap() and writing the memory that has been mapped to ...
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0answers
16 views

setting up nested X sessions with Xephyr properly (and securely)

I am trying to set up Xephyr properly and securely, so that I can run another (nested) instance of LXDE under a different user inside my primary LXDE session. I would like to use this nested session ...
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2answers
33 views

How to instablock IP based on root SSH login

I have had this setup before by a friend of mine but it got lost in a reinstall. Basically what happened was, whenever someone would directly SSH to my server as root their IP would get blocked, you ...
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1answer
161 views

Some basic questions about Linux kernel's security [closed]

I don't know much about Linux kernel, and I have some questions. What is the main purpose of separating kernel memory from user-space memory? To make sure that a user application cannot do anything ...
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0answers
17 views

Initial iptable rule and knockd operation in vps

Today I launched a vps with Debian 7 x64 and started playing around with it. I installed xampp as well as knock daemon to get my hands dirty. So, all I wanted to do was to actually block all requests ...
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1answer
27 views

Disallow change of init kernel parameter

is there any way to disallow changing init parameter on boot time? I want to prevent situation when someone reboot my server, edit grub entry and get access without password. Maybe some kernel ...
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26 views

Investigate compromise on Fedora 20

I am running Fedora 20, and I just discovered that a client's server was logged in to back on October 9th from my ip address, and an erroneous ftp account was created on each of his cpanel ...
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1answer
251 views

Security Implications of using unsanitized data in Shell Arithmetic evaluation

In a comment to a recent question, Stéphane Chazelas mentions that there are security implications to double parentheses arithmetic such as: x=$((1-$x)) on most shells. My Google skills seem to be ...
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1answer
20 views

acedemic projects related to linux virtualization and security [closed]

I am B.tech student iam totally confused with the topic virtualization. but i selected linux virtualization security as a project in my college. please guide me. i tried in google but i found so many ...
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2answers
46 views

Lightweight SSH-only distro (< 128 MiB RAM) [closed]

I am looking to set up an SSH entry point into my network via a lightweight Linux or BSD setup. The purpose of the distro will be to allow SSH access into the rest of the internal network—that's it. ...
0
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1answer
438 views

OpenVAS 7 not working after apt-get update - Failed to receive data: A TLS packet with unexpected length was received

The problem started when my Kali installation updated OpenVAS to v7: My admin username for the web service stopped working so I could no longer log in. I have tried everything I can think of to fix ...
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1answer
58 views

Assp won't start

I tried to install ASSP (Anti-Spam SMTP Proxy Server),but when I try to start it I get the following: $ perl assp.pl Perl version 5.012003 (5.12.3) is at least recommended to run ASSP 2.4.3 (14313) ...
42
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1answer
951 views

Security implications of forgetting to quote a variable in bash/POSIX shells

If you've been following unix.stackexchange.com for a while, you should hopefully know by now that leaving a variable unquoted in list context (as in echo $var) in Bourne/POSIX shells (zsh being the ...
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24 views

How can I set a group policy to all access on all folders except one?

I am currently making a test environment where users will be going through a network administration course with different levels they must complete. Due to the nature of the course, we want to give ...
2
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2answers
32 views

Securely making an SSH connection from a public computer

Today, I had to remotely connect to my debian computer at home to fix an issue with a VPN server. I was using my iPhone with an SSH client to fix the issue, but I had a hard time due to the small ...
2
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1answer
72 views

enable echo service and linux security loophole issues

in order to enable the echo service we need to add the echo lines as the following example : more /etc/inetd.conf echo stream tcp nowait root internal echo dgram udp wait root ...
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2answers
212 views

Security implications of running perl -ne '…' *

Apparently, running: perl -n -e 'some perl code' * Or find . ... -exec perl -n -e '...' {} + (same with -p instead of -n) Or perl -e 'some code using <>' * often found in one-liners ...
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2answers
60 views

What does this host means ' ::1 '

To secure my mysql server, I checked the list of users : mysql> SELECT User,Host,Password FROM mysql.user; +------------------+-----------+-------------------------------------------+ | User ...
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49 views

Reading Suricata log files with Barnyard or Wireshark

I have Suricata 2.0.3 running on CentOS 6.5. It generates files that I cannot read. I have read that two options for reading the log files (in unified format) are barnyard and WireShark. I ...
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1answer
35 views

Cluster Lock Manager without TCP/IP

I have 2 linux sharing same SAN disk LUN. There are many cluster files systems to manage lock/unlock. But all of them are using a seperate TCP/IP comminication. But I need a cluster lock manager ...
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1answer
30 views

How can I go about tracking down DNS queries?

I was looking at the dnsmasq logs on a router I run and noticed that there are requests to a particular url on a regular basis. This was happening while the only client connected to the network was my ...