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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apply proper security labels during filesystem restore

When restoring a filesystem on a separate system (i.e., possibly a different system than the one where the filesystem was originally mounted and in use), I would like to apply the correct security ...
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7 views

How to set usb stick's ntfs filesystem's attribute to readonly in linux

I know how to set readonly attribute to ntfs filesystem of a usb device by using diskpart tool in windows. attributes disk set readonly but how to set readonly attribute to the same usb device ...
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11 views

What are the minimal MySQL grants for the debian-sys-maint user?

What are the minimal privileges that debian-sys-maint@localhost needs for the mysql service to work correctly? This answer on ServerFault suggests granting RELOAD only, but this is incorrect, as it ...
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1answer
18 views

How to reinstall the password of Grub?

I have Debian 8 OS , i protect my grub with a password to prevent the boot from a CD and retrieve my password. And the automatic establishment of the recovery entry is removed. Is there a solution to ...
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1answer
17 views

LXC: Are downloaded templates verified?

Debian 8.3, LXC 1:1.0.6-6+deb8u2 When LXC downloads the base packages for a Debian container, are the packages verified? Verifying a Debian CD involves comparing signed checksum files against the ...
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1answer
19 views

Creating Encrypted Tunnel Between 2 Lans

I have 2 LANs and one of them is connected to the internet and I need to connect them together. Normally, a single cat6 cable is enough for connection however, this cable is going through a public ...
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4answers
2k views

What happens when a non-root user sends signals to root user's process?

I'm wondering about the security of UNIX signals. SIGKILL will kill the process. So, what happens when a non root user's process sends a signal to a root user's process? Does the process still ...
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1answer
24 views

Linux TOTP vs SSH Keys

I am in the middle of a security upgrade task and have been reading a lot of articles around SSH security. I have a question around what is the better method of securing SSH by using SSH Keys or TOTP? ...
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2answers
86 views

Debian Lenny Server Compromised - No Sign Of Intrusion Point?

I have a server, it's outdated running Debian Lenny, and yes I know that is probably half the problem. It also has PHPMyAdmin and ProFTPd. Again, I get it, all bad signs. But for the life of me, I ...
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0answers
24 views

SSH/web servers in Linux containers improve security?

Scenario: A 'gateway' machine functioning as a router and firewall, connecting a small LAN to the internet. The machine also runs a webserver (hosting a simple website) and an SSH server, providing ...
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1answer
16 views

Reassemble images forwarded though Linux router?

In 2003-2004 I used a Linux app that reassembled images from HTTP traffic forwarded through a Linux router, displaying them live. Just a command line app that threw up an X window, showing the images ...
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1answer
19 views

fail2ban ip blocked, yet still login attempts

everything seems ok, iptables shows its blocked, yet I still get auth attempts I have configured fail2ban # "ignoreip" can be an IP address, a CIDR mask or a DNS host ignoreip = 127.0.0.1/8 bantime ...
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2answers
39 views

Need the sshd server be run in root privilege for a password-less login? [closed]

I mean: if the sshd is't being run in root account, then how can it let the remote ssh client run shell or other command in root account ? if sshd call the login command, then the user could login ...
4
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1answer
64 views

Linux Mint: pastebin is in /usr/local/bin

I'm running Linux Mint 17. I found a pastebin python file in /usr/local/bin In light of what people use pastebin for, was this a security risk? Output from the stat command: File: ‘pastebin’ ...
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4answers
101 views

Why does mknod require root privileges?

I noticed that the mknod command required root privileges when a creating a node other than a regular file, FIFO or a Unix socket. Why is that? How can a regular user harm a system or compromise ...
4
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1answer
32 views

Is libvirt dnsmasq exposed to the network, if I run Fedora without a firewall?

There's this nice saying from Ubuntu: no open ports on the default install. Other Linux OS's look the same, including Fedora. No-one wants to worry about firewalls, if they don't need to. Yuck, ...
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1answer
26 views

What are the drawbacks of using policy_any in openssl.cnf?

As given in this document, we may use policy_any to ignore most of the fields of subject in certificate request. There must be some drawbacks of ignoring such fields, would it may lead to some ...
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3answers
47 views

What additional privileges does the root user have over a standard user? [closed]

What additional privileges does the root user have over a standard user in Linux?
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1answer
24 views

Is sudo useful to protect my data from malwares?

I'm considering creating a separate account for browsing, and launching my browser with sudo -u browseraccount {firefox,chromium,etc}. I wonder if this can prevent a malware (especially ransomwares) ...
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2answers
54 views

Is it evil to link to a crontab?

I think about doing something like: sudo ln -s ~/myCustomCrontab /var/spool/cron/crontabs/username because I'd like to have all customized files in my home directory. Possible risks I can think of ...
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6answers
5k views

Why does reboot and poweroff require root privileges?

To restart or shut off Linux from the terminal, one can use reboot and poweroff, respectively. However, both of these commands require root privileges. Why is this so? What security risk is posed by ...
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1answer
51 views

What are the right permissions to set to make files unreadable unless it's my main user accessing them?

Basically I didn't encrypt my Linux (Debian) partition when installing it. However I found a way to encrypt at least home folder so in theory I could put everything there which I want to make sure ...
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0answers
35 views

Is insecure to give users permissions to apps in /opt? [duplicate]

I'm working with some apps (the best example i can give is Firefox Developer Edition) that i put in the /opt folder. These apps work perfectly until they need to apply and update, and that's because ...
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0answers
51 views

Does running fcgiwrap with nginx give the same added security as creating a new php-fpm pool for every site by hand?

Here's the nginx + fcgiwrap configuration I'm talking about. I don't understand what the main differences are between this kind of a fcgiwrap configuration and a nginx + php-fpm configuration. They ...
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21 views

How to get informed about EVERY incoming ssh connection (e.g. with no remote command specified)

The case I'm used to set up automatic reverse ssh tunnels to remote computers via my server with cron. Usually I use the following entry: @reboot sleep 300 && ssh -MNf -R xxx22:host:22 ...
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1answer
17 views

Hide/Encrypt application configuration

Is there any way to hide/crypt software config files (services such as Apache web server , Varnish and so on) from boss and others?
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0answers
15 views

dirmngr does not start with proper home directory unless it is restarted

I am trying to follow these guidelines for gpg best practices: https://help.riseup.net/en/security/message-security/openpgp/best-practices but I am having trouble with dirmngr, which handles all ...
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1answer
24 views

Can't access web sites when running iptables script!

I have wrote script for protecting my machine: #!/bin/bash ssh=1.1.1.1 http='1.1.1.1 2.2.2.2' # Clear any previous rules. iptables -F # Default drop policy. iptables -P INPUT DROP iptables -P ...
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1answer
31 views

How to protect from chrooting to its linux partition and how to chroot it after using the protection?

I am currently using archlinux, It is possible to boot on an archlinux installation iso for instance, to mount my current archlinux partition and my boot partition and then to use arch-chroot. Then I ...
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1answer
39 views

Managing iptables for specific ips and ports

I disable firewall like so: #!/bin/bash iptables -F iptables -X iptables -P INPUT ACCEPT iptables -P OUTPUT ACCEPT iptables -P FORWARD ACCEPT Update I also enable my firewall: #!/bin/bash ...
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2answers
39 views

Storing application passwords in central location

Is there any secure local service that one should use for storing and retrieving organization wide application passwords? Most of the time we need authentication information in our scripts to run some ...
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0answers
12 views

Need Help to Solve Screenlock Bypass Issue for Expired User Account

I have created a script that I deploy to my children's computers via Salt. The script implements allowed working hours and has worked well, but one of my children have found a way of bypassing this ...
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1answer
19 views

How does JetBrains PyCarm IDE put files into directories outside of ~/ despite being run without sudo?

PyCharm is a lovely Python IDE by JetBrains that can be downloaded here. I have downloaded the free community edition, extracted (with sudo) it into /opt/jetbrains/pycharm and run (without sudo) ...
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0answers
19 views

How to view WIFI devices names and signal strength [duplicate]

I want a cli utility or script that shows all the Wifi devices or hotspots or access points and their signal strength. I want to log this data using Python. I will write the logging script myself. ...
0
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1answer
52 views

How would pressing backspace 28 times break Grub2 [duplicate]

I just came across this article about how pressing backspace 28 times on the grub screen. Since most mainstream media just says this happens, I've been unable to find anything that explains how it ...
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1answer
37 views

How to track who added sudo privilege to a user

I have a LDAP user named "ciadmin" created on the Red Hat based system without sudo privlidges. Somehow this user now has sudo privileges and can basically become root on the system. I want to track ...
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1answer
31 views

Is there any concrete risk involved in using the same password for root, kde wallets and key rings?

To make it easier I decided to use the same password for root (su(do)), kde wallet (KDE desktop) and keyring(s). No one has access to this password in "real world" (given that the computer is ...
3
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1answer
22 views

Monitoring ports on ongoing connections

I have a vps server that is blocking me every hour via ip with its firewall. Looking the logs several messages like these where found: Dec 16 13:52:08 srv kernel: [17226167.610181] Firewall: ...
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2answers
47 views

set up secure connection over SSH

I'm setting up a server application which requires to establish a secure connection over SSH2, e.g. a client must open SSH2 connection to the server to reach specific application: % ssh -s -p5000 ...
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0answers
16 views

Benefit of using multiple checksums for a group in AIDE

What are the benefits to having all md checksum functions specified for a group when running AIDE? For example, what is the difference between defining the first line and the second line with less md ...
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1answer
34 views

ARP Spoofing in Data Center

I have a dedicated root server. I noticed strange connections from 255.255.255.255 in iftop. Because of that i tried to investigate it. I runned the following command: tcpdump -i eth0 ether ...
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0answers
43 views

Block IP Fragmentation attack using iptables

I am trying to stop all MF flag packet which has more fragment big set. because i have seen many IP Frag attack taking advantage of it. I know its not a good idea to do but, I have test my application ...
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0answers
15 views

How can I encrypt disks in Mint-17 without destroying the data

I have a mint-17 machine with 2 disks managed through lvm. I would like to encrypt the disks. I need to keep the data/apps intact. Is there a way in mint if I could just encrypt the drives or ...
4
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0answers
51 views

How come I can login to another person's session over vnc just by changing the port number?

I have a user account on a server administered by someone else. I don't have root access. The server is CentOS 7. I couldn't connect over vnc on the usual port I use, so I ssh'd into the server and ...
0
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0answers
31 views

When have software mirrors been compromised before?

Stemming from this answer Mirrors can be compromised (this has happened in the past). It's easier to watch a single distribution point. If an attacker managed to upload a malicious package ...
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1answer
177 views

Help With PulledPork Please

I have been working to get snort, barnyard2 and pulledpork installed on my Ubuntu machine, and I have the 1st two installed not problem. With pulledpork I cant seem to get past this error message: ...
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2answers
46 views

Is UFW behind a firewall(ed) gateway router necessary

Is it really necessary to run UFW behind my Gateway Router which already has Firewall/Port rules? In this example, I am discussing running UFW on an Internet Accessible (Linux) Server that is behind ...
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1answer
16 views

Value of nmap option

I've found in some docs of port knocking, that it is used the option --host-timeout I don't understand why is 201 assigned to it? e.g.: nmap -Pn --host-timeout 201 --max-retries 0 -p 7000 ...
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1answer
299 views

Why does ArchLinux keep some users/groups after package uninstallation?

I've noticed that after uninstalling the postgresql package in ArchLinux the postgres user and group are not removed automatically. The same is true for some other packages. Investigating this ...
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2answers
79 views

What kind of data is stored in the ext4 file system's journal?

The ext4 file system has a feature called has_journal. In the dumpe2fs output, we can see something like this: # dumpe2fs /dev/sda2 | grep -i journal Journal inode: 8 Journal backup: ...