Unix & Linux Weekly Newsletter - Tuesday, March 29, 2016

Top new questions this week: Vulnerability demonstration on Ubuntu 9.04 For a class on IT security, I want to demonstrate privilege escalation to the students. To do so, I looked through the exploit/linux/local list in the Metasploit Framework, finding (among others) ... / ubuntu / security / privileges / metasploit   asked by Andreas Unterweger 13 votes answered by terdon 14 votes Does crond handles summer time +1 hour change? Last weekend we had to change the time from 02:00 to 03:00. Question: What would happen if there was a cronjob at 02:30? crond is a very old solution for scheduling, it should probably handle it, ... / cron / daylight-saving-time   asked by LoukiosValentine79 11 votes answered by Anthon 12 votes Root shell mistakenly changed. How can I change it back to a valid shell? I mistakenly entered chsh -s /usr/bin instead of chsh -s /bin/bash and now I can't log into a root shell, how do I start a bash shell as root manually ? / bash / shell   asked by ChiseledAbs 11 votes answered by Rui F Ribeiro 22 votes Shell variable $_ not behaving as expected What the reason the number of lines differs? $ head -n 100000 ./access.log > ./data/log.sample $ cat $_ | wc -l 1933424 / bash / io-redirection   asked by Loom 9 votes answered by heemayl 25 votes Finding the source of CoW page faults on OS X I'm trying to find the source of CoW page faults in some C code on OS X. I would like to use the vminfo DTrace provider, but vminfo isn't available on OS X. On Linux, I can use SystemTap to print a ... / memory / dtrace   asked by Aaron Patterson 5 votes answered by bahamat 0 votes Can I get SSH to use an askpass program even if it was run from a terminal? man ssh says: SSH_ASKPASS If ssh needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If ssh does not have a terminal associated with ... / linux / ssh / openssh   asked by muru 5 votes answered by Jakuje 5 votes Regarding the creation and destruction of sensitive data on linux/unix systems In modern file systems (and on modern SSDs) there is no guarantee that if you write over a file using a traditional utility (such as dd) that the data will be overwritten in-place and journaled ... / linux / tmpfs / ramdisk / data-destruction   asked by Schives 5 votes answered by Bogdan 3 votes Greatest hits from previous weeks: How do I set my DNS when resolv.conf is being overwritten? Most of the info I see online says to edit /etc/resolv.conf, but any changes I make there just get overridden. $ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by ... / linux / ubuntu / networking / dns / dnsmasq   asked by Seán Hayes 94 votes answered by Seán Hayes 14 votes List all connected SSH sessions? I just SSH'd into root, and then SSH'd again into root on the same machine. So I have two windows open both SSH'd into root on my remote machine. From the shell, how can I see a list of these two ... / ssh / terminal   asked by themirror 52 votes answered by jayhendren 57 votes Can you answer these? How would I limit users' sudo permissions for journalctl to a specific unit? I want to provide our users access to journalctl of a specific unit. For e.g., httpd. My initial thought was to specify the command spec like this: /usr/bin/journalctl -u httpd.service * This will ... / linux / sudo / systemd / journald   asked by Belmin Fernandez 2 votes Reboot takes too long I have a Toshiba S55-B5280 which originally came installed with Windows 10 and after a while I decided to go with linux and try to install it. My choice was Manjaro Linux and so far it has work well ... / reboot   asked by Nelson Miranda 2 votes Why does `ping -M do -s 8000` still work between hosts with different MTU values? I have two hosts: alice (192.168.0.1, mtu 9000) bob (192.168.0.2, mtu 1500) They are directly connected with a cat 6 cable, with no switch in between. Why is it that I can still ping bob from ... / networking / network-interface   asked by Kal 2 votes

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