I already have a ssh private key without a passphrase. As I have started to use it to login to a few critical and secure systems, I need to use a passphrase on my RSA private key. How can I enable passphrase on an already existing private key? Also I want to know how to backup the private key before I enable passphrase, in case I mess up or forget the passphrase (only for some days until I can commit the passphrase to my memory).
I work on a ubuntu server located in a place where I don't usually go. I use ssh over openvpn to access it. The machine has multiple wired interfaces, many static routes and multiple default gateways to WAN. I frequently change interface adresses and routes. Most of the times the changes I do are temporarily--a reboot would reset the experiments I have done. In some cases some of those modifications have gone wrong, and the machine has gone offline. In such cases I had to call up someone at the place where the server is located to send the machine into a reboot.
Now I would like to schedule a reboot--lets say after 2 hours the machine should go into a reboot cycle. And in those two hours I can do whatever temporary experiments that I want. If all the temporary changes succeed then I should be able to prevent the "afer 2 hour" reboot from happening. So what I want is:
- How to tell the server to reboot after a certian time?
- If I decide that the machine should not go into a reboot, I should be able to cancel it.
What is the best tool for recovering deleted data from a flash drive (pen drive)?
How to enable boot messages, kernel messages and other logs of various services to be printed on screen during boot up?
I use ubuntu server 10.04 on a fairly good machine, with 2.40 dual-core processor and 2GB RAM.
My users login with ssh or samba. I have setup LDAP with PAM to sync user accounts between unix and samba. When I allowed about 90 users to login over ssh at once the server refused login for many users. I am using dropbear as ssh server. Even samba logins failed for many users. I need to allow at least 100 users to login at once. Is there anyway to do this?
I want to know if the official 700MB installation images can be used to do a network installation. What would be the easiest way to do it?
I have manually specified only ipv4 address for my interfaces. But all the interfaces automatically show inet6 address as well. Does it mean that ubuntu starts an ipv6 tunnel by default. If it does, isn't it dangerous, as ipv6 assigns public ips for all LAN clients. I only have a firewall on my NAT router, and my clients, who's interfaces show ipv6 address, do not have firewalls. Here is a screenshot:
eth0 Link encap:Ethernet HWaddr 34:dc:47:2e:ad:13
inet6 addr: fe80::28cf:38ff:fb7b:da19/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5783 errors:0 dropped:0 overruns:0 frame:0
TX packets:6098 errors:0 dropped:0 overruns:0 carrier:1
collisions:0 txqueuelen:1000
RX bytes:2961324 (2.9 MB) TX bytes:1573757 (1.5 MB)
Interrupt:46
Note: For privacy reasons I have modified the HWaddr and inet6 addr values.
The network interface should not make a request for an IP over DHCP. So, what is the command to turn off NetworkManager in Ubuntu?
Update:
I am writing a script in which the interfaces receive static IPs. For this to happen I need to put a line in the script which will turn off NetworkManager. But when I'm not using that script I want to have DHCP on the interfaces.
On my ubuntu machine, I have squid3 as a daemon which starts at boot.
The problem is that squid3 takes a long time to start and stop (more than 30 seconds) and it has also slowed down my OS startup/shutdown time considerably.
How can I solve this issue?
I want to stop some daemons from loading at boot time, specially squid3. What is the best way of doing this?
I usually provide solutions for my friends for fixing issues on their ubuntu machines. Most of them use shared internet connection over LAN where they cannot open ports for allowing me access their machines over ssh. Is it possible to ssh into a machine without opening ports. For example services like Teamviewer allow users to just accept a connection request from outside, and if the owner of the machine permits, then the machine can be used by authenticated users. So, similarly, if the owner of the machine permits, with some kind of authentication, one should be able to get ssh access to a machine without opening the ports on the NAT router.
Possible Duplicate:
How can I install software offline?
I want to download and save some deb files, and preferably their dependencies, of certain apps, from the repositories (apt-get, aptitude) to a custom location without installing, so that I can install those apps while the machine is off-line. Also I want to know if it is possible to download deb files for a 64 bit machine on a 32 bit machine.
I tried the unity interface on my netbook and I felt it is not as good as Gnome for a small screen. I want to know how ubuntu users can customize various Gnome desktop features to suite or to make best use of a netbook screen. For example I have deleted the bottom panel, and brought the top panel below, and have made it auto-hide. Also I have made the text size smaller everywhere.
I have also customised Firefox like so:
I have got rid of status bar, menu bar so on. I feel that the title bar on many applications is not so much useful. So can it be removed, as it is done in google chrome. In opera and chrome the tab bar is very thick, so I am looking for a way to reduce the size. Please post solutions to make optimal use of the netbook screen.
I want to setup openGL programming environment on ubuntu. What packages or tools I should install and what is the best way of getting into openGL as a newbie.
I want to shift from ubuntu-desktop 10.10 to ubuntu netbook edition 10.10 on my netbook. Currently, the moment I ssh into ubuntu from my ad-hoc network, ubuntu freezes. It always requires a cold shutdown. So hoping that netbook edition may not have this issue. I have custom installed many applications on the desktop edition. So I want save the app list into a script and run the script on the new installation, so that all apps will be downloaded and installed. I need suggestions as to the best way to achieve this.
Sometimes I boot into recovery kernel with CLI and networking for troubleshooting my laptop. So is there a way to connect to a wireless router or AP over command line? If it is possible what are the commands for the following:
- To list available networks.
- To connect to a network with: SSID, WPA2 key and DHCP mode.
- A command to connect with: SSID, ad-hoc mode, ip-address, netmask, gateway.
Is there a tool which can achieve high picture compression while preserving (as much as possible) the image quality and can compress images in batches, in order to make optimal images for websites?
I have two laptops: Dell xps M1210 and Dell vostro 1400. On MS windows the output volume is so loud that I just need to set volume to around 20% to listen music and watch videos. I use Bose TriPort In-Ear Headphones most of the times. On ubuntu, even if I set 100% volume on the multimedia player, on the desktop volume manager as well, and also on the ncurses GUI of alsa mixer, I get very low volume output. Sometimes while playing some vidoes the volume is so low that I barely hear any words. I have struggled for two years since I started to use ubuntu to solve this mystery. The same sound card which gives excellent sound on MS windows fails miserably on GNU/Linux. Few weeks back I bought an Asus 100PX EEE PC. To my surprise even it also has the same issue. I have tried many versions of ubuntu and also I have done manual compiles of alsa modules without any success. I have asked and read about it in every possible forums and howto's. Nothing has helped me to address the issue.
Is it possible to wake up Ubuntu from hibernation at a predefined time? It should not be WOL, but rather Ubuntu waking itself up. For example, it should do what the app WakeupOnStandBy does on MS Windows.
I had promissed my 120 students that I will install ubuntu 10.10 on their laptops but failed to do it.The laptops were dell vostro 4014. All have same hardware. I took one laptop and installed ubuntu and all the necessary packages, and also wine to run some windows software. I selected the default ext4 file system.
Then I tried to use clonezilla server to clone the installation. Clonezilla server shows boot menu splash screen, but later on it says that I might be having a latest NIC unsupported by the kernel. But the NIC of the laptop on which I had installed ubuntu works fine. Later I tried to use the clonezilla live cd to boot the laptop which has ubuntu. But when I press 'Y' to start cloning, it says 'something went wrong'. Again I tried the 'dd' command to save as disk image. But it copies empty space. So it is not feasible for me as it takes really long time.
I have made my students to wait for many days, daily they are coming and asking whether my setup is ready. Today I realized I can't do it. I have in a way convinced them not to go for windows. So they are waiting for me to have ubuntu installed on their laptops. Today evening some of them will come to collect the laptops I took from them to install ubuntu. Don't know how and what to tell them.