Applications

ssh setup

2018.02.13 [Ubuntu 16.04] - My minimal todo's after openssh-server installation. Note that below setup can cause some security implecations.

Client side

Client ssh public key needs registered to the server by doing something like:
% ssh USERNAME@SSH_SERVER_IP "echo `cat ~/.ssh/PUBKEY_FILENAME` >> ~/.ssh/authorized_keys"

. Also configure ssh as below for easier log-on:
~/.ssh/config
Host mysshserver
    HostName SERVER_HOSTNAME
    User USERNAME
    IdentityFile ~/.ssh/SECRET_KEY_FILENAME

, so ssh log-on can be done by doing:
% ssh mysshserver

. Alternatively, the key file can be specified on the commmand line:
% ssh USERNAME@SSH_SERVER_IP -i ~/.ssh/SECRECTKEY_FILENAME

Passshare

Private key can be protected by a passshare and if so it needs to be unlocked with every ssh logon with the key. Below command can handle it for you, although this is less secure.
% ssh-add ~/.ssh/id_rsa

Server side

Modify sshd config as below to 1) disable password authentication, 2) enable public key authentication, and optinoally, even 3) change port number for more security.
/etc/ssh/sshd_config
:
Port 22
:
#PasswordAuthentication yes
:
PubkeyAuthentication no
:
->




/etc/ssh/sshd_config
:
Port 8022 # or any allocatable number. Optional.
:
PasswordAuthentication no # note: uncommented
:
PubkeyAuthentication yes
:

Firefox Downgrade

2018.02.02 [Ubuntu 16.04] - Firefox (automatic) update to 58 disables useful add-ons like Scrapbook by Gomita. I've installed firefox 56 for the addon only with the following steps:
  1. Rename current ~/.mozilla folder to something like ~/.mozilla.back
  2. Download linux firefox 56 and extract it locally
  3. Start terminal and cd to the extracted folder, and run this command: 
    ./firefox
  4. When firefox starts, go to Prefernces -> "Firefox Updates" and check "Never check for updates (not recommended)". This is for firefox not to update self to newer version.
  5. Scrapbook now can be installed and used temporarily. When Scrapbook'ed is used, make sure the downloaded files are saved out of ~/.mozilla directory.
  6. To get back to the original env, quit the old firefox, then restore .mozilla folder.
Note: This works on my ubuntu 16.04 note PC as 56 was originally running on the same enviroment. Depending on the system any older verions of firefox may have compatibility issues.