Month: April 2015

vi & vim aids

Posted on by

For my quick reference.

To open two files in vi/vim and edit side by side (use CTRL-W + w to switch between the files):

# vim -O foo.txt bar.txt

To open a file and automatically move the cursor to a particular line number (for example line 80)

# vi +80 ~/.ssh/known_hosts

To display line numbers along the left side of a window, type one of the following command while using vi/vim:

:set number

or

:set nu

Here is how to cut-and-paste or copy-and-paste text using a visual selection in Vim.

Cut and paste:

  1. Position the cursor where you want to begin cutting.
  2. Press v to select characters (or uppercase V to select whole lines).
  3. Move the cursor to the end of what you want to cut.
  4. Press d to cut (or y to copy).
  5. Move to where you would like to paste.
  6. Press P to paste before the cursor, or p to paste after.

Copy and paste is performed with the same steps except for step 4 where you would press y instead of d:

  • d = delete = cut
  • y = yank = copy

 

 

Denyhosts Assists

Posted on by

Every so often a legitimate user will get blocked by deny hosts.  When this happens you can re-enable their access with these 8 simple steps (UPDATE: or use the faster version, see below):

  1. Stop DenyHosts 
    # service denyhosts stop
  2. Remove the IP address from /etc/hosts.deny
  3. Edit /var/lib/denyhosts/hosts and remove the lines containing the IP address.
  4. Edit /var/lib/denyhosts/hosts-restricted and remove the lines containing the IP address.
  5. Edit /var/lib/denyhosts/hosts-root and remove the lines containing the IP address.
  6. Edit /var/lib/denyhosts/hosts-valid and remove the lines containing the IP address.
  7. Edit /var/lib/denyhosts/users-hosts and remove the lines containing the IP address.
  8. Consider adding the IP address to /etc/hosts.allow 
    sshd:  IP_Address
  9. Start DenyHosts 
    # service denyhosts start

That’s it, your user should be able to access the server again.

The above process was a bit tedious however I am leaving it there because it gives details about what files are involved.  Since doing the above is time consuming here is what I have been doing that is much easier:

  1. Stop DenyHosts 
    # service denyhosts stop
  2. Remove the IP address from /etc/hosts.deny 
    1. # sed -i '/IP_ADDRESS/d' /etc/hosts.deny
  3. Remove all entries found under /var/lib/denyhosts/ containing the IP address. 
    1. # cd /var/lib/denyhosts
# for i in *hosts*;do sed -i '/IP_ADDRESS/d' "$i";done
  4. Consider adding the IP address to /etc/hosts.allow 
    sshd:  IP_Address
  5. Start DenyHosts 
    # service denyhosts start