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Computing/LIP_Lisbon_Farm/2_How_To_Access

Contents

  1. Access
  2. Authentication: ssh + key
  3. Login

Access

  • The access ti LIP FARM it's done by ssh with public key to a remote machine based on RedHat: fermi.ncg.ingrid.pt

  • The fermi machine it's a cluster and it's composed by several machines: fermi01, fermi02, .... The access it's based on round-robin meaning for consecutive logins the users will be redirected to a different machine. 

host fermi.ncg.ingrid.pt
fermi.ncg.ingrid.pt has address 193.136.75.174
fermi.ncg.ingrid.pt has address 193.136.75.175
fermi.ncg.ingrid.pt has address 193.136.75.177
  • The fermi.ncg.ingrid.pt cluster it's reachable from inside LIP network and from lxplus.cern.ch machines.

  • For outside access users should always use the lnlip01/02 under lip.pt domain.

Authentication: ssh + key

  • The authentication for the LIP FARM it's done exclusively trough ssh with public key.
  • In order to generate a pair of private/public keys the user should run in there local machine the ssh-keygen command.

IMPORTANT : please choose a good password 

$ ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa): 
Created directory '/home/username/.ssh'.
Enter passphrase (empty for no passphrase):           
Enter same passphrase again:                          
Your identification has been saved in /home/username/.ssh/id_rsa.
Your public key has been saved in /home/username/.ssh/id_rsa.pub.
The key fingerprint is:
a8:60:b3:73:aa:ed:7f:bf:88:32:7a:fc:9d:00:1d:1d username@mydesktop
The key's randomart image is:
+--[ RSA 2048]----+
|      E          |
|     . .         |
|    . .          |
|   . . .         |
|  = . . S        |
| . = .           |
| .o +            |
| .=+ +.o         |
|o=+=+.+.o.       |
+-----------------+

  • By default the pair of keys generated by ssh-keygen command will be created in the ~/.ssh/ folder. Never share your private key (id_rsa)!!! 

cd 
ls -l ~/.ssh/
total 8
-rw------- 1 username group 1743 Feb 19 10:52 id_rsa
-rw-r--r-- 1 username group  404 Feb 19 10:52 id_rsa.pub

Login

ssh -A -l username fermi.ncg.ingrid.pt