Logging into Hydra

Access to the Hydra cluster is through a remote terminal connection.
If you are using a Mac you will use the built-in Terminal App, for Windows, use the program Putty, for Linux use ssh.
When you received your email from the Hydra admins with your user account information it will list your username and initial password. You will need these to login and change your password.
There are two computers (known as login nodes) that you can log into for Hydra access: hydra-login01.si.edu and hydra-login02.si.edu You can use either one.
You must use a "trusted" computer on the Smithsonian network or enable VPN to connect to Hydra.

Logging in

Open the Terminal application by going to /Applications/Utilities and finding Terminal.
1. You can get to the Utilities folder by going to the Go menu in the Finder and choosing Utilities
At the command prompt (ends with $) type in this command, replacing username with your hydra username from you welcome email:
```
$ ssh username@hydra-login01.si.edu
```
The first time you login you will see this message, type yes to continue:
```
The authenticity of host 'hydra-login01.si.edu' can't be established.
RSA key fingerprint is d8:8d:....
Are you sure you want to continue connecting (yes/no)? yes
```
You will get a password prompt where you should enter your initial password from your welcome email. Note: no text or bullets will appear when you type in your password.
```
Warning: Permanently added 'hydra-login01.si.edu' (RSA) to the list of known hosts.
Password: 
[username@login-3-1 ~]$ 
```
Note: login-3-1 is the name of hydra-login01.si.edu used internally by the server.
You are now logged into Hydra! Please continue to changing your password.

The preferred program to use on Windows to log into Hydra is the free program PuTTY. The program to download is putty.exe.
1. The downloaded putty.exe can be run without running a Windows installer program.
Start PuTTY and in the Configuration screen that opens enter hydra-login01.si.edu or hydra-login02.si.edu in the Host Name text box, then press Open

The first time you connect you will get a warning about the Server's host key, choose the "Yes" option
A terminal window will open. At the login as: prompt, enter your hydra username from your welcome email. Note: no text or bullets will appear when you type in your password.
```
login as: username
Using keyboard-interactive authentication.
Password:
[username@login-3-1 ~]$
```
Note: login-3-1 is the name of hydra-login01.si.edu used internally by the server.
You are now logged into Hydra! Please continue to changing your password.

From a trusted computer, use ssh to connect to one of the two login nodes;
otherwise (and only for SAO users), log onto login.cfa.harvard.edu and ssh from that host.

Linux (and Mac) users can enable password-less login into Hydra using the Public key authentication.

Follow the instructions here or Google "passwordless ssh mac" or "passwordless ssh mac" and follow the instructions.

Last updated 22 Sep 2015 MK/SGK.