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SSH SSH is “Secure SHell” Secure, compressed, widely supported, fast Allows both users to get jobs done, and also allows system administrators to sleep.

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Presentation on theme: "SSH SSH is “Secure SHell” Secure, compressed, widely supported, fast Allows both users to get jobs done, and also allows system administrators to sleep."— Presentation transcript:

1 SSH SSH is “Secure SHell” Secure, compressed, widely supported, fast Allows both users to get jobs done, and also allows system administrators to sleep at night Clients for every platform

2 What SSH can do Allows you to remotely log into systems and run commands Forward traffic over the SSH link (tunnel) Copy files Run commands without logging in

3 SSH basics

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6 Problems already 1.Always have to type my username in 2.Always have to type in full hostname 3.Always have to type in my password

7 Problems already Default behaviour – Tries to connect to remote server using the username of your current logged in user – This can be problematic, especially for Macs – Uses the domain name of your local machine (so can’t ssh ui from everywhere in world)

8 Problem solved You can override default behaviour by using a config file in your home directory – location is ~/.ssh/config

9 Problem solved 1.Username

10 Problem solved 1.Username Helps because Physics blocks/bans your IP address if you try connecting incorrectly more than 5 times common cause of this is wrong username

11 Problem solved 2. Full hostname

12 Problem solved 3. Password

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14 Problem solved 5. Create private/public key pair (ssh-keygen) Upload public key to remote server (ssh-copy-id) Unlock private key (ssh-add) SSH using keypair – Perfect for automated jobs and scripts! – Won’t work with lxplus – Make sure you password protect your SSH private key – Keep private key secure!

15 Other config options Wildcards and regex is allowed – e.g. Host * and Host *.ph.unimelb.edu.au will both work – Note that it reads the file from top down, and stops at the first entry that matches

16 Background of network in Physics ui.atlas.unimelb.edu.au -> Tier 3 log in node – restricted to hosts on AARNet network (uni’s) baker.ph.unimelb.edu.au -> School of Physics SSH gateway – accessible anywhere All other hosts – firewalled (inaccessible) – May think that this restricts you....

17 SSH forwarding When you ssh, it opens a persistent connection with SSH server We can use this connection to make other traffic travel “through” it – e.g. VNC, NX, SSH, web, files SSH will secure this traffic too! (basis for things like TOR and VPN)

18 SSH forwarding ssh –L localport:otherhost:otherhostport

19 SSH forwarding

20 Connections to local port 2222 get redirected over SSH to remote ssh server, which then redirects to port 22 on ui.atlas.unimelb.edu.au – perfect for SSH’ing “directly” to UI, or for copying files from “non-Uni” places

21 SSH forwarding

22 Original connection must be still open! (i.e. can’t close window or disconnect) Can do funky stuff, like be a “catch all” forwarder, for things like web (investigate the –D option in ssh and SOCKS proxy)

23 NX X is the graphical display manager in Linux It is bulky, and insecure over network Can forward this display using NX (NoMachine) Heavily compresses data, making it easier to display overseas/at home

24 NX For Melbourne, baker[1-6] have NX servers From home, port forward to port 22 on baker[1-6] through baker.ph.unimelb.edu.au Use NX client (http://www.nomachine.com/) to connect to forwarded porthttp://www.nomachine.com/

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