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linux_ssh_access [2019/07/29 19:19]
ktm5j
linux_ssh_access [2020/07/13 19:05] (current)
pgh5a [Option 2: Access via portal.cs.virginia.edu]
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 ====== Linux SSH Access ====== ====== Linux SSH Access ======
  
-All Linux servers ​in CS run an SSH server on port 22.  Anyone with a CS account may log into these servers.+All Linux servers run '​ssh'​.  Anyone with a CS account may log into these servers. ​
  
-**Update 07/29/19** We are now blocking SSH traffic for connections from outside of the UVA network This means that you are no longer ​able to SSH directly into CS hosts from outside of UVA.  However connections to ''​%%portal.cs.virginia.edu%%''​ are still allowed from outside of UVA.+From inside ​UVA, you can simply '​ssh'​ to CS servers typically by using a Terminal application like HyperTerm (Windows) or Terminal (Mac). 
 + 
 +From outside UVA, you are not able to '​ssh' ​directly into CS servers.  However connections to ''​%%portal.cs.virginia.edu%%''​ are still allowed from outside of UVA. 
 + 
 +You must use your CS domain userid (identical to your UVA userid) and password to '​ssh'​ to portal. For example: 
 + 
 +ssh -l jsp9ew portal.cs.virginia.edu. Alternatively,​ ssh jsp9ew@portal.cs.virginia.edu 
 + 
 +Note that if you are opening a terminal application on your Mac or PC, your username on the Mac or PC may be different from your CS domain userid. So be sure to include your CS domain userid on the '​ssh'​ command line. 
 + 
 +If you'd like to use a graphical windowing interface to department servers, see: [[nx_lab|NX Linux Remote Desktop Cluster]]
  
 ===== Access from Outside UVA ===== ===== Access from Outside UVA =====
 +
 +**Use one of these options to access CS servers from outside of UVA.**
  
 ==== Option 1: VPN access ==== ==== Option 1: VPN access ====
  
  
-If you are outside of the UVA network (off campus) then you can use the [[https://​virginia.service-now.com/​its?​id=itsweb_kb_article&​sys_id=f24e5cdfdb3acb804f32fb671d9619d0|UVA VPN]] to access CS servers via SSH.+If you are outside of the UVA network (off grounds) then you can use the [[https://​virginia.service-now.com/​its?​id=itsweb_kb_article&​sys_id=f24e5cdfdb3acb804f32fb671d9619d0|UVA VPN]] to access CS servers via SSH.
  
 ==== Option 2: Access via portal.cs.virginia.edu ==== ==== Option 2: Access via portal.cs.virginia.edu ====
  
-If you need to access CS servers from outside of UVA you can SSH directly into ''​%%portal.cs.virginia.edu%%''​ without having to use the VPN.  Once you are logged into the ''​%%portal%%''​ cluster, you can then access ​other CS servers ​via SSH. +You can ssh directly into ''​%%portal.cs.virginia.edu%%''​ without having to use the VPN.  Once you are logged into the ''​%%portal%%''​ cluster, you can then ssh to other CS servers. ​//Note! From off grounds, you can ONLY ssh into portal ​without using the VPNYou cannot ssh directly into other department servers.//
- +
-=== Example using portal.cs ===+
  
 <​code>​ <​code>​
-[ktm5j@outside-uva ~]$ ssh -l ktm5j power3.cs.virginia.edu 
- 
-^C                                                     <​-- Direct ssh access to power3 is denied 
 [ktm5j@outside-uva ~]$ ssh -l ktm5j portal.cs.virginia.edu [ktm5j@outside-uva ~]$ ssh -l ktm5j portal.cs.virginia.edu
 ktm5j@portal.cs.virginia.edu'​s password: ​ ktm5j@portal.cs.virginia.edu'​s password: ​
Line 27: Line 34:
 ktm5j@portal04 ~ $ hostname ktm5j@portal04 ~ $ hostname
 portal04 ​                                              <​-- We are logged into portal cluster portal04 ​                                              <​-- We are logged into portal cluster
-ktm5j@portal04 ~ $ ssh power3 ​                         ​<-- We can now access ​power3 +ktm5j@portal04 ~ $ ssh gpusrv01 ​                        <-- We can now access ​gpusrv01 
-ktm5j@power3's password:+ktm5j@gpusrv01's password:
 .... ....
-ktm5j@power3 ​~ $+ktm5j@gpusrv01 ​~ $
 </​code>​ </​code>​
  
 === SSH Jumphost Options === === SSH Jumphost Options ===
  
-The OpenSSH ssh client has an option ''​%%-J%%''​ to specify a host to use as a "​jumphost"​ that lets us access other servers ​inside of a firewalled network.  This combines two steps from the example above (ssh into portal.cs.virginia.edu and then ssh to power3) into one single command. ​ From the manpages:+The OpenSSH ssh client has an option ''​%%-J%%''​ to specify a host to use as a "​jumphost"​ that lets you access other servers ​directly, in one step.  This combines two steps (ssh into portal.cs.virginia.edu and then ssh to gpusrv01) into one single command. ​ From the manpages:
  
 <​code>​ <​code>​
Line 50: Line 57:
 </​code>​ </​code>​
  
-Here is how we use this option to "​jump"​ from portal.cs to another CS server. ​ Let's repeat the example of logging in to ''​%%power3%%''​+Here is how we use this option to "​jump"​ from portal.cs to another CS server. ​ Let's repeat the example of logging in to ''​%%gpusrv01%%''​
  
 <​code>​ <​code>​
-[ktm5j@outside-uva ~]$ ssh -l ktm5j power3 ​-J portal.cs.virginia.edu+[ktm5j@outside-uva ~]$ ssh -l ktm5j gpusrv01 ​-J portal.cs.virginia.edu
 ktm5j@portal04.cs.virginia.edu'​s password: ​                           <-- first asked to authenticate to portal ktm5j@portal04.cs.virginia.edu'​s password: ​                           <-- first asked to authenticate to portal
-ktm5j@power3's password: ​                                             <-- immediately able to log into power3+ktm5j@gpusrv01's password: ​                                             <-- immediately able to log into gpusrv01
 .... ....
-ktm5j@power3 ​~ $+ktm5j@gpusrv01 ​~ $
 </​code>​ </​code>​
- 
-This process can be made even easier with the use of password-less ssh keys.  When keys are set up properly you can log in (even using the -J jumphost options) without needing to type in a password. 
  
 ===== Server Domain Names ===== ===== Server Domain Names =====
  
 Computer Science hosts its own DNS server with authority over the ''​%%cs.virginia.edu%%''​ domain space. ​ Any server in CS will have a fully qualified domain name (fqdn) of ''​%%hostname.cs.virginia.edu%%''​. Computer Science hosts its own DNS server with authority over the ''​%%cs.virginia.edu%%''​ domain space. ​ Any server in CS will have a fully qualified domain name (fqdn) of ''​%%hostname.cs.virginia.edu%%''​.
- 
-If you want to log into a server named ''​%%gpusrv04%%'',​ then the domain address should be ''​%%gpusrv04.cs.virginia.edu%%''​. 
  
 ==== Short Names ==== ==== Short Names ====
  
-If you are inside of the Computer Science network then you can simply ​use the hostname of a server instead of its fully qualified name.  For example, if you are logged into a CS server, you can ping another server by its hostname alone.+If you are inside of the Computer Science network then use the hostname of a server instead of its fully qualified name.  For example, if you are logged into a CS server, you can ping another server by its hostname alone.
  
 <​code>​ <​code>​
  • linux_ssh_access.1564427970.txt.gz
  • Last modified: 2019/07/29 19:19
  • by ktm5j