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linux_ssh_access [2019/01/02 16:34]
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, from both inside ​and outside of the University.+All Linux servers run '​ssh'​.  Anyone with a CS account may log into these servers.  
 + 
 +From inside UVAyou 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 ===== 
 + 
 +**Use one of these options to access CS servers from outside of UVA.** 
 + 
 +==== Option 1: VPN access ==== 
 + 
 + 
 +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 ==== 
 + 
 +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 VPN. You cannot ssh directly into other department servers.//​ 
 + 
 +<​code>​ 
 +[ktm5j@outside-uva ~]$ ssh -l ktm5j portal.cs.virginia.edu 
 +ktm5j@portal.cs.virginia.edu'​s password:  
 +Last login: Mon Jul 29 14:12:10 2019 
 +ktm5j@portal04 ~ $ hostname 
 +portal04 ​                                              <​-- We are logged into portal cluster 
 +ktm5j@portal04 ~ $ ssh gpusrv01 ​                        <​-- We can now access gpusrv01 
 +ktm5j@gpusrv01'​s password: 
 +.... 
 +ktm5j@gpusrv01 ~ $ 
 +</​code>​ 
 + 
 +=== SSH Jumphost Options === 
 + 
 +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>​ 
 +     -J destination 
 +             ​Connect to the target host by first making a ssh connection to 
 +             the jump host described by destination and then establishing a 
 +             TCP forwarding to the ultimate destination from there. ​ Multiple 
 +             jump hops may be specified separated by comma characters. ​ This 
 +             is a shortcut to specify a ProxyJump configuration directive. 
 +             Note that configuration directives supplied on the command-line 
 +             ​generally apply to the destination host and not any specified 
 +             jump hosts. ​ Use ~/​.ssh/​config to specify configuration for jump 
 +             ​hosts. 
 +</​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 ''​%%gpusrv01%%''​ 
 + 
 +<​code>​ 
 +[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@gpusrv01'​s password: ​                                             <-- immediately able to log into gpusrv01 
 +.... 
 +ktm5j@gpusrv01 ~ $ 
 +</​code>​
  
 ===== Server Domain Names ===== ===== Server Domain Names =====
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 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 ==== 
 + 
 +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>​ 
 +username@power5:​~$ ping power3 
 +PING power3.cs.virginia.edu (128.143.67.43) 56(84) bytes of data. 
 +64 bytes from power3.cs.virginia.edu (128.143.67.43):​ icmp_seq=1 ttl=64 time=0.149 ms 
 +64 bytes from power3.cs.virginia.edu (128.143.67.43):​ icmp_seq=2 ttl=64 time=0.123 ms 
 +</​code>​ 
 + 
 +This will not work from outside of the CS network unless you modify your DNS search path to contain ​''​%%cs.virginia.edu%%''​.
  
 ===== Login ===== ===== Login =====
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 For information about SSH clients for Windows, see the article [[windows_ssh|SSH from Windows]] For information about SSH clients for Windows, see the article [[windows_ssh|SSH from Windows]]
 +
 +===== Servers =====
 +
 +For a listing of generally available servers in CS, see the article [[compute_resources|General Purpose Nodes]]
  
 ===== Login Restrictions (Info for Faculty) ===== ===== Login Restrictions (Info for Faculty) =====
  • linux_ssh_access.1546446844.txt.gz
  • Last modified: 2019/01/02 16:34
  • by ktm5j