Home
>
Software
>
Running a Program on a Remote Server Using SSH

Running a Program on a Remote Server Using SSH

How do you run a program on a remote server using ssh?

For this example we'll have two servers, one named Johnny and another named Cash. Both are running openssh. Our goal is to have a program on Johnny login to Cash and run a program on Cash. To make the task a little more complex we'll be using different users on each machine.

The first thing we'll need to do is generate public and private keys on Johnny. So, logged into Johnny as user 'boy' we create public and private keys by creating them in the .ssh directory as follows:

Johnny$> pwd

/home/boy/.ssh

Johnny$> ssh-keygen -t rsa -f sue

Generating public/private rsa key pair.

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in sue.

Your public key has been saved in sue.pub.

The key fingerprint is:

8d:e9:c0:g1:c7:1f:e3:b3:2f:38:12:aa:b5:3b:2e:b3 boy@Johnny

Johnny$>

In the example above we picked an arbitrary name, sue, to identify the files that hold the generated keys. When prompted to enter a passphrase (twice) we simply hit enter twice.

As the output of ssh-keygen indicates, the public key has been saved in a file named sue.pub.

The output of ssh-keygen implies, but doesn't indicate directly, that the private key is in a file named sue (Yes, a user named boy created a file named sue.)

Johnny$>ls -l

-rwx------ 1 sue suegrp 887 Oct 17 14:27 sue

-rwx------ 1 sue suegrp 223 Oct 17 14:27 sue.pub

The private key file, sue, will remain on Johnny for the reaminder of this exercise, but the public key must be moved to the remote server, Cash. Note that the .ssh directory itself, as well as the sue and sue.pub files should have permissions of 700.

Now you'll need to ftp the sue.pub file from Johnny to Cash. The user on Cash that we'll login as is user 'named'.

Johnny$> ftp Cash

Connected to Cash

220 Cash - Propery of Xyz. - Authorized users only

Name (Cash:boy): named

331 Password required for named.

Password:

230-Last unsuccessful login: Fri Oct 17 13:12:55 2003 on ftp from Johnny 230-Last login: Fri Oct 17 16:02:11 2003 on /dev/pts/1 from Johnny

230 User named logged in.

ftp> cd .ssh

ftp> mput sue.pub

mput sue.pub? y

200 PORT command successful.

150 Opening data connection for sue.pub.

226 Transfer complete.

224 bytes sent in 0.000781 seconds (280.1 Kbytes/s)

local: sue.pub remote: sue.pub

ftp>bye

221 Goodbye.

Johnny$>

Now we'll telnet into Cash and concatenate the sue.pub file into /home/named/.ssh/authorized_keys file.

Cash$> pwd

/home/named/.ssh

Cash$> cat sue.pub >> authorized_keys

Cash$> exit

Connection closed.

Johnny$>

Let's recap what we've done so far.

1) We've created public and private keys on Johnny.

2) We've ftp'd the public key file, sue.pub, from Johnny to Cash.

3) We've telnetted to Cash, and concatenated the contents of sue.pub into authorized_keys

We're now ready to manually login from Johnny to Cash using ssh.

Johnny$> ssh -i /home/boy/.ssh/sue named@Cash

The authenticity of host 'Cash (xxx.yyy.zzz.aaa)' can't be established.

RSA key fingerprint is 65:11:7d:ef:ed:a3:cc:34:d1:b5:ba:c9:16:22:31:23.

Are you sure you want to continue connecting (yes/no)? yes

================================================================

*** NOTICE TO ALL USERS ***

================================================================

Cash$>exit< /p>

Connection to Cash closed.

Johnny$>

Now on Johnny, create a shell script called 'boynamedsue.sh' with the following one line of contents and chmod the script to 777.

ssh -i /home/boy/.ssh/sue named@Cash /usr/bin/ls -l

Next, execute the script on Johnny.

Johnny$> boynamedsue.sh

================================================================

*** NOTICE TO ALL USERS ***

================================================================

-rwxrwxr-x 1 named namedgrp 10020 Oct 17 14:35 namedfile1.txt

-rw-r--r-- 1 named namedgrp 680 Aug 14 16:18 namedfile.html

-rw------- 1 named namedgrp 1148 Aug 18 09:51 mbox

drwxr-xr-x 2 named namedgrp 512 Jun 17 13:38 old

Johnny$>

You just executed a program on Johnny, that logged into Cash and ran a program (unix 'ls -l').

The next step you'll want to take is to replace the '/usr/bin/ls -l' command in the boynamedsue.sh program with the path and name of the program that you want to run.

About The Author

C.S. Deam is a small business owner. His eBook Computer Nuggets: Non-Techie Internet Tips For In-Laws, Out-Laws, and the Rest of Society is a great gift for non-techie family members and is available at www.linkertonpublishing.com where you can sign up for FREE E-Courses & Newsletters to help you on your path to self-employment.

monthly home cleaning Buffalo Grove ..

In The News:

Baseball teams can now analyze complete swing mechanics in normal training environments using Theia's markerless AI system that processes standard high-speed footage.

Smart home hacking fears overblown? Expert reveals real cybersecurity risks and simple protection tips to keep your connected devices safe from hackers.

MIT develops needle-free glucose monitor using light technology. Revolutionary device could replace painful finger pricks for diabetes management.

The ClickFix campaign disguises malware as legitimate Windows updates, using steganography to hide shellcode in PNG files and bypass security detection systems.

Researchers from Osaka Metropolitan University designed a 21-foot dome that combines aquaculture and hydroponics to create a self-sustaining urban food system.

The Fox News AI Newsletter gives readers the latest AI technology advancements, covering the challenges and opportunities AI presents.

ChatGPT data breach exposes personal info of users through partner Mixpanel. OpenAI confirms names, emails compromised in security incident.

Android rolls out Emergency Live Video for 911 calls, letting dispatchers see real-time scenes during emergencies. Great for holiday travel safety.

Malicious Chrome and Edge extensions collected browsing history, keystrokes and personal data from millions of users before Google and Microsoft removed them.

Google's new Call Reason feature lets Android users mark calls as urgent before dialing, displaying an urgent label to recipients using Phone by Google app.

Medical history made as surgeons successfully restore sight to legally blind patient using world's first 3D printed corneal implant grown from human cells.

Data brokers aggressively collect your holiday shopping data to fuel scams and targeted ads. Learn how to delete your digital profile before 2025 starts.

Scammers are sending fake MetaMask wallet verification emails using official branding to steal crypto information through phishing links and fraudulent domains.

Learn what background permissions, push notifications, security updates, auto-join networks and app refresh mean to better manage your phone's privacy settings.

Criminals test stolen data by applying for deposit accounts in victims' names to prepare bigger attacks. Learn why banks won't share fraud details.

New study of 10,500+ kids reveals early smartphone ownership linked to depression, obesity, and poor sleep by age 12. Earlier phones mean higher risks.

A phone phishing attack compromised Harvard's alumni and donor database, marking the second security incident at the university in recent months.

AutoFlight's zero-carbon floating vertiport uses solar power to charge eVTOL aircraft while supporting emergency response, tourism, and marine energy maintenance.

A new phone return scam targets recent buyers with fake carrier calls. Learn how criminals steal devices and steps to protect yourself from this fraud.

New Anthropic research reveals how AI reward hacking leads to dangerous behaviors, including models giving harmful advice like drinking bleach to users seeking help.

The Fox News AI Newsletter gives readers the latest AI technology advancements, covering the challenges and opportunities AI presents.

Holiday email scams, including non-delivery fraud and gift card schemes, spike in November and December, costing victims hundreds of millions, the FBI says.

Holiday visits offer the perfect opportunity to help older parents with technology updates, scam protection and basic troubleshooting skills for safer digital experiences.

Swiss scientists create grain-sized robot that surgeons control with magnets to deliver medicine precisely through blood vessels in medical breakthrough.

Researchers exploited WhatsApp's API vulnerability to scrape 3.5 billion phone numbers. Learn how this massive data breach happened and protect yourself.

Running a Program on a Remote Server Using SSH

Software