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Use a pseudo-terminal over SSH to run a command on a remote machine.

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It is possible with SSH to run a command on a remote machine over SSH. The example below shows the output from the ps utility, which runs on a remote machine over SSH. After the command is run the connection is closed. This is a handy SSH tip.

┌──(john㉿DESKTOP-PF01IEE)-[~]
└─$ ssh -t jason@192.168.1.2 ps -eM
jason@192.168.1.2's password:
LABEL PID TTY TIME CMD
unconfined 1 ? 00:00:01 systemd
unconfined 2 ? 00:00:00 kthreadd
unconfined 3 ? 00:00:00 rcu_gp
unconfined 4 ? 00:00:00 rcu_par_gp
unconfined 6 ? 00:00:00 kworker/0:0H-kblockd
unconfined 9 ? 00:00:00 mm_percpu_wq
unconfined 10 ? 00:00:00 ksoftirqd/0
unconfined 11 ? 00:00:00 rcu_sched
unconfined 12 ? 00:00:00 migration/0
unconfined 13 ? 00:00:00 idle_inject/0
unconfined 14 ? 00:00:00 cpuhp/0
unconfined 15 ? 00:00:00 cpuhp/1
unconfined 16 ? 00:00:00 idle_inject/1
unconfined 17 ? 00:00:00 migration/1
unconfined 18 ? 00:00:00 ksoftirqd/1
unconfined 20 ? 00:00:00 kworker/1:0H-kblockd
unconfined 21 ? 00:00:00 cpuhp/2
unconfined 22 ? 00:00:00 idle_inject/2
unconfined 23 ? 00:00:00 migration/2
unconfined 24 ? 00:00:00 ksoftirqd/2
unconfined 26 ? 00:00:00 kworker/2:0H-kblockd
unconfined 27 ? 00:00:00 cpuhp/3
unconfined 28 ? 00:00:00 idle_inject/3
unconfined 29 ? 00:00:00 migration/3
unconfined 30 ? 00:00:00 ksoftirqd/3
unconfined 32 ? 00:00:00 kworker/3:0H-kblockd
unconfined 33 ? 00:00:00 kdevtmpfs
unconfined 34 ? 00:00:00 netns
unconfined 35 ? 00:00:00 rcu_tasks_kthre
unconfined 36 ? 00:00:00 kauditd
unconfined 37 ? 00:00:00 khungtaskd
unconfined 38 ? 00:00:00 oom_reaper
unconfined 39 ? 00:00:00 writeback
unconfined 40 ? 00:00:00 kcompactd0
unconfined 41 ? 00:00:00 ksmd
unconfined 42 ? 00:00:00 khugepaged
unconfined 89 ? 00:00:00 kintegrityd
unconfined 90 ? 00:00:00 kblockd
unconfined 91 ? 00:00:00 blkcg_punt_bio
unconfined 92 ? 00:00:00 tpm_dev_wq
unconfined 93 ? 00:00:00 ata_sff
unconfined 94 ? 00:00:00 md
unconfined 95 ? 00:00:00 edac-poller

You may also use this trick to back up a remote directory to a local machine over SSH.

┌──(john㉿DESKTOP-PF01IEE)-[~/Documents]
└─$ rsync -avz -e ssh jason@192.168.1.2:/home/jason/Documents/Boomsrc /home/john/Documents/Boomsrc
jason@192.168.1.2's password: 
receiving incremental file list
created directory /home/john/Documents/Boomsrc
Boomsrc/
Boomsrc/about.txt
Boomsrc/allegro.h
Boomsrc/am_map.c
Boomsrc/am_map.h
Boomsrc/bin2c.c
Boomsrc/bmp2c.c
Boomsrc/book.old
Boomsrc/boom.txt
Boomsrc/boomdeh.txt
Boomsrc/boomref.txt
Boomsrc/changes.old
Boomsrc/common.cfg
Boomsrc/copying
Boomsrc/d_deh.c
Boomsrc/d_deh.h
Boomsrc/d_englsh.h
Boomsrc/d_event.h
Boomsrc/d_french.h
Boomsrc/d_items.c
Boomsrc/d_items.h
Boomsrc/d_main.c
Boomsrc/d_main.h
Boomsrc/d_net.c
Boomsrc/d_net.h
Boomsrc/d_player.h
Boomsrc/d_textur.h
Boomsrc/d_think.h
Boomsrc/d_ticcmd.h
Boomsrc/dckboom.txt
Boomsrc/defswani.dat
Boomsrc/doom17.dat
Boomsrc/doom19.dat
Boomsrc/doomdata.h
Boomsrc/doomdef.c

It is also possible to use compression on an SSH connection to compress packets passing to and fro over a network connection.

┌──(john㉿DESKTOP-PF01IEE)-[~/Documents]
└─$ ssh -C -c aes256-ctr jason@192.168.1.2
jason@192.168.1.2's password: 
Welcome to Ubuntu 20.04.5 LTS (GNU/Linux 5.4.0-125-generic x86_64)
 
 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage
 
  System information as of Thu 22 Sep 2022 08:47:50 AEST
 
  System load:              0.0
  Usage of /:               11.1% of 915.82GB
  Memory usage:             2%
  Swap usage:               0%
  Temperature:              39.0 C
  Processes:                189
  Users logged in:          0
  IPv4 address for enp0s25: 192.168.1.2
  IPv6 address for enp0s25: fdc8:1451:5fa9:4700:d250:99ff:fe0d:ab0f
 
Save time starting to type a command or file name, then press tab to
complete Hit tab twice to bring up multiple completion options.
 
0 updates can be applied immediately.
 
New release '22.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.
 
Last login: Thu Sep 22 08:18:37 2022 from 192.168.1.5

If you try and use a cipher that is not supported on the server, it will print a listing of all available ciphers to choose from.

┌──(john㉿DESKTOP-PF01IEE)-[~/Documents]
└─$ ssh -C -c aes256-cbc jason@192.168.1.2
Unable to negotiate with 192.168.1.2 port 22: no matching cipher found. Their offer: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com

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