5 ms·

SSH Cheat Sheet

80 points by marcobehler 4y ago

qwertox 4y ago
I also find `ssh-copy-id` useful.
peppermint_tea 4y ago
a few more examples on ssh tunnels : https://cloudbase.200013.net/doc/linux/ssh/ssh_tunelling.html https://cloudbase.200013.net/doc/linux/ssh/ssh_tunelling.htm...
- tommica 4y ago
  That is a useful guide - I used to do that with Spotify long time ago, when I was living in a different country
rollulus 4y ago
My favorite Konami code level of cheat: ssh escape sequences. On a new line: ~. to terminate a connection that’s stuck. Or ~? for more help.
- thedougd 4y ago
  Great one! This needs communicated more broadly. I spent too many years of my life killing terminals because of a dead ssh connection.
- danuker 4y ago
  Better yet, use Mosh. https://mosh.org/ https://mosh.org/
- LeoPanthera 4y ago
  Since it's sometimes unclear whether you are on a new line in a stuck terminal, I find it simpler to remember the sequence as [Return][~][.]
- marcobehler 4y ago
  Thanks, indeed a great one! Will put it in the article.
thedougd 4y ago
Favorites for scripting including the ability to run any command or script on the remote. ssh remotehost reboot Heredoc syntax also works: ssh remotehost <<'EOF' ls cat /etc/passwd reboot EOF
LeoPanthera 4y ago
> ssh-keygen -t rsa -b 4096 -C "your@email.com" Is there any evidence that 2048 bit RSA keys are insufficient? 4096 bit keys are absolutely huge. I don't know if working with them is also slower, but I would guess so.
dandanua 4y ago
The most annoying "feature" of ssh for me is the discrepancy between public keys presentations. How I suppose to verify fingerprint of a new server if it uses a different presentation in the keys file?
acatton 4y ago
PSA: scp is deprecated.[1] Please use sftp.[2] [1] https://lwn.net/Articles/835962/ https://lwn.net/Articles/835962/ [2] https://man.openbsd.org/sftp.1 https://man.openbsd.org/sftp.1
- marcobehler 4y ago
  Didn't know that! Thank you, will update the post.
- dhsysusbsjsi 4y ago
  As an scp user, this article was not a great advertisement for sftp. It listed a whole host of problems that don't apply to me, then finished with: "[sftp] disadvantage is a much less friendly user experience, especially in cases where one simply wants to type a command and see files move." I just want to copy a file. I'll keep using scp.
  - hotpotamus 4y ago
    I had that thought too, but rsync should mostly replace it. I have run into situations where rsync isn't available so scp -r has been helpful though.
- thefilmore 4y ago
  The scp command uses the SFTP protocol since OpenSSH 9.
- LanternLight83 4y ago
  IIRC, wasn't scp going to be rewritten in terms of SFTP behind the scenes?
- neurostimulant 4y ago
  scp uses sftp protocol by default since v8.8. You'll need to pass `-O` parameter to explicitly use the legacy scp protocol if you still need it for backward compatibility reason.
Daviey 4y ago
I like the idea for multiple Github accounts, but I have concerns over the suggestion: ``` Host github-work.com .. Host github-personal.com ``` Getting in the habit of using a fake FQDN (which right now aren't registered) feels pretty risky.
- cameronperot 4y ago
  This is a nifty trick, but I recently had an issue where it would offer my other keys even with IdentitiesOnly yes specified in ~/.ssh/config. I found a solution [1], but it's not the most elegant. [1] https://superuser.com/a/859719 https://superuser.com/a/859719
kaliszad 4y ago
I like how this guide also takes Windows into account, it has some unique challenges. I have written some notes especially on SSHFS (also for Windows!) and tunnels with SSH (e.g. SOCKS proxy) as an OrgPage: https://www.orgpad.com/s/wRIx3rNLZ6y https://www.orgpad.com/s/wRIx3rNLZ6y These tricks saved my bacon so many times already. Most of it can be used with the FUDO PAM jump host appliance (https://fudosecurity.com/fudo-pam/ https://fudosecurity.com/fudo-pam/) that is based on FreeBSD and one of the developers spoke about it and other things on https://www.bsdnow.tv/ https://www.bsdnow.tv/ I think. Some of it works with OpenWRT's Dropbear nicely as well.

80 points by marcobehler 4y ago

I also find `ssh-copy-id` useful.

a few more examples on ssh tunnels : https://cloudbase.200013.net/doc/linux/ssh/ssh_tunelling.html https://cloudbase.200013.net/doc/linux/ssh/ssh_tunelling.htm...

tommica 4y ago
That is a useful guide - I used to do that with Spotify long time ago, when I was living in a different country

rollulus 4y ago

My favorite Konami code level of cheat: ssh escape sequences. On a new line: ~. to terminate a connection that’s stuck. Or ~? for more help.

thedougd 4y ago
Great one! This needs communicated more broadly. I spent too many years of my life killing terminals because of a dead ssh connection.
danuker 4y ago
Better yet, use Mosh. https://mosh.org/ https://mosh.org/
LeoPanthera 4y ago
Since it's sometimes unclear whether you are on a new line in a stuck terminal, I find it simpler to remember the sequence as [Return][~][.]
marcobehler 4y ago
Thanks, indeed a great one! Will put it in the article.

thedougd 4y ago

Favorites for scripting including the ability to run any command or script on the remote. ssh remotehost reboot Heredoc syntax also works: ssh remotehost <<'EOF' ls cat /etc/passwd reboot EOF

LeoPanthera 4y ago

> ssh-keygen -t rsa -b 4096 -C "your@email.com" Is there any evidence that 2048 bit RSA keys are insufficient? 4096 bit keys are absolutely huge. I don't know if working with them is also slower, but I would guess so.

dandanua 4y ago

The most annoying "feature" of ssh for me is the discrepancy between public keys presentations. How I suppose to verify fingerprint of a new server if it uses a different presentation in the keys file?

acatton 4y ago

PSA: scp is deprecated.[1] Please use sftp.[2] [1] https://lwn.net/Articles/835962/ https://lwn.net/Articles/835962/ [2] https://man.openbsd.org/sftp.1 https://man.openbsd.org/sftp.1

marcobehler 4y ago
Didn't know that! Thank you, will update the post.
dhsysusbsjsi 4y ago
As an scp user, this article was not a great advertisement for sftp. It listed a whole host of problems that don't apply to me, then finished with: "[sftp] disadvantage is a much less friendly user experience, especially in cases where one simply wants to type a command and see files move." I just want to copy a file. I'll keep using scp.
- hotpotamus 4y ago
  I had that thought too, but rsync should mostly replace it. I have run into situations where rsync isn't available so scp -r has been helpful though.
thefilmore 4y ago
The scp command uses the SFTP protocol since OpenSSH 9.
LanternLight83 4y ago
IIRC, wasn't scp going to be rewritten in terms of SFTP behind the scenes?
neurostimulant 4y ago
scp uses sftp protocol by default since v8.8. You'll need to pass `-O` parameter to explicitly use the legacy scp protocol if you still need it for backward compatibility reason.

Daviey 4y ago

I like the idea for multiple Github accounts, but I have concerns over the suggestion: ``` Host github-work.com .. Host github-personal.com ``` Getting in the habit of using a fake FQDN (which right now aren't registered) feels pretty risky.

cameronperot 4y ago
This is a nifty trick, but I recently had an issue where it would offer my other keys even with IdentitiesOnly yes specified in ~/.ssh/config. I found a solution [1], but it's not the most elegant. [1] https://superuser.com/a/859719 https://superuser.com/a/859719

kaliszad 4y ago

I like how this guide also takes Windows into account, it has some unique challenges. I have written some notes especially on SSHFS (also for Windows!) and tunnels with SSH (e.g. SOCKS proxy) as an OrgPage: https://www.orgpad.com/s/wRIx3rNLZ6y https://www.orgpad.com/s/wRIx3rNLZ6y These tricks saved my bacon so many times already. Most of it can be used with the FUDO PAM jump host appliance (https://fudosecurity.com/fudo-pam/ https://fudosecurity.com/fudo-pam/) that is based on FreeBSD and one of the developers spoke about it and other things on https://www.bsdnow.tv/ https://www.bsdnow.tv/ I think. Some of it works with OpenWRT's Dropbear nicely as well.