8 ms·

Relevant: If your SSH server is public, you can give its address to https://sshcheck.com/ https://sshcheck.com/ and it will report any weak spots in your config

Relevant: If your SSH server is public, you can give its address to https://sshcheck.com/ https://sshcheck.com/ and it will report any weak spots in your config.

qersist3nce 5y ago
nice honeypot ;) (joking, thanks for the suggestion)
dspillett 5y ago
Useful. Though I'll have to hunt out (or try knock together) something that we can run locally for checking internal-only/white-listed hosts (like https://testssl.sh/ https://testssl.sh/ for HTTPS config checking).
crispyambulance 5y ago
Thanks, that's an interesting tool. But geezus, it's daunting to address SSH weaknesses unless you know ssh and it's configuration top to bottom. I don't! And I am not afraid to admit it. I just use ssh "as-is" on mainstream platforms, for example, whatever Amazon gives me on lightsail linux images or windows-10 or whatever's on my Mac and hope for the best. I mean, there's 4 different groups of algorithms to think about: "Key Exchange", "Server Host Key", "Encryption" and "MAC". Each with a bunch of choices, all different, all consisting of mouthfuls of impossible to remember complicated names. The sshcheck tool indicates that one of these is "insecure" because it may be "broken by nation states". What does that _really_ mean for a business or individual? ¯\_(ツ)_/¯ There are others which are labeled as "weak" so what does that mean? That it might someday be broken by nation-states? I think it's still useful, however. Why wouldn't you want to have the most secure ssh connections if it's just a matter of configuration? Ultimately, someone who uses the report from sshcheck has to decide whether it's worth it to google around, spend a solid 30 minutes or so, and figure out how to change their "out-of-the-box" ssh config to get a fully secure report from sshcheck.
- chasil 5y ago
  If you like Wireguard's security, you can emulate it in your sshd_config: Ciphers chacha20-poly1305@openssh.com KexAlgorithms curve25519-sha256@libssh.org MACs hmac-sha2-512-etm@openssh.com The MAC is irrelevant, as that function is built into the AEAD cipher, which are to be preferred (the alternate is AES-GCM). This will shut off a lot of legacy SSH clients. Android Connectbot specifically needs the AES cipher; adding it causes problems for putty. Otherwise, this is the classic "best practice" site for SSH: https://stribika.github.io/2015/01/04/secure-secure-shell.html https://stribika.github.io/2015/01/04/secure-secure-shell.ht...
  - egberts1 5y ago
    Exactly my finding too! Except certain version of MacOS (and Windows) ssh client would also be unable to connect.
    - chasil 5y ago
      I don't know about MacOS, but Microsoft's native OpenSSH supports this configuration. C:\>ssh -vv me@myDJBserver.myco.com OpenSSH_for_Windows_8.1p1, LibreSSL 3.0.2 ... debug2: KEX algorithms: curve25519-sha256@libssh.org ... debug2: ciphers ctos: chacha20-poly1305@openssh.com debug2: ciphers stoc: chacha20-poly1305@openssh.com ... debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none ... $ Above you can also see that the MAC is implicit with the chosen AEAD cipher.
    - password4321 5y ago
      You can brew install openssh on MacOS.
- gautamcgoel 5y ago
  Yo, do you play Supreme Commander? I think I saw someone with your username on FAF...
binkHN 5y ago
I tried out the tool, and all I got was a “Timeout exceeded while waiting for welcome message.” For every public SSH server I put up, I always configure a rate limiter in front of it to help thwart SSH attacks. Evidently, it thwarts this as well.
shapefrog 5y ago
I like it a lot ... I just dont know what to do about all my 'weak' results.
- akerl_ 5y ago
  Generally they’re going to be for legacy ciphers/MACs/etc. If you don’t need them, you can turn them off. If you’re the only one accessing your servers, you can honestly just pick a single option for each based on the highest security option that’s supported by all your client devices. https://infosec.mozilla.org/guidelines/openssh.html https://infosec.mozilla.org/guidelines/openssh.html is a good starting point. The lists of available options are sorted from left -> right, most optimal -> least.
  - shapefrog 5y ago
    Yeah I was kinda hoping that each of the fields would point to some instructions on disabling - but that is just me being too lazy to google things. edit: thanks for that link - swiped their kex, ciphers and macs and didnt break anything (that I know of)
wwarek 5y ago
I can recommend similar, but locally running tool, `ssh-audit`: https://github.com/jtesta/ssh-audit https://github.com/jtesta/ssh-audit Disclaimer: I'm not associated in any way
- password4321 5y ago
  Links to a publicly accessible https://www.ssh-audit.com https://www.ssh-audit.com

Relevant: If your SSH server is public, you can give its address to https://sshcheck.com/ https://sshcheck.com/ and it will report any weak spots in your config.

qersist3nce 5y ago

nice honeypot ;) (joking, thanks for the suggestion)

dspillett 5y ago

Useful. Though I'll have to hunt out (or try knock together) something that we can run locally for checking internal-only/white-listed hosts (like https://testssl.sh/ https://testssl.sh/ for HTTPS config checking).

crispyambulance 5y ago

Thanks, that's an interesting tool. But geezus, it's daunting to address SSH weaknesses unless you know ssh and it's configuration top to bottom. I don't! And I am not afraid to admit it. I just use ssh "as-is" on mainstream platforms, for example, whatever Amazon gives me on lightsail linux images or windows-10 or whatever's on my Mac and hope for the best. I mean, there's 4 different groups of algorithms to think about: "Key Exchange", "Server Host Key", "Encryption" and "MAC". Each with a bunch of choices, all different, all consisting of mouthfuls of impossible to remember complicated names. The sshcheck tool indicates that one of these is "insecure" because it may be "broken by nation states". What does that _really_ mean for a business or individual? ¯\_(ツ)_/¯ There are others which are labeled as "weak" so what does that mean? That it might someday be broken by nation-states? I think it's still useful, however. Why wouldn't you want to have the most secure ssh connections if it's just a matter of configuration? Ultimately, someone who uses the report from sshcheck has to decide whether it's worth it to google around, spend a solid 30 minutes or so, and figure out how to change their "out-of-the-box" ssh config to get a fully secure report from sshcheck.

chasil 5y ago
If you like Wireguard's security, you can emulate it in your sshd_config: Ciphers chacha20-poly1305@openssh.com KexAlgorithms curve25519-sha256@libssh.org MACs hmac-sha2-512-etm@openssh.com The MAC is irrelevant, as that function is built into the AEAD cipher, which are to be preferred (the alternate is AES-GCM). This will shut off a lot of legacy SSH clients. Android Connectbot specifically needs the AES cipher; adding it causes problems for putty. Otherwise, this is the classic "best practice" site for SSH: https://stribika.github.io/2015/01/04/secure-secure-shell.html https://stribika.github.io/2015/01/04/secure-secure-shell.ht...
- egberts1 5y ago
  Exactly my finding too! Except certain version of MacOS (and Windows) ssh client would also be unable to connect.
  - chasil 5y ago
    I don't know about MacOS, but Microsoft's native OpenSSH supports this configuration. C:\>ssh -vv me@myDJBserver.myco.com OpenSSH_for_Windows_8.1p1, LibreSSL 3.0.2 ... debug2: KEX algorithms: curve25519-sha256@libssh.org ... debug2: ciphers ctos: chacha20-poly1305@openssh.com debug2: ciphers stoc: chacha20-poly1305@openssh.com ... debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none ... $ Above you can also see that the MAC is implicit with the chosen AEAD cipher.
  - password4321 5y ago
    You can brew install openssh on MacOS.
gautamcgoel 5y ago
Yo, do you play Supreme Commander? I think I saw someone with your username on FAF...

binkHN 5y ago

I tried out the tool, and all I got was a “Timeout exceeded while waiting for welcome message.” For every public SSH server I put up, I always configure a rate limiter in front of it to help thwart SSH attacks. Evidently, it thwarts this as well.

shapefrog 5y ago

I like it a lot ... I just dont know what to do about all my 'weak' results.

akerl_ 5y ago
Generally they’re going to be for legacy ciphers/MACs/etc. If you don’t need them, you can turn them off. If you’re the only one accessing your servers, you can honestly just pick a single option for each based on the highest security option that’s supported by all your client devices. https://infosec.mozilla.org/guidelines/openssh.html https://infosec.mozilla.org/guidelines/openssh.html is a good starting point. The lists of available options are sorted from left -> right, most optimal -> least.
- shapefrog 5y ago
  Yeah I was kinda hoping that each of the fields would point to some instructions on disabling - but that is just me being too lazy to google things. edit: thanks for that link - swiped their kex, ciphers and macs and didnt break anything (that I know of)

wwarek 5y ago

I can recommend similar, but locally running tool, `ssh-audit`: https://github.com/jtesta/ssh-audit https://github.com/jtesta/ssh-audit Disclaimer: I'm not associated in any way

password4321 5y ago
Links to a publicly accessible https://www.ssh-audit.com https://www.ssh-audit.com