Is there a crypto policy or not?

[Tom Horsley]

The /etc/ssh/sshd_config file on my fedora 27 partition says:

# To opt out, uncomment a line with redefinition of  CRYPTO_POLICY=
# variable in  /etc/sysconfig/sshd  to overwrite the policy.
# For more information, see manual page for update-crypto-policies(8).

But there is no CRYPTO_POLICY environment variable setting
in /etc/sysconfig/sshd or in supposed system wide file
/etc/crypto-policies/back-ends/openssh-server.config I see
referenced in the sshd.service definition.

[Rex Dieter]

Tom Horsley wrote:
> The /etc/ssh/sshd_config file on my fedora 27 partition says:
>
> # To opt out, uncomment a line with redefinition of  CRYPTO_POLICY=
> # variable in  /etc/sysconfig/sshd  to overwrite the policy.
> # For more information, see manual page for update-crypto-policies(8).
>
> But there is no CRYPTO_POLICY environment variable setting
> in /etc/sysconfig/sshd

My /etc/sysconfig/sshd contains snippet:
...
# System-wide crypto policy:
# To opt-out, uncomment the following line
# CRYPTO_POLICY=

[Rick Stevens]

On 11/27/2017 12:42 PM, Tom Horsley wrote:
> The /etc/ssh/sshd_config file on my fedora 27 partition says:
>
> # To opt out, uncomment a line with redefinition of  CRYPTO_POLICY=
> # variable in  /etc/sysconfig/sshd  to overwrite the policy.
> # For more information, see manual page for update-crypto-policies(8).
>
> But there is no CRYPTO_POLICY environment variable setting
> in /etc/sysconfig/sshd or in supposed system wide file
> /etc/crypto-policies/back-ends/openssh-server.config I see
> referenced in the sshd.service definition.

It's sorta complex in that sshd is passed "-D $OPTIONS $CRYPTO_POLICY"
by systemd when it's started, so if you do:

CRYPTO_POLICY=

in /etc/sysconfig/sshd, then you disable the system-wide crypto policy
for sshd.

As far as the default crypto policy, it's in

/etc/crypto-policies/back-ends/openssh.config

which is (at least on my systems) a symlink to

/usr/share/crypto-policies/DEFAULT/openssh.txt

Hope that helps.
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