FKO_ERROR_INVALID_DATA_HMAC_COMPAREFAIL due to ECC key

[Dreamsorcerer]

I've setup 2 servers with fwknop. They are both running the same OS and are configured in much the same way.

Despite this, one of them I cannot connect to, and I get this error in the log each time I try to connect:

Jan 30 15:11:04 sam-backups fwknopd[26565]: (stanza #1) SPA Packet from IP: xxxx received with access source match
Jan 30 15:11:04 sam-backups fwknopd[26565]: [xxxx] (stanza #1) Error creating fko context (before decryption): Args contain invalid data: FKO_ERROR_INVALID_DATA_HMAC_COMPAREFAIL

The error suggests there is something wrong with the HMAC, but I have checked the HMAC configuration several times and tried generating a new HMAC, but I still get this error every time.

Server config looks like:

SOURCE              ANY
FW_ACCESS_TIMEOUT   3
GPG_REQUIRE_SIG     Y
GPG_DECRYPT_ID      [xxx]
GPG_ALLOW_NO_PW     Y
GPG_IGNORE_SIG_VERIFY_ERROR N
GPG_FINGERPRINT_ID  [xxx]
HMAC_DIGEST_TYPE    sha3_256
HMAC_KEY_BASE64     [xxx]
MAX_FW_TIMEOUT      60
OPEN_PORTS          tcp/22
REQUIRE_SOURCE_ADDRESS Y

Client config looks like:

[default]
ACCESS                      tcp/22
DIGEST_TYPE                 sha3_512
FW_TIMEOUT                  3
GPG_SIGNER                  [xxx]
HMAC_DIGEST_TYPE            sha3_256
RAND_PORT                   Y
USE_GPG                     Y
USE_GPG_AGENT               Y
USE_HMAC                    Y

[backup]
GPG_RECIPIENT               [xxx]
HMAC_KEY_BASE64             [xxx]
[sambull.org]
GPG_RECIPIENT               [xxx]
HMAC_KEY_BASE64             [xxx]

The HMAC was created with fwknopd --key-gen --hmac-key-len=128 and copied to the client config as well.

[Dreamsorcerer]

OK, this seems to happen when I use an ECC key on the server (but, an ECC key on the client is fine).

I'm not sure why this would not work, but the error message could certainly do with some improvements.