3 PSK problems

PSK contains an odd number of hex-digits

Proxy or agent does not start, message in the proxy or agent log:

invalid PSK in file "/home/zabbix/zabbix_proxy.psk"

PSK identity string longer than 128 bytes is passed to GnuTLS

In TLS client side log:

gnutls_handshake() failed: -110 The TLS connection was non-properly terminated.

In TLS server side log.

gnutls_handshake() failed: -90 The SRP username supplied is illegal.

PSK longer than 32 bytes is passed to mbed TLS (PolarSSL)

In any Zabbix log:

ssl_set_psk(): SSL - Bad input parameters to function

Same PSK identity but different PSK values used by communicating components (example with OpenSSL)

In connecting-side log:

...[connect] TCP successful, cannot establish TLS to [[xx.xx.xx.xx]:xxx]: SSL_connect() returned SSL_ERROR_SSL: file s3_pkt.c line 1472: error:140943FC:SSL routines:ssl3_read_bytes:sslv3 alert bad record mac: SSL alert number 20: TLS read fatal alert "bad record mac"

In accepting-side log:

...failed to accept an incoming connection: from xx.xx.xx.xx: TLS handshake returned error code 1: file s3_pkt.c line 532: error:1408F119:SSL routines:SSL3_GET_RECORD:decryption failed or bad record mac: TLS write fatal alert "bad record mac"

Too long PSK value used with OpenSSL 1.1.1

In connecting-side log:

...OpenSSL library (version OpenSSL 1.1.1  11 Sep 2018) initialized
...
...In zbx_tls_connect(): psk_identity:"PSK 1"
...zbx_psk_client_cb() requested PSK identity "PSK 1"
...End of zbx_tls_connect():FAIL error:'SSL_connect() set result code to SSL_ERROR_SSL: file ssl\statem\extensions_clnt.c line 801: error:14212044:SSL routines:tls_construct_ctos_early_data:internal error: TLS write fatal alert "internal error"'

In accepting-side log:

...Message from 123.123.123.123 is missing header. Message ignored.

This problem typically arises when upgrading OpenSSL from 1.0.x or 1.1.0 to 1.1.1 and if the PSK value is longer than 512-bit (64-byte PSK, entered as 128 hexadecimal digits).

See also: Value size limits