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FTPS: missing PBSZ 0 | Thales IoT Developer Community

June 28, 2018 - 11:02am, 2368 views

Hello,

when trying to transmit data via FTP with TLS, I have the following problem (EHS6, ELS61 Rel 2):

^SIS: 0,0,2100,"Ftp open(websrv7.linznet.at:990)"
^SIS: 0,0,2100,"SSL-Info: TLS, 3.3, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384"
^SIS: 0,0,2100,"SSL-Cert: C=US;O=Let's Encrypt;CN=Let's Encrypt Authority X3"
^SIS: 0,0,2100,"220 ProFTPD 1.3.5d Server (ProFTPD) [80.66.32.17]"
^SIS: 0,0,2100,"FTP Login OK"
^SIS: 0,0,2100,"S:503 You must issue the PBSZ command prior to PROT"
^SIS: 0,0,100,"FTP-ERR: 503 You must issue the PBSZ command prior to PROT"

I know, that FTP via TLS only supports implicit and PROT C.

But according to <https://tools.ietf.org/html/rfc4217#section-9> the PROT command MUST be preceded by a "PBSZ 0" command.

When I test FTPS connection with the test server <test.rebex.net/>, connection is possible. Maybe this server is more tolerant regarding the RFC.

Does anyone know a workaround?

-----ATI1-----

ELS61-E:
REVISION 02.000
A-REVISION 01.000.00
JRC-1.62.01.jad

EHS6:
REVISION 03.001
A-REVISION 00.000.51
JRC-1.56.54-CDG-00006.01.jad

Thanks and best regards

Klaus