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VerifyException: Failed To Verify - Intermittent error connecting to SFTP site

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in General by (220 points)

Hi there,

We have a number of servers that are constantly connecting to a 3rd Party Hosted SFTP site to check for files and potentially download files.  99.5% of the time there are no issues, but occasionally we're seeing errors like the one below.  The more servers we stand up we get the more we're seeing this.  

When using RSA we get this error:

ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :  Failed to connect - closing connection
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :  EnterpriseDT.Net.Ssh.Routrek.PKI.VerifyException: failed to verify
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at oYXcfQX7uKIveHVDw05.VjueRNXg0HVr4Jv2jXp.qM3MxIbBGcL(Byte[] , Byte[] )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.SnrM59mopjJ(SSH2DataReader , Byte[] , Byte[] )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.kpPM50qxduk(Byte[] , Byte[] , Byte[] )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.uG4M5RCSJOx(ssXiufOWDYGgEniWKJj )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.wdxM52D8vwj()
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at GFa5INQr93t8EZavibf.NxIBQlQibJwftVSFaRu.Connect(omtU1aZ1TwWSIBQTjL )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at xhd952cjWKWUPXYjDhI.HjosAwc4WIp71hfVHa5.wkmpasSrSb(W02ggUncxhSPIfOaYKt , ahmCjGlVU2iLavGqNS , JZQvVsdO9Hpvnrho0J , omtU1aZ1TwWSIBQTjL )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at xhd952cjWKWUPXYjDhI.HjosAwc4WIp71hfVHa5.C5Dp4DLdBI(W02ggUncxhSPIfOaYKt , ahmCjGlVU2iLavGqNS , Socket , ILogTag )
ERROR [SSHFTPClient] 16 May 2018 07:42:40.845 :     at EnterpriseDT.Net.Ftp.Ssh.SSHFTPClient.Connect()

When using DSA this one:

ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :  Failed to connect - closing connection
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :  EnterpriseDT.Net.Ssh.Routrek.PKI.VerifyException: DSA: failed to verify
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at tnS2Ycn3CvgWdD9fZ5i.eiRtcMnU8dJTA3rXL1v.Verify(Byte[] , Byte[] )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.di5M56TZrrI(SSH2DataReader , Byte[] , Byte[] )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.kpPM50qxduk(Byte[] , Byte[] , Byte[] )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.uG4M5RCSJOx(ssXiufOWDYGgEniWKJj )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at OZI2FuX9hIdrPNX6rfY.WVuqXXX1eBVxrj1cxFW.wdxM52D8vwj()
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at GFa5INQr93t8EZavibf.NxIBQlQibJwftVSFaRu.Connect(omtU1aZ1TwWSIBQTjL )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at xhd952cjWKWUPXYjDhI.HjosAwc4WIp71hfVHa5.wkmpasSrSb(W02ggUncxhSPIfOaYKt , ahmCjGlVU2iLavGqNS , JZQvVsdO9Hpvnrho0J , omtU1aZ1TwWSIBQTjL )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at xhd952cjWKWUPXYjDhI.HjosAwc4WIp71hfVHa5.C5Dp4DLdBI(W02ggUncxhSPIfOaYKt , ahmCjGlVU2iLavGqNS , Socket , ILogTag )
ERROR [SSHFTPClient] 25 Apr 2018 01:31:57.048 :     at EnterpriseDT.Net.Ftp.Ssh.SSHFTPClient.Connect()

We've already tried to troubleshoot this with the 3rd party SFTP provider, but they're not seeing anything strange on their end.

Does anyone have any ideas what could be happening here?

EDIT: We're using EDTFTPNet/Pro v9.0.0.20

Thanks!

Matt



















 
 

 





 




 





1 Answer











 
 





0 votes 























by 


(51.6k points)











This happens when you have server validation enabled, but you haven't configured the public keys for the hosts you're connecting to.  You can do this using the SecureFTPConnection.KnownHosts property.  You can find a how to on this topic here.
























by 


(220 points)














The RSA instance above has a known hosts file specified, the DSA does not.  If known hosts file not being specified were the issue wouldn't it break every time? We're seeing it work more than 99% of the time with these failures just happening intermittently.





















 









by 


(162k points)














I guess it is possible that occasionally the server sends back a corrupted public key?





















 

 
 

 





 

 



 






















 





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