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Why are FTP client logons to the zOS FTP server taking a very long time to get userid/password prompts or timing out?

Question & Answer


Question

Why are FTP client logons to the zOS FTP server taking a very long time to get userid/password prompts or timing out? This also occurs for FTP 127.0.0.1 using an ftp client on the same LPAR as the FTP server

Answer

FTPLOGGING TRUE is coded in the FTP server FTP.DATA file. By default this causes a DNS reverse name lookup to be attempted before generating log message EZYFS50I. A debug server trace shows that function getRemoteHost timeout out after reaching the DNS timeout value coded in the tcpip.data file being used by the FTP Daemon.

There are several solutions to this issue: 1) code FTPLOGGING TRUENODNS in the ftp data to allow no reverse DNS lookup to occur 2) lower the resolvertimeout value in the TCPIP.DATA file that the FTP Daemon is using 3) Correct the DNS to return hostnames for a reverse lookup

[{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SSSN3L","label":"z\/OS Communications Server"},"Platform":[{"code":"PF035","label":"z\/OS"}],"Component":"","Version":"","Line of Business":{"code":"LOB35","label":"Mainframe SW"}}]

Product Synonym

ZOSCS COMMSERVER

Document Information

Modified date:
22 March 2019

UID

dwa1498294

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