Pinging directly will not work as it is behind the firewall.  We need to use curl pointing to the proxy to connect to cloudera.com at the OS level (could be any internet hostname) My previous responses tested using curl calling our proxy server at the OS level where NiFi is running and it is working. Only NiFi using Configuration service (Proxy server: HTTP) seems to broken with 2.7.2.  Before the upgrade from 1.26 to 2.7.2, NiFi worked connecting to cloudera using our own proxy server. ... View more

@MattWho  Server under 1.26.0 and 2.7.2 are behind the firewall. Both servers were in the same subnet.  After we upgraded one of the server from 1.26.0 to 2.6.0 then 2.7.2 having issue using the Proxy Configuration service (Proxy server) to reach the internet ie: cloudera.com. $ curl -x http://proxy.xxxx.ca:8080 sftp://cloudera.com:22 -v * Trying xxx.xx.xx.xxx:8080... * Connected to proxy.xxxx.ca (xxx.xx.xx.xxx) port 8080 (#0) * allocate connect buffer! * Establish HTTP proxy tunnel to cloudera.com:22 > CONNECT cloudera.com:22 HTTP/1.1 > Host: cloudera.com:22 > User-Agent: curl/7.76.1 > Proxy-Connection: Keep-Alive > < HTTP/1.1 403 Forbidden < Cache-Control: no-cache < X-XSS-Protection: 1 < Connection: Keep-Alive < Content-Type: text/html; charset=utf-8 < Content-Length: 729 < Pragma: no-cache < * Received HTTP code 403 from proxy after CONNECT * CONNECT phase completed! * Closing connection 0 curl: (56) Received HTTP code 403 from proxy after CONNECT Disregard the proxy 403 error as it cloudera.com is not listed in the proxy white list. The OS curl connection is working so it is not related to the host file (we cant use it behind the firewall).   In NiFi 1.26.0 works fine.  The server upgraded to 2.6.0/2.7.2 was 1.26.0 previously and didnt have this issue.  Seems to be a bug with 2.x.  If we use IP address in NiFi, the ListSFTP will work but not when using the hostname ie: cloudera.com; seems to be an issue passing the hostname to the proxy. DefaultConnectFuture[A@cloudera.com/<unresolved>:22]: Failed (UnknownHostException) to execute: cloudera.com Please advise. ... View more