How can I verify port communications outside of telnet?

Products

• Workload Automation Agent
• CA Workload Automation AE
• CA Workload Automation AE - Business Agents (AutoSys)
• CA Workload Automation AE - Scheduler (AutoSys)
• CA Workload Automation AE - System Agent (AutoSys)
• CA Workload Automation DE
• CA Workload Automation DE - Business Agents (dSeries)
• CA Workload Automation DE - Scheduler (dSeries)
• CA Workload Automation DE - System Agent (dSeries)

Issue/Introduction

The telnet command is disabled by security policy. Is there another command based utility that we can use to test port communications?

Environment

Release : 12.0

Component : Workload Automation System Agent

Resolution

There are a number of ways that one can test network communications to validate port connectivity.

• Option 1 - (Linux only) Requires the nmap-ncat package to be installed. This can be done through yum install. (yum install nmap-ncat)
  Command syntax: nc -zv <host_name_or_ip> <port>
  
  Example of a successful connection:
  [root@machine tmp]# nc -zv machine.example.com 7523
  Ncat: Version 7.70 ( https://nmap.org/ncat )
  Ncat: Connected to <IP_MASKED>:7523.
  Ncat: 0 bytes sent, 0 bytes received in 0.01 seconds.
  
  Example of a failed connection:
  [root@machine 12.3]# nc -zv machine.example.com 7523
  Ncat: Version 7.70 ( https://nmap.org/ncat )
  Ncat: Connection refused.
  
  
• Option 2 - (Any OS) Requires the curl package to be installed. (On Linux, yum install curl)
  Command syntax: curl -v telnet://hostname:8443
  
  Example of a successful connection:
  [root@machine tmp]# curl -v telnet://machine.example.com:7523
  * Rebuilt URL to: telnet://machine.example.com:7523/
  *   Trying <IP_MASKED>...
  * TCP_NODELAY set
  * Connected to machine.mycompany.net (IP_MASKED) port 7523 (#0)
  
  Example of a failed connection:
  [root@machine 12.3]# curl -v telnet://machine.example.com:7523
  * Rebuilt URL to: telnet://machine.example.com:7523/
  *   Trying <IP_MASKED>..
  * TCP_NODELAY set
  * connect to <IP_MASKED> port 7523 failed: Connection refused
  * Failed to connect to machine.example.com port 7523: Connection refused
  * Closing connection 0
  curl: (7) Failed to connect to machine.example.com port 7523: Connection refused
  
  
  
• Option 3 - (Linux or UNIX only) Use cat /dev/tcp
  Command syntax: cat </dev/null >/dev/tcp/1.2.3.4/7163; echo $?
  This will return a value of either 0 or 1, with 0 being successful and 1 being failed.
  
  Example of successful connection:
  [root@machine tmp]# cat </dev/null >/dev/tcp/machine.example.com/7523; echo $?
  0
  Example of failed connection:
  [root@machine tmp]# cat </dev/null >/dev/tcp/machine.example.com/7523; echo $?
  1
  
  
• Option 4: (Windows only) Use Powershell.
  Command Syntax: Test-NetConnection -ComputerName machine.example.com -port 7523
  
  Example of successful connection:
  PS C:\Users\Administrator> Test-NetConnection -ComputerName machine.example.com -port 7523
  ComputerName     : machine.example.com
  RemoteAddress    : <IP_MASKED>
  RemotePort       : 7523
  InterfaceAlias   : tap7b3834e0-f5
  SourceAddress    : <IP_MASKED>
  TcpTestSucceeded : True
  
  Example of failed connection:
  PS C:\Users\Administrator> Test-NetConnection -ComputerName machine.example.com -port 7523
  

  WARNING: TCP connect to (<IP_MASKED> : 7523) failed

  
  ComputerName           : machine.example.com
  RemoteAddress          : <IP_MASKED>
  RemotePort             : 7523
  InterfaceAlias         : tap7b3834e0-f5
  SourceAddress          : <IP_MASKED>
  PingSucceeded          : True
  PingReplyDetails (RTT) : 1 ms
  TcpTestSucceeded       : False