Alternate methods to verify network communications other than telnet

Products

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

Issue/Introduction

Most companies disable telnet due to security policy. This article provides alternate methods to perform and capture network communications tests.

Environment

Any

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   : xxxxxxxxxxxxx
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         : xxxxxxxxxxxxx
SourceAddress          : <IP_MASKED>
PingSucceeded          : True
PingReplyDetails (RTT) : 1 ms
TcpTestSucceeded       : False