PING to AIX works but TELNET FTP SSH doesn't work

UNIX AIX
1 
root@PRD /> rsh DR
KFAFH_DR: protocol failure due to unexpected closure from server end

root@PRD /> telnet DR
Trying...
Connected to DR.
Escape character is '^]'.
Connection closed.

root@PRD /> ftp DR
Connected to KFAFH_DR.
421 Service not available, remote server has closed connection
ftp> bye

root@PRD /> ssh 10.10.10.42
ssh_exchange_identification: Connection closed by remote host

root@PRD /> telnet 10.10.10.42
Trying...
Connected to 10.10.10.42.
Escape character is '^]'.

#1 It was working: no services were taken down

#2 Suddenly couldn't connect

#3 After 1 hour, was able to telnet

How to identify the problem?

2

Hi,

Could you ping the server all the time that you couldn't connect an other way?

Is it a Physical or Virtual? What is the "uptime" on the server? Were problems experienced connecting to any other servers in the same location?

What if anything was in the logs?

Regards

Gull04

3

I would add:-

  • Possible router/firewall issues
  • Excessive server load (either CPU meaning it never fully connected or too much network traffic leaving it unable to respond)
  • DNS lookup failure, i.e. the DNS used by the server went off and the timeout was too long to allow the connection. The server will try to reverse lookup your connection for logging.
  • Client side issue perhaps?

It's all a bit vague so I can only be vague in suggestions.

Robin

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