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PuTTY session created for Telnet with a socks5 proxy (no auth needed) and named it to telnet_session_with_proxy

If I use PuTTY with selecting the given session, the Network Element is reachable (through the proxy), I can log in: putty.exe -load telnet_session_with_proxy 172.26.2.21

However, when PLINK is used (same session, same host), the proxy refuses the connection: plink.exe -load telnet_session_with_proxy 172.26.2.21 FATAL ERROR: Proxy error: Connection refused

What is the difference between PuTTY CLI and PLINK? There should not be any, should it? I suspect the session data is not fully or correctly read when executing plink.

If I hard-set the host address in the session and call plink with or without stating the host in the CLI (it is ignored), it connects to the host stated in the session through the proxy, e.g.: plink.exe -load telnet_session_with_proxy This is not a solution for me, as I want to set the host in the CLI using 1 session setup for several hosts.

Note that SSH sessions work OK through proxy with hosts defined in the CLI. It is not a solution for me either, as these old boxes only speak Telnet.

Can anyone help with this?

  • Plink
  • Telnet session
  • through proxy
  • host in CLI
Netcreator
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  • If it indeed works with SSH, but not with Telnet (and with PuTTY and not with Plink), then it looks like a bug, and you should report it to PuTTY, rather asking a question here. – Martin Prikryl Nov 15 '19 at 07:40
  • The PuTTY feedback page stresses to seek forum help before turning to them, as I am not 100% sure it is a bug. Thus, I am asking it here... – Netcreator Nov 16 '19 at 02:41

1 Answers1

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I used Wireshark to sniff what is actually happening, and it shows that the plink proxy connect is sent as it was SSH (port 22), in spite the session is set to telnet (23). Plink seems to ignore the port settings in the session when the host IP is empty. So, I believe it is bug and emailed it the PuTTY project, but I am not getting any reply.

The work-around: Set the "-P 23" (port 23, i.e. telnet) option explicitly in PLINK command.

Netcreator
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