Re: Serial port redirection

Corey Minyard
2003-12-03T13:02:30Z

Jeffrey Altman wrote:

> Its not a Kermit bug; If you pass the socket file descriptor to an
> external program
> the external program must understand telnet protocol. Otherwise, it
> can't send the
> correct data format.

No, it *is* a kermit bug. When kermit sends an 0xff character, it needs
to escape it per the standard telnet protocol. It's obviously not doing
this.

-Corey

>
>
>
>
> Peter Astrand wrote:
>
>>> Hi. I'm trying to find a generic serial port redirection solution for a
>>> Linux terminal server environment. I'd like a solution based on
>>> RFC2217. I'm particularly interested in syncing Palm Pilot PDAs.
>>
>> ...
>>
>>
>>> ser2net/sredird + Kermit
>>> ------------------------
>>> Kermit has built-in RFC2217 support, but it doesn't work for me:
>>>
>>> ---
>>> C-Kermit>set host localhost:4911
>>> DNS Lookup... Trying 127.0.0.1... Reverse DNS Lookup... (OK)
>>> localhost.localdomain connected on port 4911
>>> C-Kermit>set speed 2400
>>> localhost.localdomain:4911, 2400 bps
>>> C-Kermit>connect
>>> Connecting to host localhost.localdomain:4911
>>> Escape character: Ctrl-\ (ASCII 28, FS): enabled
>>> Type the escape character followed by C to get back,
>>> or followed by ? to see other options.
>>> ----------------------------------------------------
>>> ,
>>> Communications disconnect
>>> ---
>>>
>>
>>
>> Well, this was my fault: I didn't understand how Kermit worked. When
>> using "set carrier-watch off", things worked much better.
>> * BUT: When using Kermit as a RFC2217 client for transferring files with
>> ZMODEM, I get "Bad CRC" pretty much all the time. This happens *both*
>> with
>> the sredird, ser2net and Tactical Softwares Dialout/Server for Windows.
>> The problem seems to go away if I transfer files without "0xff"
>> bytes(!) This looks like a Kermit bug to me. I'll guess I have to
>> talk to the
>> Kermit folks about this.
>>
>>
>> * ser2net is totally incompatible with cyclades-serial-client. This is
>> because ser2net interprets RFC2217 a bit differently. sredird sends
>> command "101" as ack for command "1", while ser2net sends "1".
>> RFC2217 is
>> not very explicit about which way is most correct. The ser2net approach
>> looks better to me, but the sredird one is probably more widely used
>> (since Cyclades terminal server uses it, for example.) Probably, RFC2217
>> software needs to handle both cases.
>>
>>
>> Some more test cases:
>>
>> * minicom + cyclades-serial-client + sredird:
>> Works
>>
>> * pilot-link + cyclades-serial-client + sredird:
>> Does not work (see my previous mail)
>>
>> * pilot-link + cyclades-serial-client + Dialout/Server:
>> Works perfectly.
>> * photopc + cyclades-serial-client + sredird:
>> Does not work. I get "excessive retries".
>> * photopc + cyclades-serial-client + Dialout/Server:
>> Works perfectly.
>> So, the combination of sredird + cyclades-serial-client does not work
>> correctly.
>> Also, I tried running "Contract I.T. Communications Analyzer" on a
>> Windows
>> machine. One physical port was connected to a Linux machine via a null
>> modem cable. This machine ran sredird. One virtual port was created with
>> Tactical Softwares Dialout software, connecting to sredird.
>> Communications
>> Analyzer indicated 90% Byte Error Rate! Since cyclades-serial-client was
>> not involved in this test, I would say that it looks like sredird is
>> doing
>> something wrong.
>>
>>
>> If *anyone* has any ideas of how to solve these problem, please let me
>> know. I'm starting to run out of time and patience...
>>
>>
>> (Which mailing list is best for this topic?)
>>
>>
>>

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