Application
TCPSER turns a PC serial port into an emulated Hayes compatible modem that uses TCP/IP for incoming and outgoing connections. It can be used to allow older applications and systems designed for modem use to operate on the Internet. TCPSER supports all standard Hayes commands, and understands extended and vendor proprietary commands (though it does not implement many of them). TCPSER can be used for both inbound and outbound connections.
License
TCPSER is distributed under the GPL 2.0 or later
Installation
macOS
Install with Homebrew by
brew tap rickard-von-essen/formulae
brew install tcpser
Executable/Building
Simply clone the repository and use the appropriate make command to generate the executable. If unsure, try the default make command first.
| OS | Command |
|---|---|
| Default/Linux/macOS | make |
| Solaris | make -f Makefile.solaris |
| *BSD | gmake |
| Windows | make |
The application archive contains a pregenerated Windows 32 bit executable (tcpser.exe). No compilation should be required, though the GNU toolchain and the CYGWIN POSIX libraries can be used to regenerate the executable if desired:
Note that at least the cygwin1.dll library is required to operate tcpser under Windows. I recommend downloading a recent version from www.cygwin.com
Operation
tcpser -d <dev> -s <speed> -l <log_level> -t <tracing options> ...
-or-
tcpser -v <port> -s <speed> -l <log_level> -t <tracing options> ...
Examples
tcpser -d /dev/ttyS0 -s 38400 -l 7 -tsSiI -i "s0=1" -p 6400
Will start tcpser on ttyS0 at 38400 bps, level 7 logging, tracing of inbound serial, outbound serial, inbound IP, outbound IP, init modem to answer after 1 ring, and listen for incoming connections on port 6400
tcpser -v 25232 -s 38400 -l 4 -p 23
Will set up an ip232 port at 25232, report 38400 bps connections, level 4 logging, and listen for incoming connections on port 23.
tcpser -h will provide additional information
tcpser can be configured to send the contents of a file upon:
| Event | Flags |
|---|---|
| connect | -c -C |
| answer | -a -A |
| no-answer | -I |
| busy | -B |
| inactivity-timeout | -T |
For connect and answer, there are separate options for sending a file to the local serial connection (-c, -a) and the remote IP connection (-C, -A).
If tcpser connects to a telnet service, it will negotiate the connection using the telnet protocol. If telnet is detected, then tcpser will support RFC 856 (Telnet Binary Transmission), so that 8-bit file transfers will work correctly.
tcpser can be configured to support multiple serial/ip232 ports on one TCP/IP port. Simply repeat the -s and -d/-v parameters on the command line for each serial/ip232 port to be configured. Options s,S,a,A,c,C,I, and T will "propagate" to subsequent connections, unless they are redefined. Defaults for s and S are 38400. This configuration enables the operation of a multi-line BBS on one TCP/IP port.
Frequently used addresses can be configured in the "phonebook", like so:
tcpser .... -nhome=jbrain.com:6400
This is also useful for systems that do not accept non-numeric phone numbers:
tcpser .... -n9169651701=bbs.fozztexx.com
One can even "hide" a regular IP address or DNS entry by aliasing it to something else:
tcpser .... -njbrain.com=bestbbs.com
At this point, phonebook support is very alpha, so use with care.
Emulation
All of the standard Hayes commands should behave as expected. Some of of the proprietary commands are not implemented, but should not cause errors.
Examples:
| Command | Effect |
|---|---|
| ats0=1 | set number of rings to answer |
| ata | answer the line |
| ath0 | hang up |
| ats12? | query S register 12 |
| ate0 | turn off echo |
| at&k3 | set flow control to RTS/CTS |
| atdtjbrain.com:6400 | "dial" jbrain.com, port 6400 (defaults to port 23) |
| atdl | "dial" last number |
| a/ | repeat last command |
Commands can be chained, as on a regular modem:
ats0=1z&c1&k3%f0s3=13dtjbrain.com
tcpser supports the Hayes break sequence semantics, so +++ should operate correctly, even if the sequence of characters is used in normal data transmissions.i
Cable
tcpser can be used with a regular null modem cable, but it utilizes the DTR line on the PC serial port to reflect the state of the DCD line as seen by the target system. On a normal null-modem cable, DTR is mapped to DCD/DSR, which implies DSR will also reflect the state of DCD on the target machine. However, some systems (notably those utilizing the 6551 ACIA communication IC) will not transmit unless DSR is held high. In this case, a quick qorkaround is to force DCD to be held high by adding -i"&c0" to the tcpser parameter list. However, this also prevents normal operation of the DCD line, which is needed by some BBS systems. A more permanent solution is to construct a modified null-modem cable or modify an existing cable to the following specifications:
PC Target
CTS-----RTS
RTS-----CTS
SND-----RCV
RCV-----SND
DTR-----DCD
DCD-+-+-DTR
| |
DSR-+ +-DSR
GND-----GND
This differs from a regular null-modem cable in that the target machine has DSR looped to DTR, not to DCD. Note that this cable is directional.
Normally, the target machine will configure DSR to float to a high state if unconnected. As well, PCs do not require a valid DSR line for operation. Thus, a simpler cable can be constructed that is bi-directional:
CTS-----RTS
RTS-----CTS
SND-----RCV
RCV-----SND
DTR-----DCD
DCD-----DTR
GND-----GND
Unless there are issues, we recommend this simplified version, as it can be installed in either direction.
As an even simpler solution, many have simply taken a normal rs232 DE-9F to DE-9M cable and removed pin 6 from the male end (DSR). This is fine, but the cable must be installed between the null modem adapter and the target machine:
PC ----- null-modem adapter ----- cable with pin 6 removed ------ target machine
Any other configuration will not work correctly.
Platform notes
Win32 users should use /dev/ttyS0-3 for COM1-4. At present, using "com1:" does not operate correctly.
Raymond Day sends the following Ubuntu 7.10 autorun scripts:
In:
/etc/init.d/
Make a file named something like tcpser with this code in it:
#!/bin/sh
# Start tcpser at 1200 boud on both RS232 ports for Q-Link Reloaded.
case "$1" in
'start')
tcpser -d /dev/ttyS0 -s 1200 -i"e0&k0&c0" -n"5551212"=66.135.39.36:5190&
tcpser -d /dev/ttyS1 -p 6401 -s 1200 -i"e0&k0&c0" -n"5551212"=66.135.39.36:5190&
;;
'stop')
;;
*)
echo "Usage: $0 { start | stop }"
;;
esac
exit 0
Help
tcpser has a small but active user community. Help can be found by asking a question in comp.sys.cbm, on the NEWNet #c64friends IRC channel, or by emailing the author.
Jim Brain tcpser@jbrain.com www.jbrain.com
Thanks:
- The ip232 support was added by Anthony Tolle.
- Telnet support fixes were added by Gene Buckle (geneb): https://github.com/geneb/tcpser
- Automatic modem parity detection and numerous fixes were added by Chris Osborn (fozztexx): https://github.com/FozzTexx/tcpser