C-Kermit Configuration Options

Frank da Cruz
The Kermit Project
Columbia University

As of: C-Kermit 8.0.211, 10 April 2004
This page last updated: Sun Apr 11 16:45:55 2004 (New York USA Time)

IF YOU ARE READING A PLAIN-TEXT version of this document, note that this file is a plain-text dump of a Web page. You can visit the original (and possibly more up-to-date) Web page here:

  http://www.columbia.edu/kermit/ckccfg.html

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CONTENTS

  1. FILE TRANSFER
  2. SERIAL COMMUNICATION SPEEDS
  3. FULLSCREEN FILE TRANSFER DISPLAY
  4. CHARACTER SETS
  5. APC EXECUTION
  6. PROGRAM SIZE
  7. MODEM DIALING
  8. NETWORK SUPPORT
  9. EXCEPTION HANDLING
 10. SECURITY FEATURES
 11. ENABLING SELECT()
 12. I/O REDIRECTION
 13. FLOATING-POINT NUMBERS, TIMERS, AND ARITHMETIC
 14. SPECIAL CONFIGURATIONS
  I. SUMMARY OF COMPILE-TIME OPTIONS

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OVERVIEW

For details about your particular operating system, also see the system-specific installation instructions file, such as the C-Kermit Installation Instructions for Unix.

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1. FILE TRANSFER

Prior to version 7.0, C-Kermit was always built with the most conservative Kermit file-transfer protocol defaults on every platform: no control-character prefixing, 94-byte packets, and a window size of 1.

Starting in version 7.0, fast settings are the default. To override these at compile time, include:

  -DNOFAST

in the C compiler CFLAGS. Even with the fast defaults, C-Kermit automatically drops down to whatever window and packet sizes requested by the other Kermit, if these are smaller, when sending files (except for control-character unprefixing, which is not negotiated, and which is now set to CAUTIOUS rather than NONE at startup). C-Kermit's settings prevail when it is receiving.

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2. SERIAL COMMUNICATION SPEEDS

As of 6 September 1997, a new simplified mechanism for obtaining the list of legal serial interface speeds is in place:

• If the symbol TTSPDLIST is defined, the system-dependent routine ttspdlist() is called at program initialization to obtain the list.

• This symbol should be defined only for C-Kermit implementations that have implemented the ttspdlist() function, typically in the ck?tio.c module. See ckutio.c for an example.

• TTSPDLIST is automatically defined in ckcdeb.h for UNIX. Add the appropriate #ifdefs for other platforms when the corresponding ttspdlist() functions are filled in.

• If TTSPDLIST is (or normally would be) defined, the old code (described below) can still be selected by defining NOTTSPDLIST.

The ttspdlist() function can obtain the speeds in any way that works. For example, based simply on #ifdef Bnnnn..#endif (in UNIX). Although it might be better to actually check each speed against the currently selected hardware interface before allowing it in the array, there is usually no passive and/or reliable and safe way to do this, and so it's better to let some speeds into the array that might not work, than it is to erroneously exclude others. Speeds that don't work are caught when the SET SPEED command is actually given.

Note that this scheme does not necessarily rule out split speed operation, but effectively it does in C-Kermit as presently constituted since there are no commands to set input and output speed separately (except the special case "set speed 75/1200").

Note that some platforms, notably AIX 4.2 and 4.3, implement high serial speeds transparently to the application, e.g. by mapping 50 bps to 57600 bps, and so on.

That's the whole deal. When TTSPDLIST is not defined, the following applies:

Speeds are defined in two places: the SET SPEED keyword list in the command parser (as of this writing, in the ckuus3.c source file), and in the system- dependent communications i/o module, ck?tio.c, functions ttsspd() (set speed) and ttgspd() (get speed). The following speeds are assumed to be available in all versions:

  0, 110, 300, 600, 1200, 2400, 4800, 9600

If one or more of these speeds is not supported by your system, you'll need to change the source code (this has never happened so far). Other speeds that are not common to all systems have Kermit-specific symbols:

               Symbol       Symbol
  Speed (bps)  to enable    to disable
       50       BPS_50       NOB_50
       75       BPS_75       NOB_75
       75/1200  BPS_7512     NOB_7512
      134.5     BPS_134      NOB_134
      150       BPS_150      NOB_150
      200       BPS_200      NOB_200
     1800       BPS_1800     NOB_1800
     3600       BPS_3600     NOB_3600
     7200       BPS_7200     NOB_7200
    14400       BPS_14K      NOB_14K
    19200       BPS_19K      NOB_19K
    28800       BPS_28K      NOB_28K
    38400       BPS_38K      NOB_38K
    57600       BPS_57K      NOB_57K
    76800       BPS_76K      NOB_76K
   115200       BPS_115K     NOB_155K
   230400       BPS_230K     NOB_230K
   460800       BPS_460K     NOB_460K
   921600       BPS_921K     NOB_921K

The ckcdeb.h header file contains default speed configurations for the many systems that C-Kermit supports. You can override these defaults by (a) editing ckcdeb.h, or (b) defining the appropriate enabling and/or disabling symbols on the CC command line, for example:

  -DBPS_14400 -DNOB_115200

or the "make" command line, e.g.:

  make blah "KFLAGS=-DBPS_14400 -DNOB_115200"

Note: some speeds have no symbols defined for them, because they have never been needed: 12.5bps, 45.5bps, 20000bps, etc. These can easily be added if required (but they will work only if the OS supports them).

IMPORTANT: Adding one of these flags at compile time does not necessarily mean that you will be able to use that speed. A particular speed is usable only if your underlying operating system supports it. In particular, it needs to be defined in the appropriate system header file (e.g. in UNIX, cd to /usr/include and grep for B9600 in *.h and sys/*.h to find the header file that contains the definitions for the supported speeds), and supported by the serial device driver, and of course by the physical device itself.

ALSO IMPORTANT: The list of available speeds is independent of how they are set. The many UNIXes, for example, offer a wide variety of APIs that are BSD-based, SYSV-based, POSIX-based, and purely made up. See the ttsspd(), ttgspd(), and ttspdlist() routines in ckutio.c for illustrations.

The latest entries in this horserace are the tcgetspeed() and ttsetspeed() routines found in UnixWare 7. Unlike other methods, they accept the entire range of integers (longs really) as speed values, rather than certain codes, and return an error if the number is not, in fact, a legal speed for the device/driver in question. In this case, there is no way to build a list of legal speeds at compile time, since no Bnnnn symbols are defined (except for "depracated, legacy" interfaces like ioctl()) and so the legal speed list must be enumerated in the code -- see ttspdlist() in ckutio.c.

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3. FULLSCREEN FILE TRANSFER DISPLAY

New to edit 180 is support for an MS-DOS-Kermit-like local-mode full screen file transfer display, accomplished using the curses library, or something equivalent (for example, the Screen Manager on DEC VMS). To enable this feature, include the following in your CFLAGS:

  -DCK_CURSES

and then change your build procedure (if necessary) to include the necessary libraries. For example, in Unix these are usually "curses" or "ncurses" (and more recenlty, "ncursesw" and "slang"), perhaps also "termcap", "termlib", or "tinfo":

  "LIBS= -lcurses -ltermcap"
  "LIBS= -lcurses -ltermlib"
  "LIBS= -lncurses"
  "LIBS= -ltermlib"
  "LIBS= -ltinfo"

"man curses" for further information, and search through the Unix makefile for "CK_CURSES" to see many examples, and also see the relevant sections of the Unix C-Kermit Installation Instructions, particularly Sections 4 and 9.2.

There might still be a complication. Some implementations of curses reserve the right to alter the buffering on the output file without restoring it afterwards, which can leave Kermit's command processing in a mess when the prompt comes back after a fullscreen file transfer display. The typical symptom is that characters you type at the prompt after a local-mode file transfer (i.e. after seeing the curses file-transfer display) do not echo until you press the Return (Enter) key. If this happens to you, try adding

  -DCK_NEWTERM

to your makefile target (see comments in screenc() in ckuusx.c for an explanation).

If that doesn't fix the problem, then use a bigger hammer and replace -DCK_NEWTERM with:

  -DNONOSETBUF

which tells Kermit to force stdout to be unbuffered so CBREAK mode can work.

In SCO Xenix and SCO UNIX, there are two separate curses libraries, one based on termcap and the other based on terminfo. The default library, usually terminfo, is established when the development system is installed. To manually select terminfo (at compile time):

  compile -DM_TERMINFO and link -ltinfo

and to manually select termcap:

  compile -DM_TERMCAP and link -ltcap -ltermlib

<curses.h> looks at M_TERMINFO and M_TERMCAP to decide which header files to use. /usr/lib/libcurses.a is a link to either libtinfo.a or libtcap.a. The C-Kermit compilation options must agree with the version of the curses library that is actually installed.

NOTE: If you are doing an ANSI-C compilation and you get compile time warnings like the following:

  Warning: function not declared in ckuusx.c: wmove, printw, wclrtoeol,
  wclear, wrefresh, endwin, etc...

it means that your <curses.h> file does not contain prototypes for these functions. The warnings should be harmless.

New to edit 190 is the ability to refresh a messed-up full-screen display, e.g. after receiving a broadcast message. This depends on the curses package including the wrefresh() and clearok() functions and the curscr variable. If your version has these, or has code to simulate them, then add:

  -DCK_WREFRESH

The curses and termcap libraries add considerable size to the program image (e.g. about 20K on a SUN-4, 40K on a 386). On some small systems, such as the AT&T 6300 PLUS, curses can push Kermit over the edge... even though it compiles, loads, and runs correctly, its increased size apparently makes it swap constantly, slowing it down to a crawl, even when the curses display is not in use. Some new makefile targets have been added to take care of this (e.g. sys3upcshcc), but similar tricks might be necessary in other cases too.

On the curses file-transfer display, just below the "thermometer", is a running display of the transfer rate, as a flat quotient of file characters per elapsed seconds so far. You can change this to an average that gives greater weight to recent history (0.25 * instantaneous cps + 0.75 * historical cps) by adding -DCPS_WEIGHTED to your CFLAGS (sorry folks, this one is not worth a SET command). You can choose a second type of weighted average in which the weighting smooths out progressively as the transfer progresses by adding -DCPS_VINCE to -DCPS_WEIGHTED.

An alternative to curses is also available at compile time, but should be selected if your version of Kermit is to be run in local mode only in an ANSI terminal environment, for example on a desktop workstation that has an ANSI console driver. To select this option in place of curses, define the symbol MYCURSES:

  -DMYCURSES

instead of CK_CURSES. The MYCURSES option uses built-in ANSI (VT100) escape sequences, and depends upon your terminal or console driver to interpret them correctly.

In some C-Kermit builds, we replace printf() via #define printf... However, this can cause conflicts with the [n]curses header files. Various hacks are required to get around this -- see ckutio.c, ckufio.c, ckuusx.c, ckucmd.c, etc.

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4. CHARACTER SETS

Since version 5A, C-Kermit has included support for conversion of character sets for Western European languages (i.e. languages that originated in Western Europe, but are now also spoken in the Western Hemisphere and other parts of the world), via ISO 8859-1 Latin Alphabet 1, for Eastern European languages (ISO Latin-2), Hebrew (and Yiddish), Greek, and Cyrillic-alphabet languages (ISO Latin/Cyrillic). Many file (local) character sets are supported: ISO 646 7-bit national sets, IBM code pages, Apple, DEC, DG, NeXT, etc.

To build Kermit with no character-set translation at all, include -DNOCSETS in the CFLAGS. To build with no Latin-2, add -DNOLATIN2. To build with no Cyrillic, add -DNOCYRIL. To omit Hebrew, add -DNOHEBREW. If -DNOCSETS is *not* included, you'll always get LATIN1. To build with no KANJI include -DNOKANJI. There is presently no way to include Latin-2, Cyrillic, Hebrew, or Kanji without also including Latin-1.

Unicode support was added in C-Kermit 7.0, and it adds a fair amount of tables and code (and this is only a "Level 1" implementation -- a higher level would also require building in the entire Unicode database). On a PC with RH 5.2 Linux, building C-Kermit 7.0, we get the following sizes:

  NOCSETS NOUNICODE NOKANJI   Before    After                  
   [   ]    [   ]    [   ]    1329014   (Full)
   [   ]    [   ]    [ X ]    1325686   (Unicode but no Kanji)
   [   ]    [ X ]    [   ]    1158837   (All charsets except Unicode)
   [ X ]    [ x ]    [ x ]    1090845   (NOCSETS implies the other two)

Note, by the way, that NOKANJI without NOUNICODE only removes the non-Unicode Kanji sets (Shift-JIS, EUC-JP, JIS-7, etc). Kanji is still representable in UCS-2 and UTF-8.

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5. APC EXECUTION

The Kermit CONNECT and INPUT commands are coded to execute Application Program Command escape sequences from the host:

  <ESC>_<text><ESC>\

where <text> is a C-Kermit command, or a list of C-Kermit commands separated by commas, up to about 1K in length.

To date, this feature has been included in the OS/2, Windows, VMS, OS-9, and Unix versions, for which the symbol:

  CK_APC

is defined automatically in ckuusr.h. For OS/2, APC is enabled at runtime by default, for UNIX it is disabled. It is controlled by the SET TERMINAL APC command. Configuring APC capability into a version that gets it by default (because CK_APC is defined in ckuusr.h) can be overridden by including:

  -DNOAPC

on the CC command line.

C-Kermit's autodownload feature depends on the APC feature, so deconfiguring APC also disables autodownload (it doesn't use APC escape sequences, but uses the APC switching mechanism internally).

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6. PROGRAM SIZE

SECTION CONTENTS

  6.1. Feature Selection
  6.2. Changing Buffer Sizes
  6.3. Other Size-Related Items
  6.4. Space/Time Tradeoffs

(Also see Section 4)

Each release of C-Kermit is larger than the last. On some computers (usually old ones) the size of the program prevents it from being successfully linked and loaded. On some others (also usually old ones), it occupies so much memory that it is constantly swapping or paging. In such cases, you can reduce C-Kermit's size in various ways, outlined in this section. The following options can cut down on the program's size at compile time by removing features or changing the size of storage areas.

If you are reading this section because all you want is a small, fast, quick-to-load Kermit file-transfer application for the remote end of your connection, and the remote end is Unix based, take a look at G-Kermit:

  http://www.columbia.edu/kermit/gkermit.html

6.1. Feature Selection

  #define NODEBUG

The following table shows the savings achieved when building C-Kermit 8.0 (Beta.04) with selected feature-deselection switches on an Intel-based PC with Red Hat Linux 7.0 and gcc 2.96. The sizes are for non-security builds. The fully configured non-security build is 2127408 bytes.

Option	Size	Savings	Effect
NOICP	545330	74.4%	No Interactive Command Parser (command-line only)
NOLOCAL	1539994	27.6%	No making connections.
NOXFER	1551108	27.1%	No file transfer.
IKSDONLY	1566608	26.4%	Internet Kermit Server only.
NOCSETS	1750097	17.7%	No character-set conversion.
NOSPL	1800293	15.4%	No Script Programming Language.
NONET	1808575	15.0%	No making network connections.
NOUNICODE	1834426	13.8%	No Unicode character-set conversion.
NOHELP	1837877	13.6%	No built-in help text.
NODEBUG	1891669	11.1%	No debug log.
NOFRILLS	1918966	9.8%	No "frills".
NOFTP	1972496	7.3%	No FTP client.
NODIAL	1984488	6.7%	No automatic modem dialing.
NOPUSH	2070184	2.7%	No shell access, running external programs, etc.
NOIKSD	2074129	2.5%	No Internet Kermit Server capability.
NOHTTP	2082610	2.1%	No HTTP client.
NOFLOAT	2091332	1.7%	No floating-point arithmetic.
NOCHANNELIO	2095978	1.5%	No FOPEN/FREAD/FWRITE/FCLOSE, etc.
MINIDIAL	2098035	1.4%	No built-in support for many kinds of modems.
NOSERVER	2098987	1.3%	No server mode.
NOSEXP	2105898	1.0%	No S-Expressions.
NOPTY	2117743	0.5%	No pseudoterminal support.
NORLOGIN	2121089	0.3%	No RLOGIN connections.
NOOLDMODEMS	2124038	0.2%	No built-in support for old kinds of modems.
NOSSH	2125696	0.1%	No SSH command.

And here are a few combinations

Options	Size	Savings	Effect
NODEBUG NOICP NOCSETS NOLOCAL	281641	86.7%	No debug log, parser, character sets, or making connections.
NOICP NOCSETS NOLOCAL	376468	82.3%	No parser, character sets, or making connections.
NOICP NOCSETS NONET	427510	79.9%	No parser, character sets, or network connections.
NOSPL NOCSETS	1423784	33.1%	No script language, or character sets.

-DNOFRILLS removes various command synonyms; the following top-level commands: CLEAR, DELETE, DISABLE, ENABLE, GETOK, MAIL, RENAME, TYPE, WHO; and the following REMOTE commands: KERMIT, LOGIN, LOGOUT, PRINT, TYPE, WHO.

6.2. Changing Buffer Sizes

Two major factors affect Kermit's size: feature selection and buffer sizes. Buffer sizes affect such things as the maximum length for a Kermit packet, the maximum length for a command, for a macro, for the name of a macro, etc. Big buffer sizes are used when the following symbol is defined:

  BIGBUFOK

as it is by default for most modern platforms (Linux, AIX 4 and 5, HP-UX 10 and 11, Solaris, etc) in ckuusr.h. If your build does not get big buffers automatically (SHOW FEATURES tells you), you can include them by rebuilding with BIGBUFOK defined; e.g. in Unix:

  make xxxx KFLAGS=-DBIGBUFOK

where xxxx is the makefile target. On the other hand, if you want to build without big buffers when they normally would be selected, use:

  make xxxx KFLAGS=-DNOBIGBUF

There are options to control Kermit's packet buffer allocations. The following symbols are defined in ckcker.h in such a way that you can override them by redefining them in CFLAGS:

  -DMAXSP=xxxx - Maximum send-packet length.
  -DMAXRP=xxxx - Maximum receive-packet length.
  -DSBSIZ=xxxx - Total allocation for send-packet buffers.
  -DRBSIZ=xxxx - Total allocation for receive-packet buffers.

The defaults depend on the platform.

Using dynamic allocation (-DDYNAMIC) reduces storage requirements for the executable program on disk, and allows more and bigger packets at runtime. This has proven safe over the years, and now most builds (e.g. all Unix, VMS, Windows, and OS/2 ones) use dynamic memory allocation by default. If it causes trouble, however, then omit the -DDYNAMIC option from CFLAGS, or add -DNODYNAMIC.

6.3. Other Size-Related Items

1. Request a larger ("large" or "huge") compilation / code-generation model. This is needed for 16-bit PC-based UNIX versions (most or all of which fail to build C-Kermit 7.0 and later anyway). This is typically done with a -M and/or -F switch (see your cc manual or man page for details).

2. Some development systems support overlays. If the program is too big to be built as is, check your loader manual ("man ld") to see if an overlay feature is available. See the 2.10/2.11 BSD example in the UNIX makefile. (Actually, as of version 7.0, C-Kermit is too big to build, period, even with overlays, on 2.xx BSD).

3. Similarly, some small and/or segment-based architectures support "code mapping", which is similar to overlays (PDP11-based VENIX 1.0, circa 1984, was an example). See the linker documentation on the affected platform.

It is also possible to reduce the size of the executable program file in several other ways:

1. Include the -O (optimize) compiler switch if it isn't already included in your "make" entry (and if it works!). If your compiler supports higher levels of optimization (e.g. -O2 or higher number, -Onolimit (HP-UX), etc), try them; the greater the level of optimization, the longer the compilation and more likely the compiler will run out of memory. The the latter eventuality, some compilers also provide command-line options to allocate more memory for the optimizer, like "-Olimit number" in Ultrix.

2. If your platofrm supports shared libraries, change the make entry to take advantage of this feature. The way to do this is, of course, platform dependent; see the NeXT makefile target for an example. some platforms (like Solaris) do it automatically and give you no choice. But watch out: executables linked with shared libraries are less portable than statically linked executables.

3. Strip the program image after building ("man strip" for further info), or add -s to the LNKFLAGS (UNIX only). This strips the program of its symbol table and relocation information.

4. Move character strings into a separate file. See the 2.11 BSD target for an example.

6.4. Space/Time Tradeoffs

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7. MODEM DIALING

-DNODIAL removes automatic modem dialing completely, including the entire ckudia.c module, plus all commands that refer to dialing in the various ckuus*.c modules.

-DMINIDIAL leaves the DIAL and related commands (SET/SHOW MODEM, SET/SHOW DIAL) intact, but removes support for all types of modems except CCITT, Hayes, Unknown, User-defined, Generic-high-speed, and None (= Direct). The MINIDIAL option cuts the size of the dial module approximately in half. Use this option if you have only Hayes or CCITT modems and don't want to carry the baggage for the other types.

A compromise between full dialer support and MINIDIAL is obtained by removing support for "old" modems -- all the strange non-Hayes compatible 1200 and 2400 bps modems that C-Kermit has been carrying around since 1985 or so. To remove support for these modems, add -DNOOLDMODEMS to CFLAGS at compilation time.

Finally, if you keep support for old modems, you will notice that their names appear on the "set modem ?" menu. That's because their names are, by default, "visible". But the list is confusing to the younger generation, who have only heard of modems from the V.32bis-and-later era. If you want to be able to use old modems, but don't want their names cluttering up menus, add this to CFLAGS:

  -DM_OLD=1

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8. NETWORK SUPPORT

SECTION CONTENTS

  8.1. TCP/IP
  8.2. X.25
  8.3. Other Networks

C-Kermit supports not only serial-port and modem connections, but also TCP/IP and X.25 network connections. Some versions support other network types too like DECnet, LAT, NETBIOS, etc. If you define the following symbol:

  NONET

then all network support is compiled away.

8.1. TCP/IP

  8.1.1. Firewalls
  8.1.2. Compilation and Linking Problems
  8.1.3. Enabling Host Address Lists
  8.1.4. Enabling Telnet NAWS
  8.1.5. Enabling Incoming TCP/IP Connections
  8.1.6. Disabling SET TCP Options

C-Kermit's TCP/IP features require the Berkeley sockets library or equivalent, generally available on any Unix system, as well as in Windows 9x/NT, OS/2, VMS, AOS/VS, VOS, etc. The TCP/IP support includes built-in TELNET, FTP, and HTTP protocol. To select TCP/IP support, include -DTCPSOCKET in your makefile target's CFLAGS, or (in VMS) the appropriate variant (e.g. -DWOLLONGONG, -DMULTINET, -DEXCELAN, -DWINTCP, etc).

The VMS and/or early Unix third-party TCP/IP products are often incompatible with each other, and sometimes with different versions of themselves. For example, Wollongong reportedly put header files in different directories for different UNIX versions:

• in.h can be in either /usr/include/sys or /user/include/netinet.
• telnet.h can be in either /usr/include/arpa or /user/include/netinet.
• inet.h can be in either /usr/include/arpa or /user/include/sys.

In cases like this, use the -I cc command-line option when possible; otherwise it's better to make links in the file system than it is to hack up the C-Kermit source code. Suppose, for example, Kermit is looking for telnet.h in /usr/include/arpa, but on your computer it is in /usr/include/netinet. Do this (as root, or get the system administrator to do it):

  cd /usr/include/arpa
  ln /usr/include/netinet/telnet.h telnet.h

("man ln" for details about links.)

The network support for TCP/IP and X.25 is in the source files ckcnet.h, ckctel.c, ckctel.c, ckctel.h, ckcftp.c, with miscellaneous SHOW commands, etc, in the various ckuus*.c modules, plus code in the ck*con.c or ckucns.c (CONNECT command) and several other modules to detect TELNET negotiations, etc.

Within the TCPSOCKET code, some socket-level controls are included if TCPSOCKET is defined in the C-Kermit CFLAGS and SOL_SOCKET is defined in in the system's TCP-related header files, such as <sys/socket.h>. These are:

  SET TCP KEEPALIVE
  SET TCP LINGER
  SET TCP RECVBUF
  SET TCP SENDBUF

In addition, if TCP_NODELAY is defined, the following command is also enabled:

  SET TCP NODELAY (Nagle algorithm)

See the C-Kermit user documentation for descriptions of these commands.

8.1.1. Firewalls

One firewall method is called SOCKS, in which a proxy server allows users inside a firewall to access the outside world, based on a permission list generally stored in a file. SOCKS is enabled in one of two ways. First, the standard sockets library is modified to handle the firewall, and then all the client applications are relinked (if necessary, i.e. if the libraries are not dynamically loaded) with the modified sockets library. The APIs are all the same, so the applications do not need to be recoded or recompiled.

In the other method, the applications must be modified to call replacement routines, such as Raccept() instead of accept(), Rbind() instead of bind(), etc, and then linked with a separate SOCKS library. This second method is accomplished (for SOCKS4) in C-Kermit by including -DCK_SOCKS in your CFLAGS, and also adding:

  -lsocks

to LIBS, or replacing -lsockets with -lsocks (depending on whether the socks library also includes all the sockets entry points).

For SOCKS5, use -DCK_SOCKS5.

Explicit firewall support can, in general, not be a standard feature or a feature that is selected at runtime, because the SOCKS library tends to be different at each site -- local modifications abound.

The ideal situation occurs when firewalls are supported by the first method, using dynamically linked sockets-replacement libraries; in this case, all your TCP/IP client applications negotiate the firewall transparently.

8.1.2. Compilation and Linking Problems

Compilation errors might also have to do with the data type used for getsockopt() and setsockopt() option-length field. This is normally an int, but sometimes it's a short, a long, or an unsigned any of those, or a size_t. To fix the compilation problem, add -DSOCKOPT_T=xxx to the CFLAGS in your makefile target, where xxx is the appropriate type (use "man getsockopt" or grep through your system/network header files to find the needed type).

8.1.3. Enabling Host Address Lists

  HADDRLIST

8.1.4. Enabling Telnet NAWS

This appears to be needed at least on the AT&T 3B2, where in ckutio.c, the routine ttgwsiz() finds that the TIOCGWINSZ symbol is defined but lacks definitions for the corresponding winsize struct and its members ws_col and ws_row.

The UNIX version of C-Kermit also traps SIGWINCH, so it can send a NAWS to the Telnet server any time the local console terminal window size changes, e.g. when you stretch it with a mouse. The SIGWINCH-trapping code is enabled if SIGWINCH is defined (i.e. in signal.h). If this code should cause problems, you can disable it without disabling the NAWS feature altogether, by defining NOSIGWINCH at compile time.

8.1.5. Enabling Incoming TCP/IP Connections

If you want to disable incoming TCP/IP connections, then build C-Kermit with:

  -DNOLISTEN

8.1.6. Disabling SET TCP Options

  -DNOTCPOPTS

8.2. X.25

In UNIX, special makefile targets sunos4x25 and sunos41x25 (for SUNOS 4.0 and 4.1, respectively), or aix41x25, are provided to build in this feature, but they only work if conditions (a)-(c) are met. To request this feature, include -DSUNX25 (or -DIBMX25) in CFLAGS.

SUNX25 (or -DIBMX25) and TCPSOCKET can be freely mixed and matched, and selected by the user at runtime with the SET NETWORK TYPE command or SET HOST switches.

8.3. Other Networks

Provision is made in the organization of the modules, header files, commands, etc, for addition of new network types such as DECnet, X.25 for other systems (HP-UX, VMS, etc), and so on. Send email to kermit@columbia.edu if you are willing and able to work on such a project.

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9. EXCEPTION HANDLING

The C language setjmp/longjmp mechanism is used for handling exceptions. The jump buffer is of type jmp_buf, which almost everywhere is typedef'd as an array, in which case you should have no trouble compiling the exception-handling code. However, if you are building C-Kermit in/for an environment where jmp_buf is something other than an array (e.g. a struct), then you'll have to define the following symbol:

  JBNOTARRAY

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10. SECURITY FEATURES

Security, in the sense of secure authentication and strong encryption, can be built into versionf of C-Kermit for which the appropriate libraries and header files are available (Kerberos IV, Kerberos V, OpenSSL, SRP), as explained in great detail in the Kermit Security Reference. The following symbols govern C-Kermit's security features at build time:

NO_AUTHENTICATION

Means do not configure any TELNET AUTHENTICATION support. It implies NO_ENCRYPTION and undefines any of the auth and encrypt types. It does not undefine CK_SSL even though builds with CK_SSL cannot succeed without CK_AUTHENTICATION. (This will be supported in a future release. It will be needed to allow C-Kermit to be built only as an FTP client.)

NO_KERBEROS

Means do not compile in any KERBEROS support when CK_AUTHENTICATION has been defined.

NO_SRP

Do not compile in any SRP support when CK_AUTHENTICATION has been defined.

NO_SSL

Do not compile in any SSL/TLS support

NO_ENCRYPTION

Do not compile in any Telnet encryption support. It does not affect the use of SSL/TLS

NOSSH

Do not compile in any SSH support whether internal or external

CK_AUTHENTICATION

Telnet AUTHENTICATION support. (Also, required if SSL/TLS support is desired.) On most platforms this does not autodefine any authentication mechanisms such as Kerberos V, Kerberos IV, SRP, ... Those need to be defined separately.

CK_KERBEROS

Defined automatically when KRB4, KRB5, or KRB524 are defined. Implies that some version of Kerberos is in use.

KRB4

Should be defined when Kerberos IV support is desired.

KRB5

Should be defined when Kerberos V support is desired.

KRB524

Should be defined if both Kerberos V and Kerberos IV are used and the Kerberos IV support is provided by the MIT Kerberos IV compatibility library in the current Kerberos 5 distribution.

KRB5_U2U

Should be defined if KRB5 is defined and Kerberos 5 User to User mode is desired.

HEIMDAL

Should be defined if Kerberos V support is provided by HEIMDAL. Support for this option is not complete in C-Kermit 8.0. Anyone interested in working on this should contact kermit-support.

CK_SRP

Should be defined if SRP support is desired.

CK_ENCRYPTION

Should be defined if TELNET ENCRYPTION option support is desired. This option does not define any particular encryption types. That should be done by defining CK_DES or CK_CAST.

CK_DES

Should be defined if either DES or 3DES Telnet Encryption option support is desired.

LIBDES

If CK_DES is defined and DES support is being provided by either Eric Young's libdes.a or OpenSSL 0.9.6x or earlier, this option must be defined. If it is not defined, it will be assumed that DES support is provided by the MIT Kerberos IV libraries.

CK_CAST

Should be defined if CAST Telnet Encryption option support is desired

CK_SSL

Should be defined if SSL/TLS support (OpenSSL) is desired.

SSL_KRB5

If KRB5 is defined, and OpenSSL is built to support the Kerberos 5 ciphers, then you should define SSL_KRB5

NOSSLKRB5

If you are using OpenSSL 0.9.7 or higher and do not wish to build with support for Kerberos 5 TLS ciphers, this option must be defined.

ZLIB

If you are using OpenSSL 0.9.6 or higher and it has been compiled with support for ZLIB compression, this option should be defined to enable Kermit to properly enable the use of compression.

SSHCMD

Defined for C-Kermit to enable the use of external SSH clients from the Kermit command language

SSHBUILTIN

Defined for Kermit implementations that have integrated SSH support. Currently only Windows.

ANYSSH

Defined if either SSHCMD or SSHBUILTIN are defined.

CK_SNDLOC

Telnet Send Location support.

NOSNDLOC

Do not include Telnet Send Location support.

CK_XDISPLOC

Telnet X-Display Location support. Determines if the X-Display location information is sent to the Telnet server either via Telnet XDISPLOC or NEW-ENV options.

NOXDISPLOC

Do not include Telnet X-Display Location support.

CK_FORWARD_X

Telnet Forward X Windows Session Data option. Used to protect the privacy and integrity of X Windows Sessions when secure telnet sessions are in use.

NOFORWARDX

Do not include Telnet Forward X Windows Session Data option.

Besides the strong forms of security listed above, C-Kermit also embodies various internal security features, including:

NOPUSH

Compiling with the NOPUSH symbol defined removes all the "shell escape" features from the program, including the PUSH, RUN, and SPAWN commands, the "!" and "@" command prefixes, OPEN !READ, OPEN !WRITE, job control (including the SUSPEND command), the REDIRECT command, shell/DCL escape from CONNECT mode, as well as the server's execution of REMOTE HOST commands (and, of course, the ENABLE HOST command). Add NODISPO to also prevent acceptance of incoming MAIL or REMOTE PRINT files. For UNIX, also be sure to read Section 11 of the Unix C-Kermit Installation Instructions. about set[ug]id configuration. Additional restrictions can be enforced when in server mode; read about the DISABLE command in the user manual.

NOCCTRAP

Compiling with NOCCTRAP prevents the trapping of SIGINT by Kermit. Thus if the user generates a SIGINT signal (e.g. by typing the system's interrupt character), Kermit will exit immediately, rather than returning to its prompt.

NOPUSH and NOCCTRAP together allow Kermit to be run from restricted shells, preventing access to system functions.

[ C-Kermit Home ] [ Kermit Home ]

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11. ENABLING SELECT()

Kermit works best if it can do nonblocking reads, nondestructive input buffer checking, and millisecond sleeps. All of these functions can be accomplished by the select() function, which, unfortunately, is not universally available. Furthermore, select() is required if incoming TCP/IP connections are to be supported.

select() was introduced with Berkeley UNIX, rejected by AT&T for System V, but is gradually creeping in to all UNIX versions (and other operating systems too) by virtue of its presence in the sockets library, which is needed for TCP/IP. AT&T SVID for System V R4 includes select(), but that does not mean that all SVR4 implementations have it.

Furthermore, even when select() is available, it might work only on socket file descriptors, but not on others like serial ports, pipes, etc. For example, in AOS/VS and BeOS, it works only with file descriptors that were created by socket() and opened by connect() or accept().

Other alternatives include poll() and rdchk(). Only one of these three functions should be included. The following symbols govern this:

SELECT	Use select()	(BSD, or systems with sockets libraries)
CK_POLL	Use poll()	(System V)
RDCHK	Use rdchk()	(SCO XENIX and UNIX)

If your system supports the select() function, but your version of C-Kermit does not, try adding:

  -DSELECT

to the CFLAGS, and removing -DRDCHK or -DCK_POLL if it is there. If you get compilation errors, some adjustments to ck*tio.c and/or ck*net.c might be needed; search for SELECT (uppercase) in these files (note that there are several variations on the calling conventions for select()).

Various macros and data types need to be defined in order to use select(). Usually these are picked up from <types.h> or <sys/types.h>. But on some systems, they are in <sys/select.h>. In that case, add the following:

  -DSELECT_H

to the CFLAGS to tell C-Kermit to #include <sys/select.h>. A good indication that you need to do this would be if you get compile-time complaints about "fd_set" or "FD_SET" not being declared or defined.

In UNIX, the use of select() vs fork() in the CONNECT command is independent of the above considerations, and is governed by choosing a particular makefile target.

As of C-Kermit 7.0, select() is also the preferred control mechanism for the CONNECT command. Unfortunately, the structures used by the original UNIX CONNECT command, based on fork(), and those used by select(), are so different, it was not practical to implement them both in one module. So the select()-based CONNECT command module for UNIX is ckucns.c, and the fork-based one remains ckucon.c. To choose the fork-based one, which is more portable (but slower and more fragile), use "wermit" as the make target. To choose the select-based one, use "xermit". Only do this if you can verify that the CONNECT command works on serial connections and PIPE connections as well as TCP connections.

The select()-based Unix CONNECT module, ckucns.c, must be used if encryption is to be done, since the fork() version (ckucon.c) loses its ability to share vital state information between the two forks. Also note that the select() version is superior in many other ways too. For example, it recovers better from exterior killing, forced disconnections, etc, plus it goes faster.

SHOW VERSIONS tells whether the CONNECT module uses fork() or select().

C-Kermit 8.0 adds learned script capability, which depends on select(). All the "wermit" based targets (as opposed to "xermit") had NOLEARN added to them. Whenever changing a target over from wermit to xermit, also remember to remove NOLEARN.

[ C-Kermit Home ] [ Kermit Home ]

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12. I/O REDIRECTION

The REDIRECT command allows a local program to be run with its i/o redirected over the communications connection. Your version of C-Kermit has a REDIRECT command if it was built with the following CFLAG:

  -DCK_REDIR

This, in turn, is possible only if the underlying API is there. In the case of UNIX this is just the wait() system call, so all UNIX versions get this feature as of 6.0.192 (earlier versions needed a <sys/wait.h> header file defining the symbols WIFEXITED and WEXITSTATUS).

As of version 7.0, file transfer can be done using pipes and filters. To enable this feature, #define PIPESEND (and fill in the code). To disable on systems where it is normally enabled, define NOPIPESEND. This feature is, of course, also disabled by building with NOPUSH (or giving the "nopush" command at runtime).

C-Kermit 7.0 also adds the PIPE and SET HOST /COMMAND commands, which provide another form of redirection. This feature is selected with -DNETCMD. CK_RDIR must also be defined, since the same mechanisms are used internally.

[ C-Kermit Home ] [ Kermit Home ]

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13. FLOATING-POINT NUMBERS, TIMERS, AND ARITHMETIC

Floating-point support was added in C-Kermit 7.0.

Floating-point numbers are enabled internally, at least for use in high-precision file-transfer timers and statistics, unless the following symbol is defined at compile time:

  -DNOFLOAT

This might be necessary on old PCs that do not have built-in floating-point hardware.

When NOFLOAT is not defined, the following symbol tells which floating-point type to use:

  -DCKFLOAT=xxxx

The value is either "double" (normal for 32- and 16-bit architectures) or "float" (normal for 64-bit architectures).

C-Kermit can be configured to use high-precision file-transfer timers for more accurate statistics. This feature is enabled with:

  -DGFTIMER

and disabled with:

  -DNOGFTIMER

If you try to build with -DGFTIMER but you get compilation errors, either fix them (and send email to kermit@columbia.edu telling what you did), or else give up and use -DNOGFTIMER (or -DNOFLOAT) instead. Hint: depending on your machine architecture, you might have better luck using double than float as the data type for floating-point numbers, or vice versa. Look in ckcdeb.h for the CKFLOAT definition.

Floating-point arithmetic is also supported in the script programming language. First via the \fpp...() functions, such as \fppadd(), which adds two floating-point numbers, second in S-Expressions. Addition, subtraction, multiplication, and division are always available. But other functions such as logs, raising to powers, sines and cosines, etc, require the C Math library. To include user-level floating-point math you must put:

  -DFNFLOAT

and in Unix you must link with the Math library:

  LIBS=".... -lm"

In K95 and VMS, FNFLOAT is defined automatically if CKFLOAT is defined. In Unix, however, FNFLOAT must be added to each makefile target individually, because of the special linking instructions that must also be added to each target.

Note: S-Expressions require FNFLOAT.

[ C-Kermit Home ] [ Kermit Home ]

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14. SPECIAL CONFIGURATIONS

As of C-Kermit 7.0, if you build C-Kermit normally, but with -DNOICP (No Interactive Command Parser), you get a program capable of making serial connections (but not dialing) and network connections (if TCPSOCKET or other network option included), and can also transfer files using Kermit protocol, but only via autodownload/upload. Furthermore, if you call the executable "telnet", it will act like Telnet -- using the command-line options. However, in this case there is nothing to escape back to, so if you type Ctrl-\c, it just prints a message to this effect.

You can also build C-Kermit with -DNOXFER, meaning omit all the file-transfer features. This leaves you with a scriptable communications program that is considerably smaller than the full C-Kermit.

[ C-Kermit Home ] [ Kermit Home ]

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APPENDIX I: SUMMARY OF COMPILE-TIME OPTIONS

These are the symbols that can be specified on the cc command line, listed alphabetically. Others are used internally, including those taken from header files, those defined by the compiler itself, and those inferred from the ones given below. Kermit's SHOW VERSIONS command attempts to display most of these. See ckcdeb.h and ckcnet.h for inference rules. For example SVR3 implies ATTSV, MULTINET implies TCPSOCKET, and so on.

Here is the complete list of the Kermit-specific compile-time switches:

ACUCNTRL	Select BSD 4.3-style acucntrl() bidirectional tty control.
aegis	Build for Apollo Aegis (predefined on Apollo systems).
AIX370	Build for IBM AIX/370 for IBM mainframes.
AIXESA	Build for IBM AIX/ESA for IBM mainframes.
AIXPS2	Build for IBM AIX 3.0 for PS/2 series (never formally released).
AIXRS	Build for IBM AIX 3.x on RS/6000.
AIX41	Build for IBM AIX 4.x on RS/6000.
AMIGA	Build for Commodore Amiga with Intuition OS.
ATT6300	Build for AT&T 6300 PLUS.
ATT7300	Build for AT&T 7300 UNIX PC (3B1).
ATTSV	Build for AT&T System III or V UNIX.
AUX	Build for Apple A/UX for the Macintosh.
BIGBUFOK	OK to use big buffers - "memory is not a problem"
BPS_xxxx	Enable SET SPEED xxxx
BSD29	Build for BSD 2.9 or 2.10.
BSD4	Build for BSD 4.2.
BSD41	Build for BSD 4.1.
BSD43	Build for BSD 4.3.
BSD44	Build for BSD 4.4.
C70	Build for BBN C/70.
CIE	Build for CIE Systems 680/20.
CKCONINTB4CB	Work around prompt-disappears after escape back from CONNECT.
CKLEARN	Build with support for learned scripts.
CKLOGDIAL	Enable connection log.
CKMAXPATH	Maximum length for a fully qualified filename.
CKREGEX	(misnomer) Include [...] or {xxx,xxx,xxx} matching in ckmatch().
CKSYSLOG	Enable syslogging.
CK_ANSIC	Enable ANSI C constructs - prototypes, etc.
CK_ANSILIBS	Use header files for ANSI C libraries.
CK_APC	Enable APC execution by CONNECT module.
CK_CURSES	Enable fullscreen file transfer display.
CK_DSYSINI	Use system-wide init file, with name supplied by Kermit.
CK_DTRCD	DTR/CD flow control is available.
CK_FAST	Build with fast Kermit protocol defaults.
CK_FORK_SIG	UNIX only: signal() number for CONNECT module forks.
CK_IFRO	IF REMOTE command is available (and can run in remote mode).
CK_INI_A	System-wide init file takes precedence over user's.
CK_INI_B	User's init file takes precedence over the system-wide one.
CK_LABELED	Include support for SET FILE TYPE LABELED.
CK_LBRK	This version can send Long BREAK.
CK_LINGER	Add code to turn of TCP socket "linger" parameter.
CK_MKDIR	This version has a zmkdir() command to create directories.
CK_NAWS	Include TELNET Negotiate About Window Size support.
CK_NEWTERM	Use newterm() rather than initscr() to initialize curses.
CK_PAM	Include PAM authentication (might also require -lpam).
CK_PCT_BAR	Fullscreen file transfer display should include "thermometer".
CK_POLL	System-V or POSIX based UNIX has poll() function.
CK_POSIX_SIG	Use POSIX signal handing: sigjmp_buf, sigsetjmp, siglongjmp.
CK_READ0	read(fd,&x,0) can be used to test TCP/IP connections.
CK_REDIR	Enable the REDIRECT command.
CK_RESEND	Include the RESEND command (needs zfseek() + append).
CK_RTSCTS	RTS/CTS flow control is available.
CK_SHADOW	Include support for shadow passwords (e.g. for IKSD authentication).
CK_SOCKBUF	Enable TCP socket-buffer-size-increasing code.
CK_SOCKS	UNIX only: Build with socks library rather than regular sockets
CK_SOCKS5	UNIX only: Build with socks 5 lib rather than regular sockets
CK_SPEED	Enable control-character unprefixing.
CK_SYSINI="xxxxx"	Quoted string to be used as system-wide init file name.
CK_TIMERS	Build with support for dynamically calculated packet timeouts.
CK_TMPDIR	This version of Kermit has an isdir() function.
CK_TTYFD	Defined on systems where the communications connection file descriptor (ttyfd) can be passed to other processes as a command-line argument via \v(ttyfd).
CK_URL	Parse URLs as well as hostnames, etc.
CK_XONXOFF	Xon/Xoff flow control available.
CK_XYZ	Include support for XYZMODEM protocols.
CK_WREFRESH	Curses package includes wrefresh(),clearok() for screen refresh.
CKFLOAT=type	Floating-point data type, "double" or "float".
CKTYP_H=xxx	Force include of xxx as <types.h> file.
CLSOPN	When hanging up a tty device, also close and reopen it.
CMDDEP	Maximum recursion depth for self-referential user-defined fn's.
COHERENT	Build for Mark Williams Coherent UNIX
CONGSPD	Define if this version has congspd() routine in ck?tio.c
datageneral	Build for Data General AOS/VS or AOS/VS II
DCLPOPEN	popen() is available but needs to be declared
DEC_TCPIP	Build with support for DEC TCP/IP (UCX) for (Open)VMS
DGUX430	Build for DG/UX 4.30
DGUX540	Build for DG/UX 5.40
DEFPAR=x	Default parity, 0, 'e', 'o', 'm', or 's'.
DFTTY=xxx	Default communications device name.
DIRENT	UNIX directory structure to be taken from <dirent.h>.
DIRPWDRP	Prompt for password in REMOTE CWD command.
DTILDE	Include UNIX ~ notation for username/home-directory
DYNAMIC	Allocate file transfer packet buffers dynamically with malloc.
ENCORE	Build for Encore Multimax computers.
EXCELAN	Build with excelan TCP/IP.
FNFLOAT	Include floating-point math functions (logs, sin, cos, exp, etc)
FT18	Build for Fortune For:Pro 1.8.
FT21	Build for Fortune For:Pro 2.1.
GEMDOS	Build for Atari ST GEMDOS.
GFTIMER	Use high-precision floating-point file-transfer timers.
GID_T=xxx	Group IDs are of type xxx (usually int, short, or gid_t).
HADDRLIST	If gethostbyname() hostent struct contains a list of addresses.
HDBUUCP	Build with support for Honey DanBer UUCP.
HPUX	Build for Hewlett Packard HP-UX.
HPUX9	Build for Hewlett Packard HP-UX 9.x.
HPUX10	Build for Hewlett Packard HP-UX 10.x.
HWPARITY	Define if this version can SET PARITY HARDWARE { EVEN, ODD...}
I386IX	Build for Interactive System V R3.
IFDEBUG	Add IF stmts "if (deblog)" before "debug()" calls.
INADDRX	TCP/IP inet_addr() type is struct inaddr, not unsigned long.
INTERLAN	Build with support for Racal/Interlan TCP/IP.
ISDIRBUG	System defs of S_ISDIR and S_ISREG have bug, define ourselves.
ISIII	Build for Interactive System III.
IX370	Build for IBM IX/370.
KANJI	Build with Kanji character-set translation support.
LCKDIR	UUCP lock directory is /usr/spool/uucp/LCK/.
LFDEVNO	UUCP lockfile name uses device numbers, as in SVR4.
LINUXFSSTND	For Linux, use FSSTND UUCP lockfile conventions (default).
LOCK_DIR=xxx	UUCP lock directory is xxx (quoted string).
LOCKF	Use lockf() (in addition to lockfiles) on serial lines
LONGFN	BSD long filenames supported using <dir.h> and opendir().
LYNXOS	Build for Lynx OS 2.2 or later (POSIX-based).
MAC	Build for Apple Macintosh with Mac OS.
MATCHDOT	Make wildcards match filenames that start with period (.)
MAXRP=number	Maximum receive-packet length.
MAXSP=number	Maximum send-packet length.
MDEBUG	Malloc-debugging requested.
MINIDIAL	Minimum modem dialer support: CCITT, Hayes, Unkown, and None.
MINIX	Build for MINIX.
MIPS	Build for MIPS workstation.
MULTINET	Build with support for TGV MultiNet TCP/IP (VAX/VMS).
M_UNIX	Defined by SCO.
NAP	The nap() is available (conflicts with SELECT and USLEEP)
NAPHACK	The nap() call is available but only as syscall(3112,...)
NDIR	BSD long filenames supported using <ndir.h> and opendir().
NDGPWNAM	Don't declare getpwnam().
NDSYSERRLIST	Don't declare sys_errlist[].
NEEDSELECTDEFS	select() is avaible but we need to define FD_blah ourselves.
NETCMD	Build with support for SET HOST /COMMAND and PIPE commands.
NEXT	Build for NeXT Mach 1.x or 2.x or 3.0, 3.1, or 3.2.
NEXT33	Build for NeXT Mach 3.3.
NOANSI	Disable ANSI C function prototyping.
NOAPC	Do not include CK_APC code.
NOARROWKEYS	Exclude code to parse ANSI arrow-key sequences.
NOB_xxxx	Disable SET SPEED xxxx
NOBIGBUF	Override BIGBUFOK when it is the default
NOBRKC	Don't try to refer to t_brkc or t_eof tchars structure members.
NOCKFQHOSTNAME	Exclude code to get fully qualified hostname in case it causes core dumps.
NOCCTRAP	Disable Control-C (SIGINT) trapping.
NOCKSPEED	Disable control-prefix removal feature (SET CONTROL).
NOCKTIMERS	Build without support for dynamic timers.
NOCKXYZ	Overrides CK_XYZ.
NOCKREGEX	Do not include [...] or {xxx,xxx,xxx} matching in ckmatch().
NOCMDL	Build with no command-line option processing.
NOCOTFMC	No Close(Open()) To Force Mode Change (UNIX version).
NOCSETS	Build with no support for character set translation.
NOCYRIL	Build with no support for Cyrillic character set translation.
NOCYRILLIC	Ditto.
NODEBUG	Build with no debug logging capability.
NODIAL	Build with no DIAL or SET DIAL commands.
NODISPO	Build to always refuse incoming MAIL or REMOTE PRINT files.
DNODISPLAY	Build with no file-transfer display.
NOESCSEQ	Build with no support for ANSI escape sequence recognition.
NOFAST	Do not make FAST Kermit protocol settings the default.
NOFDZERO	Do not use file descriptor 0 for remote-mode file transfer.
NOFILEH	Do not #include <sys/file.h>.
NOFLOAT	Don't include any floating-point data types or operations.
NOFRILLS	Build with "no frills" (this should be phased out...)
NOFTRUNCATE	Include this on UNIXes that don't have ftruncate().
NOGETUSERSHELL	Include this on UNIXes that don't have getusershell().
NOGFTIMER	Don't use high-precision floating-point file-transfer timers.
NOHEBREW	Build with no support for Hebrew character sets.
NOHELP	Build with no built-in help.
NOIKSD	Build with IKSD support excluded.
NOINITGROUPS	Include this on UNIXes that don't have initgroups().
NOICP	Build with no interactive command parser.
NOJC	Build with no support for job control (suspend).
NOKANJI	Build with no support for Japanese Kanji character sets.
NOKVERBS	Build with no support for keyboard verbs (\Kverbs).
NOLATIN2	Build with no ISO Latin-2 character-set translation support.
NOLEARN	Build with no support for learned scripts.
NOLINKBITS	Use of S_ISLNK and _IFLNK untrustworthy; use readlink() instead.
NOLOCAL	Build without any local-mode features: No Making Connections.
NOLOGDIAL	Disable connection log.
NOLOGIN	Build without IKSD (network login) support.
NOLSTAT	Not OK to use lstat().
NOMDMHUP	Build without "modem-specific hangup" (e.g. ATH0) feature.
NOMHHOST	Exclude the multihomed-host TCP/IP code (if compilcation errors)
NOMINPUT	Build without MINPUT command.
NOMSEND	Build with no MSEND command.
NONAWS	Do not include TELNET Negotiate About Window Size support.
NONET	Do not include any network support.
NONOSETBUF	(See NOSETBUF)
NOPARSEN	Build without automatic parity detection.
NOPIPESEND	Disable file transfer using pipes and filters.
NOPOLL	Override CK_POLL definition.
NOPOPEN	The popen() library call is not available.
NOPURGE	Build with no PURGE command.
NOPUSH	Build with no escapes to operating system.
NOREALPATH	In UNIX, realpath() function is not available.
NORECALL	Disable the command-recall feature.
NOREDIRECT	Disable REDIRECT command.
NORENAME	Don't use rename() system call, use link()/unlink() (UNIX).
NORESEND	Build with no RESEND command.
NORETRY	Build with no command-retry feature.
NOSCRIPT	Build with no SCRIPT command.
NOSELECT	Don't try to use select().
NOSERVER	Build with no SERVER mode and no server-related commands.
NOSETBUF	Don't make console writes unbuffered.
NONOSETBUF	DO make console writes unbuffered.
NOSETREU	setreuid() and/or setregid() not available.
NOSHOW	Build with no SHOW command (not recommended!).
NOSIGWINCH	Disable SIGWINCH signal trapping.
NOSPL	Build with no script programming language.
NOSTAT	Don't call stat() from mainline code.
NOSYMLINK	Include this for UNIXes that don't have readlink().
NOSYSIOCTLH	Do not #include <sys/ioctl.h>.
NOSYSTIMEH	Co not include <sys/time.h>.
NOSYSLOG	Disable syslogging code.
NOTCPOPTS	Build with no SET TCP options or underlying support.
NOTLOG	Build with no support for transaction logging.
NOTM_ISDST	Struct tm has no tm_isdst member.
NOUNICODE	Build with no support for Unicode character-set translation.
NOURL	Don't parse URLs
NOUUCP	Build with no UUCP lockfile support (dangerous!).
NOWARN	Make EXIT WARNING be OFF by default (otherwise it's ON).
NOWREFRESH	Override built-in definition of CK_WREFRESH (q.v.).
NOXFER	Build with no Kermit or other file-transfer protocols.
NOXMIT	Build with no TRANSMIT command.
NOXPRINT	Disables transparent print code.
OLDMSG	Use old "entering server mode" message (see ckcmai.c).
OLINUXHISPEED	Build in old Linux hi-serial-speed code (for Linux <= 1.0).
OPENBSD	Build for OpenBSD.
OS2	Build for OS/2.
OSF	Build for OSF/1.
OSFPC	Build for OSF/1 on a PC.
OSF32	Digital UNIX 3.2 or later.
OSF40	Build for Digital UNIX 4.0.
OSF50	Build for Digital UNIX 5.0.
OSK	Build for OS-9.
OXOS	Build for Olivetti X/OS 2.3.
PCIX	Build for PC/IX
PID_T=xxx	Type for pids is xxx (normally int or pid_t).
POSIX	Build for POSIX: use POSIX header files, functions, etc.
_POSIX_SOURCE	Disable non-POSIX features.
PROVX1	Build for Venix 1.0 on DEC Professional 3xx.
PTX	Build for Dynix/PTX
PWID_T=xxx	getpwid() type is xxx.
RBSIZ=xxx	Define overall size of receive-packet buffer (with DYNAMIC).
RDCHK	rdchk() system call is available.
RENAME	rename() system call is available (UNIX).
RTAIX	Build for AIX 2.2.1 on IBM RT PC.
RTU	Build for Masscomp / Concurrent RTU.
SAVEDUID	BSD or other non-AT&T UNIX has saved-setuid feature.
SBSIZ=xxx	Define overall size of send-packet buffer (use with DYNAMIC).
SDIRENT	Directory structure specified in <sys/dirent.h>.
SELECT	select() function available (conflicts with RDCHK and CK_POLL)
SELECT_H	Include <sys/select.h> for select()-releated definitions.
SETEUID	BSD 4.4-style seteXid() functions available.
SIG_V	Type for signal() is void. Used to override normal assumption.
SIG_I	Type for signal() is int. Used to override normal assumption.
SOCKOPT_T	Override default data type for get/setsockopt() option length.
SOLARIS	Build for Solaris.
SOLARIS25	Build for Solaris 2.5 or later.
SONYNEWS	Build for Sony NEWS-OS.
STERMIOX	<sys/termiox.h> is available.
STRATUS	Build for Stratus VOS.
STRATUSX25	Include Stratus VOS X.25 support.
SUN4S5	Build for SUNOS 4.x in the System V R3 environment.
SUNOS4	Build for SUNOS 4.0 in the BSD environment.
SUNOS41	Build for SUNOS 4.1 in the BSD environment.
SUNX25	Build with support for SunLink X.25.
SVR3	Build for AT&T System V Release 3.
SVR3JC	Allow job control support on System V Release 3 UNIX versions.
SVR4	Build for AT&T System V Release 4.
SW_ACC_ID	UNIX only -- swap real & effective ids around access() calls.
sxaE50	Build for PFU Compact A Series SX/A TISP.
SYSLOGLEVEL=n	Force syslogging at given level.
SYSTIMEH	Include <sys/time.h>.
SYSUTIMEH	Include <sys/utime.h> for setting file dates (88OPEN)
TCPSOCKET	Build with support for TCP/IP via Berkeley sockets library.
TERMIOX	<termiox.h> header file is available (mostly SVR4).
TNCODE	Include TELNET-specific code.
TOWER1	Build for NCR Tower 1632 with OS 1.02.
TRS16	Build for Tandy 16/6000.
UID_T=xxx	Type for uids is xxx (normally int or uid_t).
UNIX	Must be defined for all UNIX versions.
UNIX351M	AT&T UNIX 3.51m on the AT&T 7300 UNIX PC.
USE_ARROWKEYS	Include code to parse ANSI arrow-key sequences.
USE_LSTAT	OK to use lstat().
USE_MEMCPY	Define this if memcpy()/memset()/memmove() available.
USE_STRERROR	Define this if strerror() is available.
USLEEP	usleep() system call available (conflicts with NAP & SELECT).
UTEK	Build for Tektronix workstations with UTEK OS.
UTIMEH	Include <utime.h> for setting file dates (SVR4, POSIX)
UTS24	Build for Amdahl UTS 2.4.
V7	Build for Version 7 UNIX.
VMS	Build for VAX/VMS.
VOID=xxx	VOID type for functions (int or void).
VXVE	Build for CDC VX/VE 5.2.1.
WAIT_T=xxx	Type of argument passed to wait().
WINTCP	Build with Wollongong VAX/VMS TCP/IP (implies TCPSOCKET)
WOLLONGONG	Build with Wollongong UNIX TCP/IP (implies TCPSOCKET)
XENIX	Build for Xenix (SCO, Tandy, others).
XNDIR	Support for BSD long filenames via <sys/ndir.h>.
XYZ_INTERNAL	Support for XYZMODEM protocols is internal, not external.
ZFCDAT	Define this if zfcdat() function is available in Kermit.
ZILOG	Build for Zilog ZEUS.
ZJDATE	Has zjdate() function that converts date to Julian format.
XPRINT	Transparent print code included in CONNECT module.

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