JNOS Commands Manual - The T Commands
The T Command Set
tail <filename> Tail displays the last 20 (twenty) lines from <filename>. See also the taillog command. taillog Displays the last 20 (twenty) lines from the log file. tcp <subcommand> These commands are used for the Transmission Control Protocol service. All TCP parameters are configurable per interface. Commands of the form 'tcp <command>' set the default or global values. Use the 'ifconfig <iface> tcp <command>' form to set or show the interface- specific values. To set the system default TCP parameters, you must do so BEFORE attaching interfaces. After attachment, you must use the 'ifconfig <iface> tcp' command form to show or change values for that interface. Notes: Attempting outgoing connections to addresses without an existing route results in Error number 219. tcp access <permit|deny|delete> <ipaddr[/bits]|all> [loport [hiport]] Display or set tcp access controls, which determine which TCP services (ports) are accessible to which IP addresses. If no tcp access commands are issued, the default behavior is to permit all hosts to access all ports. But once a TCP access command is entered, all other ports and addresses are denied unless specifically permitted by subsequent tcp access commands. This subcommand adds or deletes an access control entry maintained in an internal table. Incoming tcp packets are compared with the table entries, in the order that they were added, to determine if access will be granted. Access is granted only if an entry with matching ipaddr or range, and ports, is found with "permit" set before either a match with "deny" set if found, or the end of the table is reached. The optional /bits suffix to the ipaddr specifies how many leading bits in the ipaddr are to be considered significant in the address comparisons. If not specified, 32 bits (i.e., full significance) is assumed. All addresses can be specified by "all". Loport and hiport specify the port or range of TCP ports for which the access control command applies. If "all" is given as the loport, or if no port range is specified, all ports are assumed, i.e., 1 to 65534. "tcp access" will display the table of current access control entries. Access commands should be entered from the most specific ipaddr to the least specific, since the first match (permit or deny) encountered in the internal table is definitive. #Example: #Allow a specific AMPRnet host SMTP access tcp access permit 44.76.1.199 25 #but deny all other services to him tcp access deny 44.76.1.199 #Allow all other AMPRnet hosts full access to TCP services tcp access permit 44.76.1/24 all #Allow a specific subnet access to ports 1 through 25, #which includes echo, discard, ftp, telnet, and smtp. tcp access permit 23.1.46/24 1 25 #Note that all other hosts not matched above, are denied access tcp blimit [<value>] Default: 31 Display or set the default tcp retransmission backoff limit. Normally each successive tcp retransmission is delayed a time value that increases exponentially or linearly. The backoff limit <value> serves to set the maximum backoff delay allowed. See also tcp timertype and tcp maxwait. tcp clean Reset all tcp connections that are in a "FIN wait 2" state. This is useful to release memory resources held by JNOS for connections that were not properly closed. tcp irtt [<milliseconds>] Display or set the initial round trip time estimate, in milliseconds, to be used for new TCP connections until they can measure and adapt to the actual value. The default is 5000 milliseconds (5 seconds). Increasing irtt when operating over slow channels will avoid the flurry of re-transmissions that would otherwise occur as the smoothed estimate settles down at the correct value. Note that this command should be given before servers are started in order for it to have effect on incoming connections. TCP also keeps a cache of measured round trip times and mean deviations (MDEV) for current and recent destinations. Whenever a new TCP connection is opened, the system first looks in this cache. If the destination is found, the cached IRTT and MDEV values are used. If not, the default IRTT value mentioned above is used, along with a MDEV of 0. This feature is fully automatic, and it can improve performance greatly when a series of connections are opened and closed to a given destination (e.g. a series of FTP file transfers or directory listings). tcp kick <tcb_addr> If there is unacknowledged data on the send queue of the specified TCB, this command forces an immediate retransmission. <tcb addr> can be found with the 'tcp status' command. tcp maxwait [<msec>] Set or show the maximum time for retry timeout in milliseconds. Default = 0, no maximum. tcp mss [<size>] Display or set the TCP Maximum Segment Size in bytes that will be sent on all outgoing TCP connect request (SYN segments). This tells the remote end the size of the largest segment (packet) it may send. Changing MSS affects only future connections; existing connections are unaffected. tcp reset <tcb_addr> Deletes the TCP control block at the specified address. tcp retries [<num>] Display or set the number of retries before a tcp connection will be reset. Default is 10. This is useful to eliminate idle connections that have not been properly shut down. If set to zero, there is no maximum, i.e. a connection will never retry out. tcp rtt <tcb_addr> <milliseconds> Replaces the automatically computed round trip time in the specified TCB with the rtt in milliseconds. This command is useful to speed up recovery from a series of lost packets since it provides a manual bypass around the normal backoff retransmission timing mechanisms. tcp status [<tcb_addr> | all] Without arguments, displays several TCP-level statistics, plus a summary of all existing TCP connections, including TCB address, send and receive queue sizes, local and remote sockets, and connection state. If <tcb addr> is specified, a more detailed dump of the specified TCB is generated, including send and receive sequence numbers and timer information. If "all" is given, the summary will also include TCBs in a listening state (awaiting a connection). In this case, a (S) will indicate that a server process is to be spawned when a connection occurs. tcp syndata [yes | NO] Display or set the tcp syn + data piggybacking flag. Some tcp systems cannot handle syn + data together. tcp timertype [linear | exponential] Display the current setting or set the timer type backoff algorithm. Default is linear. tcp trace [yes | NO] Display or set the tcp trace flag on or off. tcp window [<size>] Displays or sets the default receive window size in bytes to be used by TCP when creating new connections. Existing connections are unaffected. telnet <host> [<port_number>] The 'telnet' command allows you to initiate a connection using the Telnet protocol. The end result is much the same as doing an AX.25 connect in most cases, but you'll be taking advantage of the attributes of the TCP/IP protocols. See also the descriptions of the "echo" and "eol" commands. term The term command is used to configure TCP acess to local async ports. It is only available if JNOS was compiled with TERMSERVER #define'd. Then if 'start term' is issued, connects to TCP port 5000 (default) will be asked the term password if one was defined, then asked an interface name (unless just one term interface was defined.) After these questions are answered satisfactorily, whatever is received from the tcp connection is sent to the interface, and whatever is received from the interface is sent to the tcp connection. term iface [<iface> options...] Displays the list of interfaces accessible via term, or establishes a term interface and its operating parameters. term iface <iface> 7bit [OFF | on] Displays or changes the settings of the flag which causes term to apply a mask of 0x7F to all characters read during the term session. term iface <iface> break [<integer>] Displays or changes the value of the character code which, when read from the tcp input stream, causes term to send a BREAK to the associated serial device. The default is -1, i.e., disabled. Example: term iface mdm1 break 3 will interpret ASCII ^C as a send-break character. term iface <iface> cronly [OFF | on] Displays or changes the setting of the flag which causes term to ignore a newline (LF) read immediately after a CR is read from the tcp input stream. Note that if the nlcr option is in effect, a CRLF sequence is translated into a CRCR sequence, since the nlcr option is applied before the cronly option. term iface <iface> drop Deletes the interface <iface> from the list of interfaces accessible to term. The interface must not be in use by a term process. term iface <iface> flushwait [<#ms>] Default: 0 Displays or changes the number of milliseconds after which any non-newline-terminated input from the serial port, is flushed so that it becomes visible to the term user. The default value is 0, meaning that no flushing is done. A flushwait value of 500 ms is a good value to use when it is important to see, for example, login prompts that are not followed by a CR. term iface <iface> nlcr [OFF | on] Displays or changes the setting of the flag which causes term to translate a newline read from the tcp input stream, into a CR to be sent to the serial interface. term iface <iface> noecho [OFF | on] Displays or changes the setting of the flag which causes telnet echoing to be turned off for the duration of a term session. term iface <iface> noopt [OFF | on] Displays or changes the setting of the flag which causes telnet option processing to be turned off for the duration of the a term session. term password string Sets the term facility password to the provided string. The default is no password required. start term [port#] starts the server term iface <iface> winkdtr [OFF | on] Displays or changes the setting of the flag which causes DTR to be deasserted for one second, at the start of a term session. trace [<iface> [off | <btio> [outfile]] Controls packet tracing by the interface drivers. Specific bits enable tracing of the various interfaces and the amount of information produced. Tracing is controlled on a per-interface basis; without arguments, 'trace' gives a list of all defined interfaces and their tracing status. Output can be limited to a single interface by specifying it, and the control flags can be changed by specifying them as well. Trace control flags may be followed by <outfile>, a path to a disk file to contain the tracing output. The flags are given as a hexadecimal number which is interpreted as follows: B - Broadcast & RawDump selector 1 - Broadcast filter flag. If set, only packets specifically addressed to this node will be traced; broadcast packets will not be displayed. 2 - If this bit is set, a "raw" dump style is selected, for those interfaces which support it (e.g., ppp). 4 - If this bit is set, include polls in the output trace of polled-kiss interfaces. T - Controls type of tracing: 0 - Protocol headers are decoded, but data is not displayed 1 - Protocol headers are decoded, and data (but not the headers themselves) are displayed as ASCII characters, 64 characters per line. Unprintable characters are displayed as periods. 2 - Protocol headers are decoded, and the entire packet (headers AND data) is also displayed in hexadecimal and ASCII, 16 chars per line. 3 - A minimal display of headers and data is produced, provided JNOS was compiled with MONITOR #define'd. I - Enable tracing of input packets if 1, disable if 0 O - Enable tracing of output packets if 1, disable if 0 Example: # Trace all packets on port1 and display with headers: trace port1 0111 # Trace all lan non-broadcast received packets to a file: trace lan 1210 d:\lan_ipt.trc ttylink <host> [<port_number>] Default: 87 The 'ttylink' command starts a tcp protocol session with <host> using the split screen mode. Also see the telnet command.
(Courtesy KBNorton Computer Services)