rtelnet

SOCKS client version of telnet

Syntax:

rtelnet [-8] [-c] [-d] [-E] [-e escape_char]
        [-L] [-N] [-n tracefile] [-P policy]
        [-S tos] [host [port]]

Options:

-8

Allow an eight-bit input data path at all times. Without this option, parity bits are stripped whenever the remote side's stop and start characters are ^S and ^Q.

-c

Disables the reading of the user's .telnetrc file. (See telnet for the skiprc argument of the toggle telnet command.)

-d

Enable debugging by setting the initial value of the debug toggle to TRUE.

-E

Disable the telnet escape character.

-e escape_char

Set the initial telnet escape character to escape_char (default is Ctrl-]). This character lets you switch to rtelnet's command mode.

-L

Specifies an 8-bit data path on output. This causes the BINARY option to be negotiated on output.

-N

Numeric host address. Prevents look up of a symbolic name when the destination host is given as an IP address.

-n tracefile

Record trace information in the specified file.

-p policy

Use the IPsec policy specification string policy for the connections. For details of IPsec policy control, see the Library Reference.

-S tos

Sets the IP type-of-service (TOS) option for the telnet connection to the value tos, which can be a numeric TOS value or, on systems that support it, a symbolic TOS name found in the /etc/iptos file.

host

The official name, an alias, or the Internet address of a remote host.

port

A port number (address of an application). If a number isn't specified, the default telnet port is used.

Description:

The rftp and rtelnet utilities provide the well-known functionalities to hosts within a firewall. Normally, when a firewall is constructed, IP-accessibility across the firewall is cut off to reduce security risk to hosts within the firewall. As a result, inside hosts can no longer use many of the well-known tools directly to access the resources outside the firewall.

For further information on all rtelnet functionalities, please refer to telnet documentation.

These utilities restore the convenience of the well-known tools while maintaining the security requirement. Though the utilities differ very much from their counterparts in the use of the communication scheme, they should behave almost indistinguishably to the users.

These are "versatile" clients -- they can be used for connections to inside hosts directly and to outside hosts via SOCKS proxy servers. So they can be used as replacements of their traditional counterparts.

When rtelnet starts, it prints to stderr its version number and the name or IP address of its default SOCKS proxy server. It then consults the configuration file (/etc/socks.conf) to determine whether a request should be allowed or denied based on the requesting user, the destination host, and the requested service.

For allowable requests, the configuration file also dictates whether direct or proxy connection should be used to the given destination, and optionally the actual SOCKS servers to use for the proxy connection. See /etc/socks.conf.

You can use the environment variable SOCKS_NS to set the nameserver for domain name resolutions. Be sure you use the IP address of the nameserver you want to use, not its domain name. If SOCKS_NS doesn't exist, the IP address defined by the symbol SOCKS_DEFAULT_NS at compile time is used if the programs were compiled with that symbol defined. Otherwise, the nameservers specified in /etc/resolv.conf are used.

All the client processes log their activities using syslog() with facility daemon and level notice. In order to capture the log messages, you need to have syslogd running.

Files:

The rtelnet utility requires the libsocket.so shared library.

Environment variables:

SOCKS_SERVER

If defined, specifies the name or IP address of the SOCKS proxy server host to use, overriding the default server compiled into the programs.

SOCKS_NS

If defined, specifies the IP address of the domain nameserver that should be used for name resolution, overriding both the definition of symbol SOCKS_DEFAULT_NS and the file /etc/resolv.conf.

See also:

rftp, syslogd, telnet

syslog() in the Library Reference