tcp_scan.1

在网络中,有时候会想检查自己电脑的端口的状态,这是端口扫描器的C语言源代码,

.TH TCP_SCAN 1
.SH NAME
tcp_scan, udp_scan \- internet port scanners
.SH SYNOPSIS
.B tcp_scan
[options] host service(s)...
.sp
.B udp_scan
[options] host service(s)...
.SH DESCRIPTION
These commands take a list of internet services and investigate which
services are available from a given host.  The \fItcp_scan\fR command
looks for connection-oriented services; \fIudp_scan\fR identifies
active datagram ports.
.sp
Each \fIservice\fR argument may be specified as a symbolic name
(telnet), a port number (23), an interval (1-1023, telnet-smtp) or an
interval with the lower or upper bounds missing (the default bounds are
1 and 65535, respectively).
.sp
Options:
.IP -a
Report status of all specified services.
.IP "-b (tcp_scan only)"
Report banner information. Banners are converted to printable form
using C-like escape sequences. Whenever \fItcp_scan\fR finds that the
server does telnet options negotiation it sets the 't' flag in the
output.  This is useful to detect telnet servers on non-standard ports.
.IP "-l load"
Minimize the impact of network roundtrip delays by performing
\fIload\fR network probes in parallel. The default load is the
per-process open-file limit - 10.
.IP "-p port (udp_scan only)"
Use this port to verify that the host or network is alive. By default
the UDP port scanner uses port number 1. Specify a port number that is
known to be unreachable or inactive.
.IP "-s string (tcp_scan only)"
After a connection has been established, send
.I string
to the server. The following backslash escapes can be used:  \\ooo
(octal character code), \\b (backspace), \\f (formfeed), \\n (newline),
\\r (carriage-return), \\s (space), and \\t (horizontal tab). The
.I string
should be enclosed between quotes if it contains shell meta characters.
.IP "-S source_port"
Use the specified source port, instead of an arbitrary one.
Examples: "tcp_scan -S ftp-data", or "udp_scan -S domain".
.IP "-t time (tcp_scan only)"
Give up when the program has not found out anything within
.I time
seconds. This bounds the time lost when scanning systems with broken
TCP/IP implementations that do not send RESETs when contacted at a dead
port.  The udp scanner already has a built-in mechanism to detect dead
hosts.
.IP -u
Report probes that fail with "Host unreachable". Use this with packet
filters that pass most traffic.
.IP -U
Report probes that do \fInot\fR fail with "Host unreachable". Use this
with packet filters that block most traffic.
.IP "-w time (tcp_scan only)"
Wait for at most \fItime\fR seconds for banner information.
.SH WARNING
These programs will raise lots of alarms on sites that run the \fItcp
wrapper\fR or other network logging software. Use only with prior
permission.
.SH BUGS
The UDP port scanner relies on ICMP replies to detect that a service is
unavailable, and may report false positives when the host or network
dies in the middle of a measurement.
.PP
The TCP port scanner does not keep track of roundtrip times or
of retransmissions, and may overload hosts or networks.
.PP
With some UNIX implementations, a single "Host unreachable" condition
affects all connections that are being established with that host.
.PP
With some UNIX implementations, a single "Host unreachable" condition
affects all TCP connections to that host, even those that already
exist.
.SH AUTHOR
Wietse Venema