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scanssh(1) [debian man page]

scanssh(1)						    BSD General Commands Manual 						scanssh(1)

scanssh -- scans the Internet for open proxies and SSH servers SYNOPSIS
scanssh [-VIERph] [-s scanners,...] [-n ports,...] [-e excludefile] addresses... DESCRIPTION
ScanSSH scans the given addresses and networks for running services. It mainly allows the detection of open proxies and Internet services. For known services, ScanSSH will query their version number and displays the results in a list. The adresses can be either specified as an IPv4 address or an CIDR like IP prefix, ipaddress/masklength. Ports can be appended by adding a colon at the end of address specification. Additionally, the following two commands can be prefixed to the address: random(n[,seed])/ The random command selects random address from the address range specified. The arguments are as follows: n is the number of address to randomly create in the given network and seed is a seed for the pseudo random number generator. split(s,e)/ The split command is used to split the address range in several unique components. This can be use to scan from serveral hosts in parallel. The arguments are as follows: e specifies the number of hosts scanning in parallel and s is the number of the host this particular scan runs on. The options are as follows: -V Causes scanssh to print its version number. -I Does not send a SSH identification string. -E Exit the program, if the file containing the addresses for exclusion can not be found. -R If addresses are generated at random, this flag causes the program to ignore excluded addresses from the exclude file. The default behaviour is to always exclude addresses. -p Specifies that ScanSSH should operate as a proxy detector. This flag sets the default modes and default scanners to detect open proxies. -h Displays the usage of the program. -n ports,... Specifies the port numbers to scan. Ports are separated by commas. Each specified scanner is run for each port in this list. The default is 22. -s scanners Specifies a number of scanners should be executed for each open port. Multiple scanners are separated by commas. The fol- lowing scanners are currently supported: ssh Finds versions for SSH, Web and SMTP servers. socks5 Detects if a SOCKS V5 proxy is running on the port. socks4 Detects if a SOCKS V4 proxy is running on the port. http-proxy Detects a HTTP get proxy. http-connect Detects a HTTP connect proxy. telnet-proxy Detects telnet based proxy servers. -e excludefile Specifies the file that contains the addresses to be excluded from the scan. The syntax is the same as for the addresses on the command line. The output from scanssh contains only IP addresses. However, the IP addresses can be converted to names with the logresolve(8) tool included in the Apache webserver. EXAMPLES
The following command scans the class C network - for open proxies: scanssh -p The next command scans for ssh servers on port 22 only: scanssh -n 22 -s ssh The following command can be used in a parallel scan. Two hosts scan the specified networks randomly, where this is the first host: scanssh 'random(0,rsd)/split(1,2)/(,80' BUGS
At the moment, scanssh leaves a one line entry in the log file of the ssh server. It is probably not possible to avoid that. BSD
July 17, 2000 BSD

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NC(1)							    BSD General Commands Manual 						     NC(1)

nc -- arbitrary TCP and UDP connections and listens SYNOPSIS
nc [-46DdhklnrStUuvzC] [-i interval] [-P proxy_username] [-p source_port] [-s source_ip_address] [-T ToS] [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]] [hostname] [port[s]] DESCRIPTION
The nc (or netcat) utility is used for just about anything under the sun involving TCP or UDP. It can open TCP connections, send UDP pack- ets, listen on arbitrary TCP and UDP ports, do port scanning, and deal with both IPv4 and IPv6. Unlike telnet(1), nc scripts nicely, and separates error messages onto standard error instead of sending them to standard output, as telnet(1) does with some. Common uses include: o simple TCP proxies o shell-script based HTTP clients and servers o network daemon testing o a SOCKS or HTTP ProxyCommand for ssh(1) o and much, much more The options are as follows: -4 Forces nc to use IPv4 addresses only. -6 Forces nc to use IPv6 addresses only. -D Enable debugging on the socket. -d Do not attempt to read from stdin. -h Prints out nc help. -i interval Specifies a delay time interval between lines of text sent and received. Also causes a delay time between connections to multiple ports. -k Forces nc to stay listening for another connection after its current connection is completed. It is an error to use this option without the -l option. -l Used to specify that nc should listen for an incoming connection rather than initiate a connection to a remote host. It is an error to use this option in conjunction with the -p, -s, or -z options. Additionally, any timeouts specified with the -w option are ignored. -n Do not do any DNS or service lookups on any specified addresses, hostnames or ports. -P proxy_username Specifies a username to present to a proxy server that requires authentication. If no username is specified then authentication will not be attempted. Proxy authentication is only supported for HTTP CONNECT proxies at present. -p source_port Specifies the source port nc should use, subject to privilege restrictions and availability. It is an error to use this option in conjunction with the -l option. -q after EOF on stdin, wait the specified number of seconds and then quit. If seconds is negative, wait forever. -r Specifies that source and/or destination ports should be chosen randomly instead of sequentially within a range or in the order that the system assigns them. -S Enables the RFC 2385 TCP MD5 signature option. -s source_ip_address Specifies the IP of the interface which is used to send the packets. It is an error to use this option in conjunction with the -l option. -T ToS Specifies IP Type of Service (ToS) for the connection. Valid values are the tokens ``lowdelay'', ``throughput'', ``reliability'', or an 8-bit hexadecimal value preceded by ``0x''. -C Send CRLF as line-ending -t Causes nc to send RFC 854 DON'T and WON'T responses to RFC 854 DO and WILL requests. This makes it possible to use nc to script tel- net sessions. -U Specifies to use Unix Domain Sockets. -u Use UDP instead of the default option of TCP. -v Have nc give more verbose output. -w timeout If a connection and stdin are idle for more than timeout seconds, then the connection is silently closed. The -w flag has no effect on the -l option, i.e. nc will listen forever for a connection, with or without the -w flag. The default is no timeout. -X proxy_protocol Requests that nc should use the specified protocol when talking to the proxy server. Supported protocols are ``4'' (SOCKS v.4), ``5'' (SOCKS v.5) and ``connect'' (HTTPS proxy). If the protocol is not specified, SOCKS version 5 is used. -x proxy_address[:port] Requests that nc should connect to hostname using a proxy at proxy_address and port. If port is not specified, the well-known port for the proxy protocol is used (1080 for SOCKS, 3128 for HTTPS). -z Specifies that nc should just scan for listening daemons, without sending any data to them. It is an error to use this option in conjunction with the -l option. hostname can be a numerical IP address or a symbolic hostname (unless the -n option is given). In general, a hostname must be specified, unless the -l option is given (in which case the local host is used). port[s] can be single integers or ranges. Ranges are in the form nn-mm. In general, a destination port must be specified, unless the -U option is given (in which case a socket must be specified). CLIENT
/SERVER MODEL It is quite simple to build a very basic client/server model using nc. On one console, start nc listening on a specific port for a connec- tion. For example: $ nc -l 1234 nc is now listening on port 1234 for a connection. On a second console (or a second machine), connect to the machine and port being listened on: $ nc 1234 There should now be a connection between the ports. Anything typed at the second console will be concatenated to the first, and vice-versa. After the connection has been set up, nc does not really care which side is being used as a 'server' and which side is being used as a 'client'. The connection may be terminated using an EOF ('^D'). DATA TRANSFER
The example in the previous section can be expanded to build a basic data transfer model. Any information input into one end of the connec- tion will be output to the other end, and input and output can be easily captured in order to emulate file transfer. Start by using nc to listen on a specific port, with output captured into a file: $ nc -l 1234 > filename.out Using a second machine, connect to the listening nc process, feeding it the file which is to be transferred: $ nc 1234 < After the file has been transferred, the connection will close automatically. TALKING TO SERVERS
It is sometimes useful to talk to servers ``by hand'' rather than through a user interface. It can aid in troubleshooting, when it might be necessary to verify what data a server is sending in response to commands issued by the client. For example, to retrieve the home page of a web site: $ echo -n "GET / HTTP/1.0 " | nc 80 Note that this also displays the headers sent by the web server. They can be filtered, using a tool such as sed(1), if necessary. More complicated examples can be built up when the user knows the format of requests required by the server. As another example, an email may be submitted to an SMTP server using: $ nc [-C] localhost 25 << EOF HELO MAIL FROM:<> RCPT TO:<> DATA Body of email. . QUIT EOF PORT SCANNING
It may be useful to know which ports are open and running services on a target machine. The -z flag can be used to tell nc to report open ports, rather than initiate a connection. For example: $ nc -z 20-30 Connection to 22 port [tcp/ssh] succeeded! Connection to 25 port [tcp/smtp] succeeded! The port range was specified to limit the search to ports 20 - 30. Alternatively, it might be useful to know which server software is running, and which versions. This information is often contained within the greeting banners. In order to retrieve these, it is necessary to first make a connection, and then break the connection when the banner has been retrieved. This can be accomplished by specifying a small timeout with the -w flag, or perhaps by issuing a "QUIT" command to the server: $ echo "QUIT" | nc 20-30 SSH-1.99-OpenSSH_3.6.1p2 Protocol mismatch. 220 IMS SMTP Receiver Version 0.84 Ready EXAMPLES
Open a TCP connection to port 42 of, using port 31337 as the source port, with a timeout of 5 seconds: $ nc -p 31337 -w 5 42 Open a UDP connection to port 53 of $ nc -u 53 Open a TCP connection to port 42 of using as the IP for the local end of the connection: $ nc -s 42 Create and listen on a Unix Domain Socket: $ nc -lU /var/tmp/dsocket Connect to port 42 of via an HTTP proxy at, port 8080. This example could also be used by ssh(1); see the ProxyCommand directive in ssh_config(5) for more information. $ nc -x10.2.3.4:8080 -Xconnect 42 The same example again, this time enabling proxy authentication with username ``ruser'' if the proxy requires it: $ nc -x10.2.3.4:8080 -Xconnect -Pruser 42 SEE ALSO
cat(1), ssh(1) AUTHORS
Original implementation by *Hobbit* <>. Rewritten with IPv6 support by Eric Jackson <>. CAVEATS
UDP port scans will always succeed (i.e. report the port as open), rendering the -uz combination of flags relatively useless. BSD
May 31, 2007 BSD

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