Puede reproducir esto configurando el reenvío de puerto dinámico SSH:
man ssh:
-D [bind_address:]port
Specifies a local “dynamic” application-level port forwarding. This works by allocating a socket
to listen to port on the local side, optionally bound to the specified bind_address. Whenever a
connection is made to this port, the connection is forwarded over the secure channel, and the
application protocol is then used to determine where to connect to from the remote machine. Cur‐
rently the SOCKS4 and SOCKS5 protocols are supported, and ssh will act as a SOCKS server. Only
root can forward privileged ports. Dynamic port forwardings can also be specified in the configu‐
ration file.
IPv6 addresses can be specified by enclosing the address in square brackets. Only the superuser
can forward privileged ports. By default, the local port is bound in accordance with the
GatewayPorts setting. However, an explicit bind_address may be used to bind the connection to a
specific address. The bind_address of “localhost” indicates that the listening port be bound for
local use only, while an empty address or ‘*’ indicates that the port should be available from all
interfaces.
Inicie un proxy SOCKS en localhost, puerto 2302:
$ ssh -v -ND 2302 user@host
Para enrutar el tráfico HTTP a través de este túnel, en Firefox:
Editar -> Preferencias -> Avanzado -> pestaña Red -> Configuración -> Configuración manual del proxy -> Host SOCKS: localhost y Puerto: 2302
Para utilizar el proxy SOCKS con otro tráfico, puede usar un programa de socksifier como tsocks:
[I] net-proxy/tsocks
Available versions: 1.8_beta5-r3 ~1.8_beta5-r4 1.8_beta5-r5 ~1.8_beta5-r6 {tordns}
Installed versions: 1.8_beta5-r5(10:08:28 AM 06/15/2010)(-tordns)
Homepage: http://tsocks.sourceforge.net/
Description: Transparent SOCKS v4 proxying library
En mi Gentoo, edite lo /etc/socks/tsocks.confsiguiente:
# Otherwise we use the server
server = 127.0.0.1
server_port = 2302
Pruebas:
$ tsocks telnet 255.255.255.255 25
Verá algo como esto en el /var/log/secureservidor SSH:
sshd[28491]: error: connect_to 255.255.255.255 port 25: failed.
La parte que no entiendo es exactamente quién está tratando de conectarse a esas direcciones
Para restringir, eche un vistazo a /var/log/secure( auth.logen su distribución) y examine quién ha iniciado sesión antes de esto:
sshd[26898]: pam_unix(sshd:session): session opened for user quanta