Re: World writable Permission Needed or Not

On 2008-02-21, Debu <debasish4@xxxxxxxxx> wrote:
Hi,

Let me explain the exact problem. I have connected two boxes
running SVR4 Unix through serial ports via a NULL modem cable. Two
ordinary/Normal users are siting on both end using "/dev/console" not
any Pseudo terminals. I can communicate in between them using "/usr/
bin/cu -l /dev/term/01" which works via "/usr/sbin/cs" daemon.

One interesting thing here is after connection establishment i can
write on both end; even if i remove world writable from "/dev/term/
01". How this thing is possible if no write permission is there on the
serial device????????

Either /usr/sbin/cs runs as root, or /usr/bin/cu has setuid permission.
I'm on an Ubuntu Linux system, so things might work differently here
(there is no /usr/sbin/cs here, also cu and uucp are not installed by
default). In Linux, access to serial ports and other devices is usually
controlled by group permissions.

wheather i need world writable for serial devices or not if i will
connect to some modem through serial communication??????

If you use cu with a modem, you may need to edit the configuration files
in /etc/uucp. Depending what you are doing, you might set up (m)getty
to provide a login prompt on the called system's serial port. Or you
might use ppp.
.

Relevant Pages

  • Serial port modem connection
    ... I have a GPRS modem that I want to use for internet connectivity on my ... My CE Platform has 3 serial ports - and I have first-third instance of ... connection, only COM1 and COM3 are available but if I get the available ... I create the additional modem connection in the registry as follows: ...
    (microsoft.public.windowsce.platbuilder)
  • RE: Installing PCI modem in machine with 4 serial ports (HELP!)
    ... serial ports) and it is found as sio4 and works perfectly. ... > say the modem works, you failed to say if it worked in an FBSD ... > and since many cheap serial cards do not fully decode the 16-bit IO ...
    (freebsd-questions)
  • Re: Cant Query External Serial Modem
    ... so no serial ports there.) ... If you are able to get an internet connection through your iMac modem, ... ports to share its connection among your laptops and/or your Ubuntu PC ...
    (Ubuntu)
  • Windows XPe/Modem with PPP does not detect lost connection
    ... We have connected a GPRS Modem to one of the serial ports and use it for Remote ... the connector on one side) the XPe operating system does not detect the hangup of the connection. ... conclude that there might be something wrong with the serial drivers not ...
    (comp.arch.embedded)
  • Re: Does hardware modem need driver for Linux?
    ... still buy PCI cards with 2 such serial ports if needed, ... the driver. ... /bin/setserial command to tell the kernel where the modem is hiding. ... May not be included on your Live CD, but see if you can find the HOWTOs ...
    (comp.os.linux.hardware)