My regular (Debian) server has a serial connection to an external processor. The server's ppp daemon is started for an IP connection as shown below. It is used for tftp, mounting a remote drive, ssh, etc.

/usr/sbin/pppd ttyS0 115200 lock -detach local passive persist noauth allow-ip 192.168.4.2 192.168.4.1:192.168.4.2 &

I want to set up a laptop as a mobile "server" occasionally to communicate to the same device but being a late model laptop it has no serial port. Is attaching one of the USB-to-serial adapters a transparent way to accomplish this? In other words, would the ppp daemon start the same way as above or do I have to do more complicated things to deal with the USB?

Thanks,
Ron

Yes, assuming your usb serial port adapter is recognized the device ID will be /dev/ttyUSB0

I had to drop this issue some months ago, but am now back to trying to solve it.

I tried the same command to start the ppp daemon using the /dev/ttyUSB0, but no luck. I get the error msg

LCP: timeout sending Config-Requests

and pinging the subordinate address gets no answer. Are any of the command options I'm using inappropriate for USB-as-serial?

Thanks,
Ron

Does /dev/ttyUSB0 exist?
Post the output of the command:
lsusb

Yes, it exists:

crw-rw---- 1 root dialout 188, 0 2010-12-20 15:13 /dev/ttyUSB0

'lsusb' results:
Bus 002 Device 006: ID 1a86:7523 Unknown HL-340 USB-Serial adapter
Bus 002 Device 004: ID 0461:4d81 Primax Electronics, Ltd
Bus 002 Device 003: ID 413c:2101 Dell Computer Corp. SmartCard Reader Keyboard
Bus 002 Device 002: ID 8087:0020
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:0020
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Hmmm. So I need to identify the adapter? I think I picked it up at BestBuy or Office Depot & didn't keep any specs on it, if there were any. I saw a mention of using the insmod command with vendor & product identifiers as I've been googling around, but was hoping not to have to do that. Shucks -- what happened to universality? :-)

Ron

Ooh -- never mind. I had been using a null modem adapter for the serial connection on the old system & still had that between the serial line & the USB-to-serial adapter. That was probably causing the problem with the system unable to ID the adapter. When I took that out of the picture things work fine.

Thanks so much for your help anyway.

Ron