Discussion:
PPP over standard serial port
(too old to reply)
Elison
2011-06-21 13:53:27 UTC
Permalink
Hi,

I am trying to establish a ppp link over standard serial port. I have
2 computers running Linux. I have connected a standard serial cable
between them.
I have tested the serial connection using cutecom/minicom on both the
machines.

Searching a bit on the internet led me to :
All you need to do now is to start pppd on both systems. So, on both
machines execute the command:-
pppd -detach crtscts lock <local IP>:<remote IP> /dev/ttyS0 38400 &

So on PC 1, I issued:
pppd -detach crtscts lock 192.168.20.2:192.168.20.3 /dev/ttyS0 38400 &
and on PC 2, I issued:
pppd -detach crtscts lock 192.168.20.3:192.168.20.2 /dev/ttyS0 38400 &

But tail /var/log/messages gives me timeout sending lcp-config-
requests.

I also tried creating /etc/ppp/options.ttyS0 on both machines.
Machine 1:
local
lock
38400
192.168.20.2:192.168.20.3
debug
noauth
nodeflate
nobsdcomp

Machine 2:
local
lock
38400
192.168.20.3:192.168.20.2
debug
noauth
nodeflate
nobsdcomp

But still no luck after executing 'pppd file /etc/ppp/options.ttyS0'.

How do I establish a ppp connection between these 2 computers over the
serial port?

OS 1: Fedora 13, 32 bit
OS 2: Fedora 14, 32 bit

Thanks and Regards,
Elison
Moe Trin
2011-06-21 19:46:54 UTC
Permalink
On Tue, 21 Jun 2011, in the Usenet newsgroup comp.protocols.ppp, in article
<8a93c397-32b4-4aef-9b05-***@h38g2000pro.googlegroups.com>, Elison
wrote:

NOTE: Posting from groups.google.com (or some web-forums) dramatically
reduces the chance of your post being seen. Find a real news server.
Post by Elison
I am trying to establish a ppp link over standard serial port. I have
2 computers running Linux. I have connected a standard serial cable
between them.
"a standard serial cable" meaning what exactly? What is needed here is
called a cross-over or "null modem" cable rather than one wired
pin-to-pin. If you're not familiar with this, see the Serial-HOWTO

278767 Feb 10 15:21 Serial-HOWTO
Post by Elison
I have tested the serial connection using cutecom/minicom on both
the machines.
And can machine "A" talk to machine "B" using minicom?
Post by Elison
All you need to do now is to start pppd on both systems. So, on both
machines execute the command:-
pppd -detach crtscts lock <local IP>:<remote IP> /dev/ttyS0 38400 &
Kind of old, and less helpful, but

23129 Jul 20 2001 Serial-Laplink-HOWTO
Post by Elison
But tail /var/log/messages gives me timeout sending lcp-config-
requests.
Do you see anything from the "other" system in the log? This is what
a (dialin) connection start should look like:

===================
Jul 3 09:55:27 gtech pppd[924]: sent [LCP ConfReq id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]
Jul 3 09:55:27 gtech pppd[924]: rcvd [LCP ConfReq id=0x1 < 00 04 00
00> <mru 1524> <asyncmap 0xa0000> <auth pap> <pcomp> <accomp> < 11 04
05 f4> < 13 09 03 00 c0 7b 90 17 04>]

Here, this box said hello before hearing from the peer. The peer
wants to have this system authenticate with PAP ( <auth pap> ), and is
offering three services this box never heard of.

Jul 3 09:55:27 gtech pppd[924]: sent [LCP ConfRej id=0x1 < 00 04 00
00> < 11 04 05 f4> < 13 09 03 00 c0 7b 90 17 04>]

So, this box rejects the unknown stuff.

Jul 3 09:55:27 gtech pppd[924]: rcvd [LCP ConfAck id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]
Jul 3 09:55:27 gtech pppd[924]: rcvd [LCP ConfReq id=0x2 <mru 1524>
<asyncmap 0xa0000> <auth pap> <pcomp> <accomp>]
Jul 3 09:55:27 gtech pppd[924]: sent [LCP ConfAck id=0x2 <mru 1524>
<asyncmap 0xa0000> <auth pap> <pcomp> <accomp>]

The peer comes back and acknowledges the original 'hello', and says hello
itself, but this time without the unknown services. This box acknowledges
the peer.

Jul 3 09:55:27 gtech pppd[924]: sent [PAP AuthReq id=0x1 user=<hidden>
password=<hidden>]
Jul 3 09:55:28 gtech pppd[924]: rcvd [PAP AuthAck id=0x1 ""]

This box sends in the username and password (here edited out), and the peer
comes back and approves the login.

Jul 3 09:55:28 gtech pppd[924]: sent [IPCP ConfReq id=0x1 <addr
0.0.0.0> <compress VJ 0f 01>]
Jul 3 09:55:30 gtech pppd[924]: sent [CCP ConfReq id=0x1 <deflate 15>
<deflate(old#) 15> <bsd v1 15>]

This box now asks to talk TCP/IP, but doesn't know it's address (normal),
and suggests two ways to compress data.

Jul 3 09:55:30 gtech pppd[924]: rcvd [IPCP ConfReq id=0x1 <compress
VJ 0f 01> <addr 201.48.5.2>]
Jul 3 09:55:30 gtech pppd[924]: sent [IPCP ConfAck id=0x1 <compress
VJ 0f 01> <addr 201.48.5.2>]

The peer comes back and asks to talk TCP/IP, and wants to use that address.
This box approves this.

Jul 3 09:55:30 gtech pppd[924]: rcvd [IPCP ConfNak id=0x1 <addr
201.48.5.158>]
Jul 3 09:55:30 gtech pppd[924]: sent [IPCP ConfReq id=0x2 <addr
201.48.5.158> <compress VJ 0f 01>]

The peer comes back and says that you can't use address 0.0.0.0, and
suggests asking to use this address. This peer does so.

Jul 3 09:55:30 gtech pppd[924]: rcvd [IPCP ConfAck id=0x2 <addr
201.48.5.158> <compress VJ 0f 01>]
Jul 3 09:55:30 gtech pppd[924]: local IP address 201.48.5.158
Jul 3 09:55:30 gtech pppd[924]: remote IP address 201.48.5.2

The peer approves our use of this address, and the ppp link is now up
and running.

===================

Now, do you see the boxes talking back and forth - or only one box
sending the same thing over and over:

Jul 3 09:55:24 gtech pppd[924]: sent [LCP ConfReq id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]

with the "id=0x1" value incrementing? That's likely to be a wiring
problem, but check the logs on BOTH systems.
Post by Elison
I also tried creating /etc/ppp/options.ttyS0 on both machines.
Try '/etc/ppp/options'
Post by Elison
local
lock
38400
192.168.20.2:192.168.20.3
debug
OK - but make sure your syslog daemon is putting 'daemon.debug' level
messages in some file you can read.
Post by Elison
noauth
nodeflate
nobsdcomp
Not needed.

Old guy
Elison
2011-06-22 06:16:16 UTC
Permalink
Post by Moe Trin
On Tue, 21 Jun 2011, in the Usenet newsgroup comp.protocols.ppp, in article
NOTE: Posting from groups.google.com (or some web-forums) dramatically
reduces the chance of your post being seen.  Find a real news server.
Post by Elison
I am trying to establish a ppp link over standard serial port. I have
2 computers running Linux. I have connected a standard serial cable
between them.
"a standard serial cable" meaning what exactly?  What is needed here is
called a cross-over or "null modem" cable rather than one wired
pin-to-pin.  If you're not familiar with this, see the Serial-HOWTO
        278767 Feb 10 15:21 Serial-HOWTO
Post by Elison
I have tested the serial connection using cutecom/minicom on both
the machines.
And can machine "A" talk to machine "B" using minicom?
Post by Elison
All you need to do now is to start pppd on both systems. So, on both
machines execute the command:-
pppd -detach crtscts lock <local IP>:<remote IP> /dev/ttyS0 38400 &
Kind of old, and less helpful, but
         23129 Jul 20  2001 Serial-Laplink-HOWTO
Post by Elison
But tail /var/log/messages gives me timeout sending lcp-config-
requests.
Do you see anything from the "other" system in the log?   This is what
===================
Jul  3 09:55:27 gtech pppd[924]: sent [LCP ConfReq id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]
Jul  3 09:55:27 gtech pppd[924]: rcvd [LCP ConfReq id=0x1 < 00 04 00
00> <mru 1524> <asyncmap 0xa0000> <auth pap> <pcomp> <accomp> < 11 04
05 f4> < 13 09 03 00 c0 7b 90 17 04>]
Here, this box said hello before hearing from the peer. The peer
wants to have this system authenticate with PAP ( <auth pap> ), and is  
offering three services this box never heard of.
Jul  3 09:55:27 gtech pppd[924]: sent [LCP ConfRej id=0x1 < 00 04 00
00> < 11 04 05 f4> < 13 09 03 00 c0 7b 90 17 04>]
So, this box rejects the unknown stuff.
Jul  3 09:55:27 gtech pppd[924]: rcvd [LCP ConfAck id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]
Jul  3 09:55:27 gtech pppd[924]: rcvd [LCP ConfReq id=0x2 <mru 1524>
<asyncmap 0xa0000> <auth pap> <pcomp> <accomp>]
Jul  3 09:55:27 gtech pppd[924]: sent [LCP ConfAck id=0x2 <mru 1524>
<asyncmap 0xa0000> <auth pap> <pcomp> <accomp>]
The peer comes back and acknowledges the original 'hello', and says hello
itself, but this time without the unknown services. This box acknowledges
the peer.
Jul  3 09:55:27 gtech pppd[924]: sent [PAP AuthReq id=0x1 user=<hidden>
password=<hidden>]
Jul  3 09:55:28 gtech pppd[924]: rcvd [PAP AuthAck id=0x1 ""]
This box sends in the username and password (here edited out), and the peer
comes back and approves the login.
Jul  3 09:55:28 gtech pppd[924]: sent [IPCP ConfReq id=0x1 <addr
0.0.0.0> <compress VJ 0f 01>]
Jul  3 09:55:30 gtech pppd[924]: sent [CCP ConfReq id=0x1 <deflate 15>
<deflate(old#) 15> <bsd v1 15>]
This box now asks to talk TCP/IP, but doesn't know it's address (normal),
and suggests two ways to compress data.  
Jul  3 09:55:30 gtech pppd[924]: rcvd [IPCP ConfReq id=0x1 <compress
VJ 0f 01> <addr 201.48.5.2>]
Jul  3 09:55:30 gtech pppd[924]: sent [IPCP ConfAck id=0x1 <compress
VJ 0f 01> <addr 201.48.5.2>]
The peer comes back and asks to talk TCP/IP, and wants to use that address.
This box approves this.
Jul  3 09:55:30 gtech pppd[924]: rcvd [IPCP ConfNak id=0x1 <addr
201.48.5.158>]
Jul  3 09:55:30 gtech pppd[924]: sent [IPCP ConfReq id=0x2 <addr
201.48.5.158> <compress VJ 0f 01>]
The peer comes back and says that you can't use address 0.0.0.0, and
suggests asking to use this address. This peer does so.
Jul  3 09:55:30 gtech pppd[924]: rcvd [IPCP ConfAck id=0x2 <addr
201.48.5.158> <compress VJ 0f 01>]
Jul  3 09:55:30 gtech pppd[924]: local  IP address 201.48.5.158
Jul  3 09:55:30 gtech pppd[924]: remote IP address 201.48.5.2
The peer approves our use of this address, and the ppp link is now up
and running.
===================
Now, do you see the boxes talking back and forth - or only one box
Jul  3 09:55:24 gtech pppd[924]: sent [LCP ConfReq id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]
with the "id=0x1" value incrementing?   That's likely to be a wiring
problem, but check the logs on BOTH systems.
Post by Elison
I also tried creating /etc/ppp/options.ttyS0 on both machines.
Try '/etc/ppp/options'
Post by Elison
local
lock
38400
192.168.20.2:192.168.20.3
debug
OK - but make sure your syslog daemon is putting 'daemon.debug' level
messages in some file you can read.
Post by Elison
noauth
nodeflate
nobsdcomp
Not needed.
        Old guy
Hi,
Thanks for the reply.

I am using a standard serial cable, not crossover.
Both machines can talk to each other using minicom so I am "assuming"
ppp should work.
The debug does not show any LCP packets sent or recieved debug.
tail /var/log/messages is same on both the machines.

I guess I have to check with a crossover cable.

Thanks,
Elison
x***@gmail.com
2017-11-20 02:54:31 UTC
Permalink
I try to run：
pppd proxyarp mtu 1280 persist nodeflate noauth lcp-echo-interval 10
crtscts lock 10.10.1.2:10.10.1.1 /dev/ttyS4 115200 debug nodetach

in my system，and it sending the same thing over and over：

sent [LCP ConfReq id=0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]

How can I check the problem

Thank you！
Moe Trin
2017-11-20 21:15:08 UTC
Permalink
On Sun, 19 Nov 2017, in the Usenet newsgroup comp.protocols.ppp, in article
<fa1ebc1a-2d3e-451a-b474-***@googlegroups.com>,
***@gmail.com wrote:

NOTE: Posting from groups.google.com (or some web-forums) dramatically
reduces the chance of your post being seen. Find a real news server.
Post by x***@gmail.com
I try to run
pppd proxyarp mtu 1280 persist nodeflate noauth lcp-echo-interval 10
crtscts lock 10.10.1.2:10.10.1.1 /dev/ttyS4 115200 debug nodetach
in my system
What are you trying to do? Connect to an ISP? Connect a serial
link to another computer? What operating system? You show
"/dev/ttyS4" which in Linux would be the fifth (very uncommon) classic
RS-232 serial port. Assuming Linux, what does 'ls' show?

[spica ~]$ ls /dev/ttyS*
/dev/ttyS0 /dev/ttyS1 /dev/ttyS2 /dev/ttyS3
[spica ~]$

During boot, is your kernel loading an appropriate serial driver?
In /var/log/dmesg, I see

[ 0.518034] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 0.538368] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

Notice the second line - on this computer, there is an actual RS-232
serial port. On two other computers here, the line is missing
because there is no classic serial port (everything is USB, which is
a different device and driver).
Post by x***@gmail.com
and it sending the same thing over and over
sent [LCP ConfReq id=3D0x1 <asyncmap
0x0> <magic 0x8bab12d4> <pcomp> <accomp>]
"Hello! Is anyone out there?"

The peer at the other end of the serial link is not responding.
Is your connection to the peer (modem, cross-over cable or similar)
connected? Is there a pppd daemon listening on the appropriate port
on the peer? More details needed.

Old guy

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