comp.os.linux.networking

On Sat, 5 Apr 2008, in the Usenet newsgroup comp.os.linux.networking, in article
, Clifford Kite wrote:

>Moe Trin wrote:

>> Looking at the man page or the source file for ~/pppd/options.c there
>> is no '-mru' option. The Changes-2.3 file stated for 2.3.0
>
>Hi Moe!

Hi Clifford!

>Man pages don't always include dated options while the source may but
>not always where one would expect.

You caught me there - I knew the option was still included, as pppd
would be barfing otherwise. I thought that option was in ppps/options.c
with the rest of the mess. ;-)

>~/shop/pppd/ppp-2.4.4/pppd$ grep -Irs '\-mru' .
>./lcp.c: { "default-mru", o_bool, &lcp_wantoptions[0].neg_mru,
>./lcp.c: { "-mru", o_bool, &lcp_wantoptions[0].neg_mru,

Ah well - learn something new.

>./pppd.8:.B default\-mru

Now that's the man page... OK - it's the title of an option. The
section reads:

.B default\-mru
Disable MRU [Maximum Receive Unit] negotiation. With this option,
pppd will use the default MRU value of 1500 bytes for both the
transmit and receive direction.
.TP

which turns out to read:

default-mru
Disable MRU [Maximum Receive Unit] negotiation. With this
option, pppd will use the default MRU value of 1500 bytes
for both the transmit and receive direction.

when displayed with the man command.

>Unfortunately I have nothing else to offer the OP in the way of help. :(
>But I would be suspicious of the Java applet. Or the new Java versions
>of M$:

I thought of that, except he indicated he got it working by setting the
MRU up to 1500.

I guess I tracked it down to the packet size again. Except this time
I needed to add -mru to /etc/ppp/options to get it working. Which
sets the MRU to 1500.

Now what he _could_ be seeing is different versions on a pool of servers
with the same name. Wouldn't be the first time that has occurred. I also
didn't understand (or comment upon) this item in his original post:

I generally run the network at an MTU of 576. If I don't connect
with my ISP at that MTU, it generally dials out again about every two
minutes. Any idea why it works on the router and not any computers
connecting through it?

To the O/P - if this is still a problem, I suggest running a packet
sniffer, or at least putting a command in /etc/ppp/ip.up that reads

/bin/netstat -anptu > /tmp/ppp.traffic

which will run that command when the link comes up. You MAY need to
precede it with a five or ten second 'sleep' command. If you have
tcpdump installed, you could use

/usr/sbin/tcpdump -ni ppp0 -c 20 -w /tmp/ppp.tcpdump

which will put the first twenty packets over the ppp0 interface into
a packet dump file named '/tmp/ppp.tcpdump'

Old guy