[ale] Need help reading tcpdump output

[Jim Philips]

Could you post the output of ifconfig? That might show us all something
that didn't come up in the tcpdump.


On Fri, 2002-02-15 at 06:37, Gary MacKay wrote:
> I do not have a ppp0 interface on either firewall. There are two nic's
> in each and they are all set to MTU of 1500.
> 
> 
> Jim Philips wrote:
> > 
> > Try running an ifconfig on your ppp0 interface with the cable modem and
> > with DSL. You may find that MTU is different depending on the device you
> > use to connect. I had major connection problenms with DSL a few weeks
> > ago. They all went away when I reduced MTU to 1474 from 1492.
> > 
> > On Thu, 2002-02-14 at 19:51, Gary MacKay wrote:
> > > I have a cable modem and a DSL line in my office. I use the cable modem
> > > to serve 'net access to my internal network and the DSL only has my
> > > email/web server on it. I am having problems sending email to a few
> > > domains, not all, just a few. I found I can telnet to port 25 of one of
> > > the failing domains via my cable modem, but not via the DSL line. Below
> > > are the first packett trace of each. The only thing I can see different
> > > is the flags SWE instead of just S. I do not know enough about the flags
> > > to know what that means nor how to fix it. The address I'm trying to
> > > send email to is 170.206.225.44.
> > >
> > > --------DSL Line: fails
> > > 19:32:35.162544 207.87.222.229.15255 > 170.206.225.44.25: SWE
> > > 3747157433:3747157433(0) win 5840 <mss 1460,sackOK,timestamp 303797345
> > > 0,nop,wscale 0> (DF) [tos 0x10]
> > >
> > > --------Cable modem: works
> > > 15:39:37.774455 11.22.33.44.41159 > 170.206.225.44.25: S
> > > 3934758720:3934758720(0) win 5840 <mss 1460,sackOK,timestamp 329647437
> > > 0,nop,wscale 0> (DF) [tos 0x10]
> > >
> > > Both lines have a firewall with the exact same firewall rules, except
> > > for ports 25 and 110 on the DSL line. What am I missing?
> > >
> > > - Gary
> > >
> > > ---
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> > >
> > 
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sent to listmaster at ale dot org.