[ale] Bellsouth to Speakeasy?

James P. Kinney III jkinney at localnetsolutions.com
Sat Jan 25 12:03:47 EST 2003


On Fri, 2003-01-24 at 23:45, John Wells wrote:
> Hmmm...not sure I agree.  Note I said "to other boxes' port 25'. If I
> simply telnetted to another box, it would be 23.
> 
> But, for instance:
> 
> telnet sourceillustrated.com 25
> 
> This is outbound traffic to another machine on port 25.
> 
> Here's the tcpdump:
> 
> # /usr/sbin/tcpdump -nn host sourceillustrated.com
> 
> tcpdump: listening on eth0
> 23:39:16.158858 172.16.2.8.32924 > 66.33.1.213.25: S
> 2277599437:2277599437(0) win 5840 <mss 1460,sackOK,timestamp 1925171
> 0,nop,wscale 0> (DF) [tos 0x10]
> 23:39:16.196884 66.33.1.213.25 > 172.16.2.8.32924: S
> 2470847785:2470847785(0) ack 2277599438 win 32476 <mss
> 1412,sackOK,timestamp 1738917213 1925171,nop,wscale 0> (DF)
> 23:39:16.196934 172.16.2.8.32924 > 66.33.1.213.25: . ack 1 win 5840
Note** the packets _leave_ your box on port 32924.

BS filters traffic outbound from your box on port 25. Theupstream router
is set to deny packets with a source port of 25 NOT going to
mail.bellsouth.net

> <nop,nop,timestamp 1925191 1738917213> (DF) [tos 0x10]
> 23:39:16.237111 66.33.1.213.25 > 172.16.2.8.32924: P 1:36(35) ack 1 win
> 32476 <nop,nop,timestamp 1738917217 1925191> (DF)
> 23:39:16.237158 172.16.2.8.32924 > 66.33.1.213.25: . ack 36 win 5840
> <nop,nop,timestamp 1925211 1738917217> (DF) [tos 0x10]
> 
> 
> Geoffrey said:
> > John Wells wrote:
> >> Pardon me for jumping in as well, but I'm on Bellsouth and can reach
> >> any box running smtp via port 25.  If they were blocking outbound 25,
> >> I wouldn't be able to telnet to other boxes' port 25, correct?  I can.
> >
> > Telnet is going out 23.
> >
> 
> 
> 
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-- 
James P. Kinney III   \Changing the mobile computing world/
President and CEO      \          one Linux user         /
Local Net Solutions,LLC \           at a time.          /
770-493-8244             \.___________________________./

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics) <jkinney at localnetsolutions.com>
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