Re: Troubleshooting connection loss (novice question)

Tauno Voipio wrote:
Allen Weiner wrote:
Tauno Voipio wrote:

Allen Weiner wrote:

Bit Twister wrote:

On Mon, 29 Oct 2007 18:15:57 GMT, Allen Weiner wrote:

I run Fedora 7 and use Verizon DSL. My modem is a Westell 6100-E90 modem/router. My DSL connection usually runs well, but about once every seven to ten days I lose my Internet connection.



My SWAG, for some reason, you are not renewing your dhcp lease in
the modem. You might root around in the modems web page and see what
you can see.

I can regain my connection by rebooting Fedora. I've not been able to regain my Internet connection without a reboot (e.g. "service network restart" hangs).



Now that is odd, I would have thought it would not matter unless your fedora
firewall gets in the way.

Would you dump your network settings for us to look at.


Here:

(-- extra clipped, TV --)

IN=eth0 OUT= MAC=00:07:e9:01:b2:09:00:18:3a:53:f7:fb:08:00 SRC=192.168.1.1 DST=192.168.1.47 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=8835 DF PROTO=TCP SPT=1288 DPT=80 WINDOW=8192 RES=0x00 SYN URGP=0


Inbound IN=eth0 OUT= MAC=00:07:e9:01:b2:09:00:18:3a:53:f7:fb:08:00 SRC=192.168.1.1 DST=192.168.1.47 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=8836 DF PROTO=TCP SPT=1288 DPT=80 WINDOW=8192 RES=0x00 SYN URGP=0


Your firewall is cutting your router (and all external
traffic via default gateway) off.

It is a good question why the router is attempting to
connect to the HTTP port of your computer.

The (cut-off) rest of the same porridge may have further
clues on what's going on.


Since I'm a novice at both networking and at Linux, I don't have any idea how you concluded from the two above ethernet transmissions that my
firewall (presumably you mean my software firewall Firestarter and not the hardware firewall in the modem/router). Please not that the above data was not recorded at time of connection loss. It was recorded while I had a functioning Internet connection, in order to display my network configuration, as requested in this thread by Bit-Twister.

So. I would not be able to reach any conclusions by looking at more of those ethernet transmissions. But I do have stored in a file the entire output of the mii-tool. If you wish, I can post more of it. Tell me about how many transmissions would be helpful.

For the time being, here are a few more:

<snip>



OK, let's split one report (picked from above):

> Inbound IN=eth0 OUT= MAC=00:07:e9:01:b2:09:00:18:3a:53:f7:fb:08:00
> SRC=192.168.1.1 DST=192.168.1.47 LEN=60 TOS=0x00 PREC=0x00 TTL=64
> ID=8836 DF PROTO=TCP SPT=1288 DPT=80 WINDOW=8192 RES=0x00 SYN URGP=0

Inbound IN=eth0 OUT= <== data into the host via eth0

MAC=00:07:e9:01:b2:09:00:18:3a:53:f7:fb:08:00 <== Ethernet header:
00:07:e9:01:b2:09 destination MAC (computer Ethernet address)
00:18:3a:53:f7:fb source MAC (router Ethernet address)
08:00 payload type: IP packet

SRC=192.168.1.1 <== source IP, router
DST=192.168.1.47 <== destination IP, computer

LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=8836 <== IP parameters

DF PROTO=TCP SPT=1288 DPT=80 WINDOW=8192 RES=0x00 SYN URGP=0

TCP parameters:
- do not fragment
- source port 1288
- destination port 80 (HTTP / WWW)
- receive window 8192 bytes
- SYN packet, attempting connection
- no urgent data

This packet is an attempt from your router to connect to
your computer's HTTP/WWW server, if there is any. I do not
see why a respectable router would attempt such a thing.

As far as I see, all of the listed packets are similar.

The firewall may blacklist your router because of these
attempts.

Maybe your ISP attempts to discover if the clients are
having webservers. Is it prohibited in the contract?


Thanks for the detailed explanation of those messages. I had zero understanding of them.

Yes, my ISP, Verizon, prohibits webservers. I'm using a budget, $15 per month, consumer DSL service.
.

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