Re: weird network problem in FC4

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On Wed, 2005-07-06 at 01:02 -0400, Amadeus W. M. wrote:
> Ever since I moved to this ISP I've been having network problems, and I
> need a little help.
> 
> They gave me an antique motorolla cable modem, and usually I have a
> linksys router plugged into the router, but right now I have my FC4 pc
> plugged in directly into the modem, to rule out any problems with the
> router. 
> 
> For the last couple of days the connection was ok, but this afternoon it
> rained, and, since my ISP's service seems to depend on the weather, the
> network went down. If it rains, it goes down, if it's windy, it goes down,
> if there's lightening, you guessed it, it goes down. It's an ISP from hell.
> 
> Now I've configured eth0 with dhcp. It does get an IP address, but when I
> try to connect anywhere, it says network unreachable:
> 
> ssh: connect to host cse port 22: Network is unreachable
> 
> I see network activity in gkrellm and I see ARP packets with ethereal,
> so the link is ok. So I look at the routing table, and I see no default
> gateway:
> 
> 12) root:~> route -n
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
> 24.35.40.0      0.0.0.0         255.255.248.0   U     0      0        0 eth0
> 169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0
> 
> I have absolutely no idea where the 168.254.0.0 came from. I did see this
> happening in windows, a long time ago. All I did in the network
> configuration tool was to click on get IP automatically with dhcp. 
> 
> Anyway, I did see some DHCP packets with ethereal coming in, among
> countless ARP packets (Who has xxx, Tell yyy), so I figured that must be
> the gateway. Manually, I do 
> 
> route add default gateway xx.xx.xx.xx
> 
> and then voila! I'm online.
> 
> Now that I got this far, I want to pinpoint where the problem is. 
> Why am I not getting the default gateway? Is it some bug in my FC4 dhcp
> client, or is my stupid ISP that's not sending it. Is it possible to tell?
> 
> For what it's worth, I installed the dhcp server on this machine (FC2,
> just prior to FC4), and my other machines as well as the router got all
> the required info just fine. I do want to go out through the router
> though, and I want it to get all the info, as it should. I am positive my
> hardware is ok, except possibly the motorolla cable modem, which is from
> the ISP.
> 
> Below is the DHCP packet I saw with ethereal. Please someone help, before
> I end up in a mad house.
> 
> 
> No.     Time        Source                Destination           Protocol Info
>    4693 186.355671  24.35.40.1            255.255.255.255       DHCP     DHCP Offer    - Transaction ID 0x33d1a0
> 
> Frame 4693 (363 bytes on wire, 363 bytes captured)
>     Arrival Time: Jul  5, 2005 19:52:47.244828000
>     Time delta from previous packet: 0.120903000 seconds
>     Time since reference or first frame: 186.355671000 seconds
>     Frame Number: 4693
>     Packet Length: 363 bytes
>     Capture Length: 363 bytes
>     Protocols in frame: eth:ip:udp:bootp
> Ethernet II, Src: 00:50:57:00:99:a6, Dst: ff:ff:ff:ff:ff:ff
>     Destination: ff:ff:ff:ff:ff:ff (Broadcast)
>     Source: 00:50:57:00:99:a6 (Broadban_00:99:a6)
>     Type: IP (0x0800)
> Internet Protocol, Src Addr: 24.35.40.1 (24.35.40.1), Dst Addr: 255.255.255.255
> (255.255.255.255)
>     Version: 4
>     Header length: 20 bytes
>     Differentiated Services Field: 0x07 (DSCP 0x01: Unknown DSCP; ECN: 0x03)
>         0000 01.. = Differentiated Services Codepoint: Unknown (0x01)
>         .... ..1. = ECN-Capable Transport (ECT): 1
>         .... ...1 = ECN-CE: 1
>     Total Length: 349
>     Identification: 0x0000 (0)
>     Flags: 0x00
>         0... = Reserved bit: Not set
>         .0.. = Don't fragment: Not set
>         ..0. = More fragments: Not set
>     Fragment offset: 0
>     Time to live: 16
>     Protocol: UDP (0x11)
>     Header checksum: 0x6966 (correct)
>     Source: 24.35.40.1 (24.35.40.1)
>     Destination: 255.255.255.255 (255.255.255.255)
> User Datagram Protocol, Src Port: bootps (67), Dst Port: bootpc (68)
>     Source port: bootps (67)
>     Destination port: bootpc (68)
>     Length: 329
>     Checksum: 0x6b77 (correct)
> Bootstrap Protocol
>     Message type: Boot Reply (2)
>     Hardware type: Ethernet
>     Hardware address length: 6
>     Hops: 0
>     Transaction ID: 0x0033d1a0
>     Seconds elapsed: 0
>     Bootp flags: 0x8000 (Broadcast)
>         1... .... .... .... = Broadcast flag: Broadcast
>         .000 0000 0000 0000 = Reserved flags: 0x0000
>     Client IP address: 0.0.0.0 (0.0.0.0)
>     Your (client) IP address: 24.35.42.93 (24.35.42.93)
>     Next server IP address: 0.0.0.0 (0.0.0.0)
>     Relay agent IP address: 24.35.40.1 (24.35.40.1)
>     Client MAC address: 00:12:17:32:ea:79 (Cisco-Li_32:ea:79)
>     Server host name not given
>     Boot file name not given
>     Magic cookie: (OK)
>     Option 53: DHCP Message Type = DHCP Offer
>     Option 54: Server Identifier = 24.35.0.42
>     Option 51: IP Address Lease Time = 6 days, 23 hours, 59 minutes, 55 seconds
>     Option 1: Subnet Mask = 255.255.248.0
>     Option 5: Name Server
>         IP Address: 24.35.0.12
>         IP Address: 24.35.0.13
>     Option 23: Default IP Time-to-Live = 64
>     Option 27: All Subnets are Local = No
>     Option 28: Broadcast Address = 255.255.255.255
>     Option 31: Perform Router Discover = Enabled
>     Option 35: ARP Cache Timeout = 1 minute
>     Option 37: TCP Default TTL = 64
>     Option 3: Router = 24.35.40.1

---------------^^^^^^^^^^^^^^^^^^^^

That looks like the setting for the default gateway to me.

>     Option 6: Domain Name Server
>         IP Address: 24.35.0.12
>         IP Address: 24.35.0.13
>     Option 44: NetBIOS over TCP/IP Name Server = 127.0.0.1
>     Option 46: NetBIOS over TCP/IP Node Type = H-node
>     End Option

Paul.
-- 
Paul Howarth <paul@xxxxxxxxxxxx>


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