Hi David,
thanks for your hint. This seems not to be the problem. The NIC and
the router both have MTU 1492 and ping does work with that. I don't
have a firewall running on my Linux box. I use dhcp offered by the
router.
This is a frame containing an http request which will time out.
Frame number : 7
Frame timestamp: 13:32:19.388097
Frame length : 78 bytes
MAC:
MAC: Header Type : Ethernet MAC Header
MAC: Source Address : aa:aa:03:00:00:00
MAC: Vendor / Broadcast : unknown
MAC: Destination Address : my NIC's Hardware Address
MAC: Vendor / Broadcast : unknown
MAC: Type / Length : 0x0800 - Internet Protocol (IP)
MAC: Frame Status : good
MAC: Additional information :
MAC:
IP:
IP: Header Type : IPv4 Header
IP: Version : 4
IP: Header Length : 5 x 32 bit (20 bytes)
IP: Type Of Service (TOS) : 0x00
IP: Precedence : 0
IP: Name : routine
IP: minimize delay : 0 (unset)
IP: maximize throughput : 0 (unset)
IP: maximize reliability : 0 (unset)
IP: minimize monetary costs : 0 (unset)
IP: Total Length : 60 bytes
IP: Identification : 0xD458
IP: Fragmentation: Offset : 0 (8 byte units)
IP: Fragmentation: DF : 1 (set)
IP: Fragmentation: MF : 0 (unset)
IP: Time To Live (TTL) : 64
IP: Protocol : 6
IP: Name : TCP - Transmission Control
Protocol
IP: Header Checksum : 0x1795
IP: Status : good
IP: Source IP Address : 192.168.0.2
IP: Destination IP Address : 192.25.206.10
IP: IP Options present : no
IP:
TCP:
TCP: Header Type : TCP Header
TCP: Source Port : 32833
TCP: Service :
TCP: Destination Port : 80
TCP: Service : www
TCP: Sequence Number : 0x77F949BA
TCP: Acknowledgement Number : 0x00000000
TCP: Header Length : 10 x 32 bit (40 bytes)
TCP: Unused Field : 0x00
TCP: Control : 0xC2
TCP: end of connection : 0 (no)
TCP: syncronize seq. numbers : 1 (yes)
TCP: reset connection : 0 (no)
TCP: segment requests a push : 0 (no)
TCP: ack. number is valid : 0 (no)
TCP: urgent pointer is valid : 0 (no)
TCP: Window Size : 3440 bytes
TCP: Checksum : 0x09A8
TCP: Status : good
TCP: Urgent Pointer : 0x0000
TCP: TCP Options present : yes
TCP: Size of TCP Options : 20
TCP: Type : 2
TCP: Name : Maximum Segment Size
TCP: Length : 4
TCP: Value : 860
TCP: Type : 4
TCP: Name : SACK-Permitted
TCP: Length : 2
TCP: Type : 8
TCP: Name : Timestamps Option
TCP: Length : 10
TCP: Timestamp : 237936
TCP: Timestamp Reply : 0
TCP: Type : 1
TCP: Name : No Operation
TCP: Length : 1
TCP: Type : 3
TCP: Name : Window Scale
TCP: Length : 3
TCP: Shift Count : 0
thank you, Joerg
(E-Mail Removed) (David Efflandt) wrote in message news:<(E-Mail Removed)>...
> On 23 Aug 2003 04:22:55 -0700, joerg-t <(E-Mail Removed)> wrote:
> > Hi Linux friends,
> >
> > I have a linux box running Debian 3.0. It was working fine directly
> > connected to the DSL modem. But since I installed a router I can ping
> > to the outside world and also name resolution is working but no ftp,
> > www, telnet etc. The requests just times out - no response from the
> > destination hosts. A W2K box in the same LAN works fine.
>
> Does your Linux use dhcp to get IP address from router, or static IP
> outside of dhcp assigned range. Check the dhcp assigned range of your
> router and make sure that any static IP set is not within dhcp range.
>
> But if you have a very strict Linux firewall, you may have an mtu path
> discovery problem, and your Linux is set to drop fragmented packets.
> Assuming your router is doing PPPoE, which has an 8-byte header, max mtu
> of PPPoE is 1492 (might be less, but not more).
>
> Use ping to find max mtu (max mtu is -s + 28). First try:
>
> ping -c 1 -s 1472 -M do internet.host
>
> If that fails and does not reveal actual mtu, try -s 1464. If that still
> fails, try smaller -s until it works. Then add 28 and set mtu of nic to
> router at that number. For example if -s 1464 works (1464 + 28 = 1492):
>
> ifconfig eth0 mtu 1492
>
> If that works, you need to include something in settings or scripts that
> normally bring up that interface.
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