Starnge network issue: TCP doesn't work, UDP does

[Kam Leo]

On 5/6/06, Michael Merwitz <michael.merwitz at gmail.com> wrote:
> OK, so there's an incorrectly configured something or other on my FC machine
> that dtops TCP from working but allows UDP to work just fine.
> I've run through all of the rlevant tools (netstat, tcpdump, ifconfog etc
> etc.), and compared it to anthother machine running FC5, but  cannot for the
> life of me spot the difference.
>
> For example, using firefox to view slashdot, I see the standard UDP traffic
> for DNS.
> Then, TCP SYN from my machine to their srver, ans SYN,ACK from them back to
> me, and finally an ACK from me to them. And then.... nothing. no traffic, no
> response.
> Interestingly, if I try & coinnect to the apache instance on this local
> machine, I don't even get that far... there is no TCP traffic at all.
>
> Also, if I try to use another TCP reliant app, Thunderbird, to connect to a
> local IMAP server (on the same subnet) I get the SYN/ACk/ACK setup, but no
> further traffic.
>
> I have SeLinux set as disabled
> I have no iptables rules in effect.
>
> The only thing that changed is that I did a yum update, installed a new
> video card (nvdia 7300) and the appropriate driver, and rebooted...
>
> Running 2.6.16-1.2107_FC5smp
>
> Please help!!!!
>

1. Read this weeks list postings and you would known there are
problems with the .2107 kernel.
2. You can fix this by either upgrading or using the .2096 kernel
which should still be installed on your system.