Re: ssh & select() problem on 5.3

From: Alin-Adrian Anton (aanton_at_spintech.ro)
Date: 11/28/04

  • Next message: Ricardo Alves dos Reis: "[Fwd: Netgrafh ng_mppc, disabling node!!]" 
    Date: Sun, 28 Nov 2004 20:30:03 +0200
To: Barney Wolff <barney@databus.com>, freebsd-current@freebsd.org, freebsd-hackers@freebsd.org

    Hi,

    Barney Wolff wrote:
    >
    > Perhaps an MTU problem, with the ICMP "fragmentation needed but DF set"
    > being blocked by the firewall? It would only show up when the server
    > has enough to send to fill a packet.
    >

    I'm the friend he was talking about.

    The very same thing happens when the firewall is disabled.

    I tried from 5.2.1 console and same thing happens. However, we were
    unable to reproduce the problem on any other servers. It only happens there.

    No, it's not an ssh bug. I wrote a connect-back snippet and the same
    thing happens when running commands with relatively big output (like dmesg).

    I tried logging from 5.2.1 and 5.3 to different servers behind his
    firewall, running also 5.3 and 5.2.1. The results are similar for all
    the possible combinations.

    A tcpdump shows that what actually happens is that packets won't reach
    me in spite of the fact that his firewall(router)'s tcpdump shows that
    he keeps sending them to me. Packets never reach me, but I am still able
    to send them, by pressing ENTER on the ssh console.

    Interesting fact is that I also get ACK packets for each of the packet I
    send by pressing ENTER. However this is useless, as the connection is
    already desynced and I receive no output. The connection times out in 5
    minutes.

    I hope I didn't use a way too obfuscated English.

    PS: I personally suspect a hardware failure, probably an ethernet card,
    and he is going to check this out tomorrow.

    Regards, 

    -- 
Alin-Adrian Anton
Spintech Systems
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