Very Computer

I'm having a strange problem with my network connection between my two
linux machines. This describes the problem: I have two following linux
machines connected:

server (debian - testing), eth1=192.168.0.1, eth0 connected to net
client (redhat 7.2), eth0=192.168.0.10 connected to server eth1

The server machine works also as a masqurading server. The symptoms of
the problem is, that I can not transfer large files to server from the
client. What I can do is

1. transfer files without problems from the net into and out of the
   server (so eth0 on server works as expected)
2. transfer files without problems from the net into client.
3. transfer anything using any tool from server to client or net to
   client
4. transfer small files (a few kb) from client to server, but if I
   try anything bigger, it results in a 0 byte file in the server
   machine disk.
5. Connect from client to server using vnc or ssh

I have tried to use nfs, ftp (from both server and client) and scp to
transfer files from client to server. The error messages I've received
are:

trying to copy file from client to nfs mounted share on server:
input/output error

trying to upload file via ftp from client ot server: unable to write on
socket.

The firewall rules on the server machine are flushed. I've tried two
different network adaptors for the eth1 on the server machine. I've
tried to search for the logs of the server to no avail. I'm clueless
and would appreciate any help.

--vh

won't be firewall as you are getting some data.

can you run a tcpdump -v -n -i eth1 on the server and whilst it is
running do an ftp that fails.  When it fails ctrl-C tcpdump and email
the the output to us.  It might be too big to post.

karl.

Hello,

Thanks for helping me out again. I'm really pissed of with this problem.
Anyway, heres the log of the tcpdump. I let the ftp transfer go on for
about 10 minutes before I cut it off. I hope you can read something from
this.

Thanks in advance,
 --vh

---------------------------
tcpdump: listening on eth1
21:31:10.093443 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 2755942364:2755942370(6) ack 3186736991 win 63712 <nop,nop,timestamp 1160795 28447259> (DF) (ttl 64, id 50950, len 58)
21:31:10.093840 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 6 win 5792 <nop,nop,timestamp 28447307 1160795> (DF) (ttl 64, id 5173, len 52)
21:31:10.111397 192.168.0.1.5901 > 192.168.0.10.32773: P 1:87(86) ack 6 win 5792 <nop,nop,timestamp 28447308 1160795> (DF) (ttl 64, id 5174, len 138)
21:31:10.112274 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 6:16(10) ack 87 win 63712 <nop,nop,timestamp 1160797 28447308> (DF) (ttl 64, id 50951, len 62)
21:31:10.112891 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 16:22(6) ack 87 win 63712 <nop,nop,timestamp 1160797 28447308> (DF) (ttl 64, id 50952, len 58)
21:31:10.152552 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 22 win 5792 <nop,nop,timestamp 28447313 1160797> (DF) (ttl 64, id 5175, len 52)
21:31:10.152954 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 22:28(6) ack 87 win 63712 <nop,nop,timestamp 1160801 28447313> (DF) (ttl 64, id 50953, len 58)
21:31:10.153106 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 28 win 5792 <nop,nop,timestamp 28447313 1160801> (DF) (ttl 64, id 5176, len 52)
21:31:10.153312 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 28:34(6) ack 87 win 63712 <nop,nop,timestamp 1160801 28447313> (DF) (ttl 64, id 50954, len 58)
21:31:10.153439 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 34 win 5792 <nop,nop,timestamp 28447313 1160801> (DF) (ttl 64, id 5177, len 52)
21:31:10.172750 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 34:40(6) ack 87 win 63712 <nop,nop,timestamp 1160803 28447313> (DF) (ttl 64, id 50955, len 58)
21:31:10.173083 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 40 win 5792 <nop,nop,timestamp 28447315 1160803> (DF) (ttl 64, id 5178, len 52)
21:31:10.192686 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 40:46(6) ack 87 win 63712 <nop,nop,timestamp 1160805 28447315> (DF) (ttl 64, id 50956, len 58)
21:31:10.193015 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 46 win 5792 <nop,nop,timestamp 28447317 1160805> (DF) (ttl 64, id 5179, len 52)
21:31:10.213157 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 46:52(6) ack 87 win 63712 <nop,nop,timestamp 1160807 28447317> (DF) (ttl 64, id 50957, len 58)
21:31:10.213485 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 52 win 5792 <nop,nop,timestamp 28447319 1160807> (DF) (ttl 64, id 5180, len 52)
21:31:10.232716 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 52:58(6) ack 87 win 63712 <nop,nop,timestamp 1160809 28447319> (DF) (ttl 64, id 50958, len 58)
21:31:10.233048 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 58 win 5792 <nop,nop,timestamp 28447321 1160809> (DF) (ttl 64, id 5181, len 52)
21:31:10.253124 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 58:64(6) ack 87 win 63712 <nop,nop,timestamp 1160811 28447321> (DF) (ttl 64, id 50959, len 58)
21:31:10.253458 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 64 win 5792 <nop,nop,timestamp 28447323 1160811> (DF) (ttl 64, id 5182, len 52)
21:31:10.273007 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 64:70(6) ack 87 win 63712 <nop,nop,timestamp 1160813 28447323> (DF) (ttl 64, id 50960, len 58)
21:31:10.273335 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 70 win 5792 <nop,nop,timestamp 28447325 1160813> (DF) (ttl 64, id 5183, len 52)
21:31:10.293020 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 70:76(6) ack 87 win 63712 <nop,nop,timestamp 1160815 28447325> (DF) (ttl 64, id 50961, len 58)
21:31:10.293350 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 76 win 5792 <nop,nop,timestamp 28447327 1160815> (DF) (ttl 64, id 5184, len 52)
21:31:10.312608 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 76:82(6) ack 87 win 63712 <nop,nop,timestamp 1160817 28447327> (DF) (ttl 64, id 50962, len 58)
21:31:10.312947 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 82 win 5792 <nop,nop,timestamp 28447329 1160817> (DF) (ttl 64, id 5185, len 52)
21:31:10.313390 192.168.0.1.5901 > 192.168.0.10.32773: P 87:173(86) ack 82 win 5792 <nop,nop,timestamp 28447329 1160817> (DF) (ttl 64, id 5186, len 138)
21:31:10.314219 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 82:92(10) ack 173 win 63712 <nop,nop,timestamp 1160817 28447329> (DF) (ttl 64, id 50963, len 62)
21:31:10.332522 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 92:98(6) ack 173 win 63712 <nop,nop,timestamp 1160819 28447329> (DF) (ttl 64, id 50964, len 58)
21:31:10.352510 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 98 win 5792 <nop,nop,timestamp 28447333 1160817> (DF) (ttl 64, id 5187, len 52)
21:31:10.353215 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 98:104(6) ack 173 win 63712 <nop,nop,timestamp 1160821 28447333> (DF) (ttl 64, id 50965, len 58)
21:31:10.353501 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 104 win 5792 <nop,nop,timestamp 28447333 1160821> (DF) (ttl 64, id 5188, len 52)
21:31:10.372694 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 104:110(6) ack 173 win 63712 <nop,nop,timestamp 1160823 28447333> (DF) (ttl 64, id 50966, len 58)
21:31:10.373044 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 110 win 5792 <nop,nop,timestamp 28447335 1160823> (DF) (ttl 64, id 5189, len 52)
21:31:10.392801 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 110:116(6) ack 173 win 63712 <nop,nop,timestamp 1160825 28447335> (DF) (ttl 64, id 50967, len 58)
21:31:10.393091 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 116 win 5792 <nop,nop,timestamp 28447337 1160825> (DF) (ttl 64, id 5190, len 52)
21:31:10.412566 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 116:122(6) ack 173 win 63712 <nop,nop,timestamp 1160827 28447337> (DF) (ttl 64, id 50968, len 58)
21:31:10.412898 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 122 win 5792 <nop,nop,timestamp 28447339 1160827> (DF) (ttl 64, id 5191, len 52)
21:31:10.432578 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 122:128(6) ack 173 win 63712 <nop,nop,timestamp 1160829 28447339> (DF) (ttl 64, id 50969, len 58)
21:31:10.432913 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 128 win 5792 <nop,nop,timestamp 28447341 1160829> (DF) (ttl 64, id 5192, len 52)
21:31:10.452332 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 128:134(6) ack 173 win 63712 <nop,nop,timestamp 1160831 28447341> (DF) (ttl 64, id 50970, len 58)
21:31:10.452639 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 134 win 5792 <nop,nop,timestamp 28447343 1160831> (DF) (ttl 64, id 5193, len 52)
21:31:10.472498 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 134:140(6) ack 173 win 63712 <nop,nop,timestamp 1160833 28447343> (DF) (ttl 64, id 50971, len 58)
21:31:10.472786 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 140 win 5792 <nop,nop,timestamp 28447345 1160833> (DF) (ttl 64, id 5194, len 52)
21:31:10.492911 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 140:146(6) ack 173 win 63712 <nop,nop,timestamp 1160835 28447345> (DF) (ttl 64, id 50972, len 58)
21:31:10.493200 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 146 win 5792 <nop,nop,timestamp 28447347 1160835> (DF) (ttl 64, id 5195, len 52)
21:31:10.512501 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 146:152(6) ack 173 win 63712 <nop,nop,timestamp 1160837 28447347> (DF) (ttl 64, id 50973, len 58)
21:31:10.512784 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 152 win 5792 <nop,nop,timestamp 28447349 1160837> (DF) (ttl 64, id 5196, len 52)
21:31:10.532277 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 152:158(6) ack 173 win 63712 <nop,nop,timestamp 1160839 28447349> (DF) (ttl 64, id 50974, len 58)
21:31:10.532593 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 158 win 5792 <nop,nop,timestamp 28447351 1160839> (DF) (ttl 64, id 5197, len 52)
21:31:10.551978 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 158:164(6) ack 173 win 63712 <nop,nop,timestamp 1160841 28447351> (DF) (ttl 64, id 50975, len 58)
21:31:10.552261 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 164 win 5792 <nop,nop,timestamp 28447352 1160841> (DF) (ttl 64, id 5198, len 52)
21:31:10.572759 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 164:170(6) ack 173 win 63712 <nop,nop,timestamp 1160843 28447352> (DF) (ttl 64, id 50976, len 58)
21:31:10.573304 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 170 win 5792 <nop,nop,timestamp 28447355 1160843> (DF) (ttl 64, id 5199, len 52)
21:31:10.591938 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 170:176(6) ack 173 win 63712 <nop,nop,timestamp 1160845 28447355> (DF) (ttl 64, id 50977, len 58)
21:31:10.592469 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 176 win 5792 <nop,nop,timestamp 28447356 1160845> (DF) (ttl 64, id 5200, len 52)
21:31:10.612080 192.168.0.10.32773 > 192.168.0.1.5901: P [tcp sum ok] 176:182(6) ack 173 win 63712 <nop,nop,timestamp 1160847 28447356> (DF) (ttl 64, id 50978, len 58)
21:31:10.612701 192.168.0.1.5901 > 192.168.0.10.32773: . [tcp sum ok] ack 182 win 5792 <nop,nop,timestamp 28447359 1160847> (DF) (ttl 64, id 5201, len 52)
21:31:10.631662 192.168.0.10.32773 > ...

read more »

You forgot the last bit :(

Quote:

> Hello,

> Thanks for helping me out again. I'm really pissed of with this
> problem. Anyway, heres the log of the tcpdump. I let the ftp
> transfer go on for about 10 minutes before I cut it off. I hope you
> can read something from this.

in summary

Well there's pop3 traffic in there as well, seems to of transferred
an email though, no confidential details you will be glad to here.

There's a gap of 10mins in the FTP streams, in which time pop3, arp
and some other traffic occur, no other FTP related traffic appears in
that time.

When it's talking it's consistent, baring this 10min gap in the
middle, no retransmissions are occurring which indicates that from an
IP level the data transfer is fine.

Each of the FTP packets is transferring a very small payload, usually
less than 30bytes, which along with the fact that no retransmissions
are occuring smells like the the applications are screwing up.

what are the ftp server/client you are using and what kernel
versions.  Have you done any tweaking on any of the boxes, ie changes
to /proc or sysctl

karl.

Actually I did try to send it to your e-mail address (and I did remove
that bit) but the domain wasn't recognized.

Quote:

> in summary

> Well there's pop3 traffic in there as well, seems to of transferred an
> email though, no confidential details you will be glad to here.

You're right, it was a stupid idea to send it here.

Quote:

> There's a gap of 10mins in the FTP streams, in which time pop3, arp and
> some other traffic occur, no other FTP related traffic appears in that
> time.

> When it's talking it's consistent, baring this 10min gap in the middle,
> no retransmissions are occurring which indicates that from an IP level
> the data transfer is fine.

> Each of the FTP packets is transferring a very small payload, usually
> less than 30bytes, which along with the fact that no retransmissions are
> occuring smells like the the applications are screwing up.

> what are the ftp server/client you are using and what kernel versions.
> Have you done any tweaking on any of the boxes, ie changes to /proc or
> sysctl

> karl.

It's kind of hard for me to believe that it's due to the applications I'm
using since I've tried so many different ways to do the transfer. But
anyway, I'm using proftpd on the server and ncftp client on the 'client'.
The only 'tweaking' I've done is that I've compiled a new kernel (2.4.14)
on the server. Could the problem relate to some invalid parameters in the
kernel config?

--vh

I did get some emails late yesterday, so it was probably the mail
server at the ISP playing up. I did eventually get it this morning.
It maybe due to the BT*up yesterday.

Quote:

>> There's a gap of 10mins in the FTP streams, in which time pop3, arp
>> and some other traffic occur, no other FTP related traffic appears
>> in that time.

>> When it's talking it's consistent, baring this 10min gap in the
>> middle, no retransmissions are occurring which indicates that from
>> an IP level the data transfer is fine.

>> Each of the FTP packets is transferring a very small payload,
>> usually less than 30bytes, which along with the fact that no
>> retransmissions are occuring smells like the the applications are
>> screwing up.

>> what are the ftp server/client you are using and what kernel
>> versions. Have you done any tweaking on any of the boxes, ie
>> changes to /proc or sysctl

>> karl.

> It's kind of hard for me to believe that it's due to the
> applications I'm using since I've tried so many different ways to do
> the transfer. But anyway, I'm using proftpd on the server and ncftp
> client on the 'client'. The only 'tweaking' I've done is that I've
> compiled a new kernel (2.4.14) on the server. Could the problem
> relate to some invalid parameters in the kernel config?

With an FTP transfer the payloads should be in the order of 1400+, at
best you were transferring 200-300 bytes for a short time.
fragmentation isn't occurring and 1400+ byte packets are going
through, a side effect of the pop3 transfer.

I don't think the server is at issue, as the transfers are from
client (.10) to server (.1).  I don't think that 2.4.14 would be an
issue.

I would run a few tests

a tcpdump -v -n -i eth1   on the server
a tcpdump -n -n -i eth0   on the client
strace -f -tt -o output -p ncftp <server>
ifconfig

do other ftp clients exhibit the same issue?

The FTP username/password may appear in the output file, if you are
concerned about security.  Look for USER and PASS.

What NIC do you use, I can't think of anything NIC related that would
show this problem though.

Also this will probably be alot of output so email is best.  I think
my ISP is sorted out now.

karl.