rsync error: error in rsync protocol data stream (code 12) at io.c(463)

[Vlad Sweet]

My setup rsync --version 2.5.5
on client and server
client is behind firewall/nat

on client I run:
rsync -av --progress 110mb_file.mov user1 at box.example.com::dir1
on server:
rsync --daemon

it asks for password, starts to transfer the file, and at about 80% gives me
this error message:

<<==cut==>>
Password:
building file list ...
1 file to consider
110mb_file.mov
rsync: error writing 4 unbuffered bytes - exiting: Connection reset by peer
rsync error: error in rsync protocol data stream (code 12) at io.c(463)
<<==cut==>>

after starting the transfer I monitored it with tcpdump on the server ...
where right about at 87% complete (--progress) i end up with following
tcpdump lines on the server, correct me if I'm wrong, but it looks like at
some point (87% through) my server started advertising TCP window of zero
size (win 0), and client timesout or something and gave the error:

<<==cut==>>
17:29:28.265592 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.266160 192.168.1.100.36310 > box.example.com.rsync: .
102467925:102469373(1448) ack 94 win 5840 <nop,nop,timestamp 1985904015
26099400> (DF)
17:29:28.266212 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.266770 192.168.1.100.36310 > box.example.com.rsync: .
102469373:102470821(1448) ack 94 win 5840 <nop,nop,timestamp 1985904015
26099400> (DF)
17:29:28.266821 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.268887 192.168.1.100.36310 > box.example.com.rsync: .
102470821:102472269(1448) ack 94 win 5840 <nop,nop,timestamp 1985904017
26099400> (DF)
17:29:28.268939 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.269484 192.168.1.100.36310 > box.example.com.rsync: .
102472269:102473717(1448) ack 94 win 5840 <nop,nop,timestamp 1985904017
26099400> (DF)
17:29:28.269536 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.270718 192.168.1.100.36310 > box.example.com.rsync: .
102473717:102475165(1448) ack 94 win 5840 <nop,nop,timestamp 1985904019
26099400> (DF)
17:29:28.270769 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.271309 192.168.1.100.36310 > box.example.com.rsync: .
102475165:102476613(1448) ack 94 win 5840 <nop,nop,timestamp 1985904019
26099400> (DF)
17:29:28.271362 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.272825 192.168.1.100.36310 > box.example.com.rsync: P
102476613:102478061(1448) ack 94 win 5840 <nop,nop,timestamp 1985904020
26099400> (DF)
17:29:28.272877 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.273900 192.168.1.100.36310 > box.example.com.rsync: .
102478061:102479509(1448) ack 94 win 5840 <nop,nop,timestamp 1985904020
26099400> (DF)
17:29:28.273952 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.274998 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.275592 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.276221 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.276828 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.277437 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
17:29:28.278042 box.example.com.rsync > 192.168.1.100.36310: R
1665045802:1665045802(0) win 0 (DF)
<<==cut==>>

so it does transfer about 90Mb before giving me this error. I also installed
rsync-2.5.6 on both client and server - still same problem. rpms i used:
rsync-2.5.5-1.i386.rpm and rsync-2.5.6-4.i386.rpm
uname -a on client:
Linux 2.4.18-14 #1 Wed Sep 4 12:13:11 EDT 2002 i686 athlon i386 GNU/Linux
uname -a on server:
Linux 2.4.20-8 #1 Thu Mar 13 17:54:28 EST 2003 i686 i686 i386 GNU/Linux
RAM on client 512MB, server 128MB

top on sever during transfer never showed more than 0.7 %MEM utilization for
rsync, %CPU 5-8%
df shows plenty of space left and permissions are full rwx for that user and
group.
I tested file transfer several times, at all times transfer would stop at
the same 87%
I should mention that rsync worked with smaller files size under 10 mb. I
did not test other sizes.
Could anyone point me in the right direction here, I'm way over my head
here. please help!
Vlad
Network Admin