Connections reset

[Vu Pham]

I have a strange problem and could not figure out why.
My Linux server is RHEL3 and it needs to print to different wired printers
and wireless printers.

Every two or three weeks it stops printing to all wireless printers. This
makes me think the problem is somewhere on the wireless system but at the
same time, all other  connections from the server to other wireless devices
still work normally. So I narrow down the problem to only the wireless
printers. 

Resetting the acesspoints, the printers... could not help, but the problem
is solved when I restart the Linux server !!! Always !

When the problem happens, it shows that the server refuses all Sync/Ack
packets from the printer that the server sends the SYN packets to. 


Below is an example:

[root at pepper root]# tcpdump -i eth1 port 515 and host 192.168.248.46
tcpdump: listening on eth1
08:56:34.839919 pepper.43259 > 192.168.248.46.printer: S
3784046275:3784046275(0) win 5840 <mss 1460,sackOK,timestamp 141255161
0,nop,wscale 0> (DF) [tos 0x10] 
08:56:35.084115 192.168.248.46.printer > pepper.43259: S
46194689:46194689(0) ack 3784046276 win 5840 <mss 1482,timestamp 32511
1643708416,nop,nop>
08:56:35.084170 pepper.43259 > 192.168.248.46.printer: R
3784046276:3784046276(0) win 0 (DF)


In which case the server will refuse the SYN/ACK ?


Thanks,

Vu