# # (SCO Unix) TCP/IP gives messages like 'Notice: TCP SUM: SRC89270107
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© December 2003 (various)

This article is from a FAQ concerning SCO operating systems. While some of the information may be applicable to any OS, or any Unix or Linux OS, it may be specific to SCO Xenix, Open There is lots of Linux, Mac OS X and general Unix info elsewhere on this site: Search this site is the best way to find anything.

TCP/IP gives messages like "Notice: TCP SUM: SRC 89270107 SUM 0000D7AD" (Old Sco Unix)

This simply means that TCP detected a checksum error in a packet. TCP is a reliable protocol and will automatically request that the packet be re-sent. This message serves as a notice only and should not be of concern unless it occurs frequently. If you wish to determine the IP address of the machine that sent the bad packet, convert the SRC field from hexadecimal ( to decimal ( There are two common causes for these on high-speed networks, which are flaky network cards and slow cards that can't keep up with network traffic. Also, these messages are common on SLIP and PPP links.

Under Unix, at least, you may be able to stop the system from printing these errors. In /etc/conf/pack.d/tcp/space.c, find the line which reads int tcpprintfs = 1; and change the 1 to a 0. Relink the kernel and reboot. I don't know of any similar procedure under Xenix ...

In OpenServer Release 5, this variable defaults to zero (i.e. not printing these diagnostics). It can be adjusted without a reboot using inconfig.

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