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To: <cipe-l,AT,inka,DOT,de>
Subject: Re: bad checksum messages..
From: "Hans Steegers" <J.Steegers,AT,chello,DOT,nl>
Date: Sun, 29 Jun 2003 11:17:17 +0200
Reply-to: "Hans Steegers" <steegers,AT,steegers,DOT,nl>

The message orginates from the udp (udp.c) part of the ipv4 TCP/IP protocol
suite in the Linux kernel.
[udp.c:printk(KERN_DEBUG "UDP: bad checksum. From %d.%d.%d.%d:%d to
%d.%d.%d.%d:%d ulen %d\n",..]
Machine 192.168.1.200 is sending malformed UPD-packets to ip-address
10.1.0.3, port 62516. Size is 25 bytes.
CIPE does not check the UDP checksum, leaving it to the TCP/IP stack.

As far I can see, port 62516 is not used by CIPE, so probably it is not
_directly_ related to CIPE. I also can't find the ip-address 192.168.1.200
in your configs, so it seems that the orginating address isn't related to
the CIPE setup too.

Possibly some network configuration error is causing this.

Hans Steegers

-----Original Message-----
From: Doug Johnson <doug.johnson,AT,vifanusa,DOT,com>
To: 'cipe-l,AT,inka,DOT,de' <cipe-l,AT,inka,DOT,de>
Date: Sunday, June 29, 2003 4:08 AM
Subject: UDP: bad checksum messages..

>I am using CIPE-Win32 v2.0-pre15 on a Win2k machine with no problems in
>usage (after the gracious help from many on the list).  I do however see
>some messages on the Linux server that are unusual. In the
/var/log/messages
>file I see the following:
>
>Jun 28 21:03:32 linus kernel: NET: 3 messages suppressed.
>Jun 28 21:10:54 linus kernel: NET: 1 messages suppressed.
>Jun 28 21:22:47 linus kernel: NET: 1 messages suppressed.
>Jun 28 21:28:04 linus kernel: NET: 1 messages suppressed.
>
>Understanding the kernel suppresses like messages sent within 5 seconds I
>found the culprit in dmesg:
>
>cipcb0: cipe_sendmsg
>cipcb0: cipe_recvmsg
>UDP: bad checksum. From 192.168.1.200:62516 to 10.1.0.3:62516 ulen 25
>UDP: bad checksum. From 192.168.1.200:62516 to 10.1.0.3:62516 ulen 25
>UDP: bad checksum. From 192.168.1.200:62516 to 10.1.0.3:62516 ulen 25
>UDP: bad checksum. From 192.168.1.200:62516 to 10.1.0.3:62516 ulen 25
>
>There doesn't seem to be anything unusual in a netstat -a. I am however
>running two cipcb adpaters (cipcb0 and cipcb1) on the Linux server at this
>time. cicpb0 is for LAN to LAN connectivity between a linux server and a
>linux client (which works fine) and cipcb1 is a win2k machine connected to
>the linux server (which so far is working fine).
>
>My question is what am I seeing with the bad checksum and how can I correct
>it?
>
>(other configurations below if needed)
>
>###############  WIN32 CLIENT  ##################
>
>In the adapter settings of the Win2k box:
>IP Address: 10.1.0.4
>Subnet Mask: 255.255.255.0
>Default Gateway: (blank)
>
>DNS Server entries are both blank as well.
>
>In the CIPE Peer setting I have the following info:
>Local IP Addres: 0.0.0.0 Port 6850
>Peer IP Address: 66.43.188.40 Port 6850
>Local PTP Address:10.1.0.4
>Remote PTP Address: 10.1.0.3
>Status Enabled: (checked)
>Static Key (hidden)
>Cipher: Blowfish
>Timeout seconds: 600
>
>#################  LINUX SERVER  ##################
>
>The CIPE server
>options.cipcb0 file:
>
>dynip
>cttl 64
>maxerr -1
>ptpaddr 10.1.0.2
>ipaddr 10.1.0.1
>me vpn.vifanusa.com:6849
>peer 0.0.0.0
>key (hidden)
>
>ifcfg-cipcb0 file:
>
>USERCTL=no
>PEERDNS=no
>TYPE=CIPE
>DEVICE=cipcb0
>ONBOOT=yes
>IPADDR=10.1.0.1
>MYPORT=6849
>PTPADDR=10.1.0.2
>
>options.cipcb1 file:
>
>dynip
>cttl 64
>maxerr -1
>ptpaddr 10.1.0.4
>ipaddr 10.1.0.3
>me vpn.vifanusa.com:6850
>peer 0.0.0.0
>key (hidden)
>
>ifcfg-cipcb1 file:
>
>USERCTL=no
>PEERDNS=no
>TYPE=CIPE
>DEVICE=cipcb1
>ONBOOT=yes
>IPADDR=10.1.0.3
>MYPORT=6850
>PTPADDR=10.1.0.4
>
>##########  REMOTE LAN LINUX CLIENT ##########
>
>options.cipcb0 file:
>
>cttl 64
>maxerr -1
>dynip
>ping 20
>ipaddr 10.1.0.2
>ptpaddr 10.1.0.1
>me 0.0.0.0
>peer vpn.vifanusa.com:6849
>key (hidden)
>
>ifcfg-cipcb0 file:
>
>DEVICE=cipcb0
>ONBOOT=yes
>USERCTL=no
>MYPORT=6849
>PEER=vpn.vifanusa.com:6849
>PTPADDR=10.1.0.1
>IPADDR=10.1.0.2
>
>#################### END ##############################
>
>Thanks much in advance..
>Doug
>
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