I remember I saw this behavior before. Mostly important thing is to find out if the enc/dec goes well. I was having this problem that triggers kernel to send out the icmp.
------------ Banyan He Blog: http://www.rootong.com Email: ban...@rootong.com On 4/10/2013 5:27 PM, yihect wrote: > > Hi, all: > > I'm playing with Gre Tunnel programming in centos 6. > > I wrote my program in these steps: > a, open /dev/net/tun device and ioctl with TUNSETIFF, get fd to tun > device, say "tun0"; > b, create one socket and use it to set tun0's ip address, namyly > SIOCSIFADDR and SIOCSIFDSTADDR; and then turn it up; > c, create one raw socket to send things which got from the tun0 > device to other machine, and to receive packages which should be feeded into > the tun0 device; > > Finally, I ran the program in two machines, say MA and MB, > synchronously, and set route info in MA and MB too. The last environment is > like this: > > 10.0.3.1/24 192.168.0.31/24 192.168.0.124/24 10.0.4.1/24 > ---------- MA ------------------------------------------- MB > ---------- > tun0 eth0 eth0 > tun0 > > When I ping MB in MA, and tcpdump eth0 in MA, I get: > > 15:06:39.712390 IP 192.168.0.31 > 192.168.0.124: GREv0, length 88: IP > 10.0.3.1 > 10.0.4.1: ICMP echo request, id 28797, seq 1, length 64 > 15:06:39.713232 IP 192.168.0.124 > 192.168.0.31: ICMP 192.168.0.124 protocol > 47 port 2048 unreachable, length 116 > 15:06:39.713667 IP 192.168.0.124 > 192.168.0.31: GREv0, length 88: IP > 10.0.4.1 > 10.0.3.1: ICMP echo reply, id 28797, seq 1, length 64 > 15:06:39.713754 IP 192.168.0.31 > 192.168.0.124: ICMP 192.168.0.31 protocol > 47 port 2048 unreachable, length 116 > > The 1st and 3rd lines is easy to understand, but what about the > 2nd and 4th lines??? Is the raw package been sent up into gre protocol while > caught by my program?? > > I have seen ICMP_PORT_UNREACH stuff been placed in ip_gre.c kernel > code, but say it is "Impossible event". So, what's wrong, have I missed > something in my program? Any suggestions are appreciated, thanks. > > > > > _______________________________________________ > CentOS mailing list > CentOS@centos.org > http://lists.centos.org/mailman/listinfo/centos _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
