Hi, I have trouble setting up the gre tunnel. Searching on the archived email database, I found following link describing similiar question: http://www.squid-cache.org/mail-archive/squid-users/200504/0567.html I tried as suggested in above link, but failed. > modprobe ip_gre This command is ok > ip tunnel add wccp mode gre remote ip.of.your.router dev ethX my command is: "iptunnel add gre0 mode gre remote 192.168.4.1 local 192.168.1.100 dev eth0" and the result is: ioctl: No buffer space available What does this mean? Does this means gre0 is already there and I can not add a same gre0 tunnel? And the command "iptunnel change gre0 mode gre ..." command failed with: ioctl: No such file or directory Then I tried "iptunnel add gre1 mode gre remote 192.168.4.1 local 192.168.1.100 dev eth0", where 192.168.4.1 is my router's identifier and 192.168.1.100 is the Fedora server where my squid is sitting on. Now the command is succesfull and bringing up a iptunnel gre1. And my iptable command is: iptables -t nat -A PREROUTING -s 192.168.0.0/16 -i gre1 -p tcp --dport 80 -j REDIRECT --to-port 3128 However, the two interfaces shown by "ifconfig -a" are: gre0 Link encap:UNSPEC HWaddr 00-00-00-00-A3-BF-C8-E7-00-00-00-00-00-00-00-00 UP RUNNING NOARP MTU:1476 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) gre1 Link encap:UNSPEC HWaddr C0-A8-01-64-A3-BF-C8-E7-00-00-00-00-00-00-00-00 UP POINTOPOINT RUNNING NOARP MTU:1476 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) Also I tried "tcpdump -n -i gre1 ip proto gre", there are warnings (are they indicating something?) there: tcpdump: WARNING: arptype 778 not supported by libpcap - falling back to cooked socket tcpdump: WARNING: gre1: no IPv4 address assigned Then no packets are captured by this command All of above seem to indicate none of the two tunnels is capturing anything, right? On the other hand, "tcpdump -n -i eth0 ip proto gre" does capture packets like: IP 192.168.4.1 > 192.168.1.100: GREv0, length 68: gre-proto-0x883e Finally, here is my linux version: # uname -a Linux HOST 2.6.22.14-72.fc6 What's wrong with my configuration? The squid side seems to work fine when I don't use transparent proxy, namely, when I configure proxy server in browsers of client side, the squid access.log records all the succesfully access to squid. Thanks a lot. Sinecerely, Jianw
