wizzz
Intern
Intern
  • UID1308
  • Fans0
  • Follows0
  • Posts3
Reads:1352Replies:4

TCPIP implementation in VPC

Created#
More Posted time:Dec 5, 2016 9:25 AM
Hi,
 In default, Linux enables these TCP headers options - (Timestamp, window scaling, SACK).
When we disable these three options and try to connect vpc100-oss-cn-beijing.aliyuncs.com,
the TCP client cannot receive  SYN-ACK after sending SYN packet.

However, it is okay to connect oss-cn-beijing.aliyuncs.com with disabling these three TCP header options.

Actually, we are developing our TCPIP stack. So we want to know if there is any limitation of TCPIP stack in VPC.

Thanks a lot.

shhanshan
Forum Moderator
Forum Moderator
  • UID105
  • Fans3
  • Follows0
  • Posts209
1st Reply#
Posted time:Dec 8, 2016 8:46 AM
This vpc100-oss-cn-beijing.aliyuncs.com is only an internal address between VPC and ECS. This is the public address:  oss-cn-beijing.aliyuncs.com. So you can connect to  oss-cn-beijing.aliyuncs.com. Thanks

wizzz
Intern
Intern
  • UID1308
  • Fans0
  • Follows0
  • Posts3
2nd Reply#
Posted time:Dec 12, 2016 8:49 AM
Hi,

Thanks for your help.

Actually, we have the right to access vpc100-oss-cn-beijing.aliyuncs.com.

We used a linux box with default setting and it was okay to access it.
However, when we disable these TCP headers options - (Timestamp, window scaling, SACK).

vpc100-oss-cn-beijing.aliyuncs.com didn't resonse SYN-ACK after we sent a SYN packet.

wizzz
Intern
Intern
  • UID1308
  • Fans0
  • Follows0
  • Posts3
3rd Reply#
Posted time:Dec 12, 2016 14:24 PM
More info, in a linux box:

       a. disable TCP options:
               echo 0 > /proc/sys/net/ipv4/tcp_timestamps

               echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

               echo 0 > /proc/sys/net/ipv4/tcp_sack


    b. just use curl
                 curl http://vpc100-oss-cn-beijing.aliyuncs.com

            then, use wireshark or tcpdump and figure out there is no SYN-ACK after sending SYN.

shhanshan
Forum Moderator
Forum Moderator
  • UID105
  • Fans3
  • Follows0
  • Posts209
4Floor#
Posted time:Dec 23, 2016 22:55 PM
Dear customer,

After confirming, we don't suggest to disable the three TCP options. Please put them enable, and continue to develop you own environment.

Thanks
Guest