Tell me more ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.
up vote 0 down vote favorite

I am facing this issue related to syn without ack back from the server and client keep on sending the syn, connects after three-four retries, i am using java tcp server and cpp client. I cross verified using tcpdump at server for the arrival of the clients SYN packet but found like server machine never received SYN packet,

So how to trace as exactly where the syn packet is missing at our router or other network routers, any help will be appreciated....

share|improve this question
Does your router or firewall have logging turned on? If not, crank it up to 11 and watch for your missing SYN there. – Ladadadada Mar 28 '12 at 7:44
no its not on, and is there any software to capture packets on router like tcpdump?... – ritu Mar 29 '12 at 4:43
Most professional quality routers and firewalls will have the ability to configure a syslog server to send their logs to and once the logging level is turned up high enough, they will log every packet - even the ones they decide to drop. If the problem is outside your network you will have to phone your ISP or the cilent's ISP and ask them where your traffic is. – Ladadadada Mar 29 '12 at 6:32
That said, I once had a problem with an 18-month old bogon list being used to filter the internet at a place where I worked and stopping people from visiting websites. It's unlikely to be your problem, but check to see if your IP address has recently been taken off any bogon lists. – Ladadadada Mar 29 '12 at 6:39
thanks for the response i will check with network admin for the syslog and also for the bogon list, we are having juniper ssg5 router.. – ritu Mar 29 '12 at 10:21
show 1 more comment

Know someone who can answer? Share a link to this question via email, Google+, Twitter, or Facebook.

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.