Hi All ,
could anybody help me on this , i have check log

UDP: bad checksum. From 83.213.210.58:63744 to 67.18.242.90:421 ulen 1032
NET: 9 messages suppressed.
UDP: bad checksum. From 83.213.210.58:5635 to 67.18.242.90:543 ulen 1032
NET: 8 messages suppressed.
UDP: bad checksum. From 83.213.210.58:60160 to 67.18.242.90:387 ulen 1032
sending pkt_too_big (len[1500] pmtu[1476]) to self
sending pkt_too_big (len[1500] pmtu[1476]) to self
sending pkt_too_big (len[1500] pmtu[1476]) to self
sending pkt_too_big (len[1500] pmtu[1476]) to self
sending pkt_too_big (len[1500] pmtu[1476]) to self
NET: 1 messages suppressed.
221.113.129.50 sent an invalid ICMP error to a broadcast.
sending pkt_too_big (len[1500] pmtu[1476]) to self
sending pkt_too_big (len[1500] pmtu[1476]) to self
sending pkt_too_big (len[1500] pmtu[1476]) to self
application bug: perl(8735) has SIGCHLD set to SIG_IGN but calls wait().
(see the NOTES section of 'man 2 wait'). Workaround activated.
application bug: perl(8735) has SIGCHLD set to SIG_IGN but calls wait().
(see the NOTES section of 'man 2 wait'). Workaround activated.
application bug: perl(8735) has SIGCHLD set to SIG_IGN but calls wait().

Regards
Chandra

From your log messages, it looks like the system is sending mangled packets, but whether that's due to a problem with the network interface or something malicious is unclear. There only appears to be a few messages though, which doesn't explain why you have excessive outbound traffic.

I'd start by firing up ethereal or tcpdump and getting a sample of some of the traffic and see if you can identify the type of traffic and destination.

Also, as root take a listing of current processes running on the system (use ps aux | tee log) and of current networking sockets (netstat -pantu | tee -a log).