SYN_SENT port issue

[Mike Abasolo]

what do syn_sent status in netstat means?

[root@server1:/root]
# netstat -an | grep 8922
tcp 0 1 143.26.128.200.65068 143.26.128.200.8922 SYN_SENT
tcp 0 0 *.8922 *.* LISTEN

I have recieved a ticket that a certain application is having connection timed out while connecting to this port.

[Tue Sep 2 01:01:52 2008] [error] [client 131.190.2.18] (238)Connection timed o
ut: proxy connect to 143.26.128.200 port 8922

Any ideas?


Regards,
Mike

[Mike Abasolo]

Additional details:

[root@server1:/root]
# lsof -i @143.26.128.200:8922
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
httpd 4390 oracle 28u inet 0xa42dcc68 0t0 TCP server1.eu.pg.com:65090->server1.eu.pg.com:8922 (SYN_SENT)

[root@server1:/root]
# ps -ef | grep 4390
oracle 4390 25994 0 00:15:09 ? 0:00 /ias/Apache/Apache/bin/httpd -d /ias/Apache/Apache
root 8768 4614 1 00:30:28 pts/0 0:00 grep 4390

[IG_2]

Hi,

The answer is in your second post. This is an Oracle ias web-server and somebody is trying to access to it without success.

Regards,

[Heironimus · Accepted solution]

The three-way handshake required to establish a new TCP connection involves a SYN from the source, a SYN/ACK from the destination, and a final ACK from the source. SYN_SENT in netstat means the handshake isn't complete, which makes perfect sense when you're getting a connection timeout.

Common reasons are firewalls or network problems. Though it is a little strange to see a connection to the local machine hung up in SYN_SENT....