topic Duplicate TCP SYN from inside ?? in Network Security https://community.cisco.com/t5/network-security/duplicate-tcp-syn-from-inside/m-p/1341376#M779953 <P>Hello all,</P><P>A user can not send e-mail using outlook, but he can retrieve his email.</P><P>I checked the ASA 5505 log and I found a message:</P><P></P><P>4 Oct 15 2009 09:07:18 419002 192.168.106.2 209.210.**.1*0 Duplicate TCP SYN from inside:192.168.106.2/1323 to outside:209.210.**.1*0/25 with different initial sequence number</P><P></P><P>192.168.106.2 is his computer ip address and 209.210.**.1*0 is the smtp server.</P><P></P><P>Does the ASA 5505 block the connection to the SMTP server? Please help!</P><P></P><P>Thank you.</P> Mon, 11 Mar 2019 16:26:19 GMT davidwu2007 2019-03-11T16:26:19Z Duplicate TCP SYN from inside ?? https://community.cisco.com/t5/network-security/duplicate-tcp-syn-from-inside/m-p/1341376#M779953 <P>Hello all,</P><P>A user can not send e-mail using outlook, but he can retrieve his email.</P><P>I checked the ASA 5505 log and I found a message:</P><P></P><P>4 Oct 15 2009 09:07:18 419002 192.168.106.2 209.210.**.1*0 Duplicate TCP SYN from inside:192.168.106.2/1323 to outside:209.210.**.1*0/25 with different initial sequence number</P><P></P><P>192.168.106.2 is his computer ip address and 209.210.**.1*0 is the smtp server.</P><P></P><P>Does the ASA 5505 block the connection to the SMTP server? Please help!</P><P></P><P>Thank you.</P> Mon, 11 Mar 2019 16:26:19 GMT https://community.cisco.com/t5/network-security/duplicate-tcp-syn-from-inside/m-p/1341376#M779953 davidwu2007 2019-03-11T16:26:19Z Re: Duplicate TCP SYN from inside ?? https://community.cisco.com/t5/network-security/duplicate-tcp-syn-from-inside/m-p/1341377#M779970 <HTML><HEAD></HEAD><BODY><P>Verizon, the Internet Services Provider, had changed the SMTP port from 25 to 578. Reconfigure MS Outlook SMTP port to 578 and the problem is gone. </P></BODY></HTML> Thu, 15 Oct 2009 17:59:10 GMT https://community.cisco.com/t5/network-security/duplicate-tcp-syn-from-inside/m-p/1341377#M779970 davidwu2007 2009-10-15T17:59:10Z