# Firewall blocking issue port 0

**URL:** <https://forum.sierrawireless.com/t/firewall-blocking-issue-port-0/14486>\
**Category:** AirLink routers\
**Created:** [November 16, 2018, 2:17pm UTC](https://forum.sierrawireless.com/t/firewall-blocking-issue-port-0/14486 "2018-11-16T14:17:48Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ansaldosts](https://avatars.discourse-cdn.com/v4/letter/a/8e7dd6/32.png) [@ansaldosts](https://forum.sierrawireless.com/u/ansaldosts)\
**Post date:** [November 16, 2018, 2:17pm UTC](https://forum.sierrawireless.com/t/firewall-blocking-issue-port-0/14486/1 "2018-11-16T14:17:48Z")

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we have serveral es440 with firmware 4.4.8.005. we use the serial port a lot.  
there are many hack attempts to port 0. which the modem allows to pass. we have tried to block port 0, and then tried to block all ports except the ones we use. in either case the modem makes the hackers connection to port 0. then the hacker tries to send data which eventually locks up the modem port. to correct this we have to reboot the modem.  
I think this is a flaw in the firmware which does not block port 0  
here is a partial log event  
Nov 14 19:54:59 debug ALEOS\_SERIAL\_HMC: Socket 65535 IP: 45.109.111.100 Port 0 Connection Manager state: 1  
Nov 14 19:54:59 info ALEOS\_SERIAL\_HMC: Connect to IP: 45.109.111.100 Port 0

need HELP! any ideas

thanks

vince