XCOMU0505E Received a signal from TCP/IP

Products

• XCOM Data Transport
• XCOM Data Transport - Linux PC
• XCOM Data Transport - z/OS

Issue/Introduction

When I attempt to send data to a Linux server the transmission fails with error:

XCOMU0505E Received a signal from TCP/IP

How do I resolve this error?

Environment

XCOM™ Data Transport® for Linux PC

Cause

Incorrect settings in the following files:

/etc/hosts.allow  file contains value   ALL : localhost. 

/etc/hosts.deny   file contains value   ALL : ALL

Note: this is not the only cause of the XCOMU0505E error message but these files are often overlooked as a likely cause.

• Whenever a new incoming request comes into a Linux server, first it will check if there is any rule defined in the /etc/hosts.allow file matching to the request.
• If any match is found, connection will be allowed.
• If no match is found, it will check the /etc/hosts.deny file to see if there is any matching criteria defined.
• If any match is found, connection will be denied.
• If no match is found in both files, connection will be allowed.

In this scenario, XCOM transfers are working fine if loopback transfers are performed with REMOTE_SYSTEM=127.0.0.1 or REMOTE_SYSTEM=localhost.

This is because /etc/hosts.allow has rule ALL : localhost.

XCOM transfers are failing with error XCOMU0505E Received a signal from TCP/IP, when transfers are performed with REMOTE_SYSTEM=<hostname> or REMOTE_SYSTEM=<IP Address>.  This is because there is no matching entry defined in the /etc/hosts.allow and /etc/hosts.deny is configured to deny all other connections.

Resolution

Add the following line to /etc/hosts.allow file to ensure XCOM transfers are allowed to execute on this server:

xcom* : ALL

Optionally, they can also use designated partner names in place of ALL to allow XCOM connections from selected partner systems.