Description
Uplog is an UDP based ping program that gives an ASCII-graphical log
of the packet losses.
Once a second uplog sends a packet to the echo port (7) of the target host and waits for a reply. If it gets a reply a X is written, otherwise a dot (.) is written to the log file. If a packet with a wrong sequence number arrives a colon (:) is written to the log file.

By examining the log file one can easily see when and how the packet losses occur. For instance the pattern below with 5 second sections of total packet loss suggests that there's some kind of routing problem caused by routing flaps.

2003-06-13 08:47 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-13 08:48 XXXXXXXXXXXXXXXXXXXXXXXXX.....XXXXX.....XXXXXXXXXXXXXXXXXXXX
2003-06-13 08:49 XXXXXXX.....XXXXX.....XXXXX...XXXXXXX.....XXXXXXXXXXXXXX....
2003-06-13 08:50 .XXXXX.....XXXXXXXXXXXXXXXXXXXXXXXXXXX.....XXXXX.....XXXXX..
2003-06-13 08:51 ...XXXXXXXXXXXXXXXXXX.....XXXXX.....XXXXXXXXXXXXXX......XXXX
2003-06-13 08:52 X.....XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-13 08:53 XXXXXXXXXXXXXXXXXXXXXXXXXX....XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Or just that the network is slightly overloaded during peak hours as below.

2003-06-09 14:00 XXXXXXXXXXXXX.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-09 14:01 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-09 14:02 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-09 14:03 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.XXXXXXXXXXX
2003-06-09 14:04 XXXXXXXXXXXXXXXXXX.XXX.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-09 14:05 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.XXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-09 14:06 XXXXXXXXXXXX.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2003-06-09 14:07 XXXXXXXXXXXXXXXXXXX.XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

The program runs by default as a daemon and writes the log to a file, but it can be used as a foreground process that prints to stdout instead.

Download
2008-01-09 Version 0.3  uplog-0.3.tar.gz
2003-06-18 Version 0.2  uplog-0.2.tar.gz
2003-06-15 Version 0.1  uplog-0.1.tar.gz

History
2008-01-09 Version 0.3
    Added option for changing packet size
2003-06-18 Version 0.2
    Support for Solaris and Darwin
2003-06-15 Version 0.1
    Initial release