[Sshguard-users] sshguard 1.5 abort on startup with -b

[Jin C. <js...@al...>]

When running sshguard for the first time with the -b flag, version 1.5 aborts immediately on OS X Lion.

This is because in process_blacklisted_addresses(), the blacklist values are sent directly to fw_block_list() without checking to see that there were any addresses found. If we are running for the first time, there will be no blacklist values in the given file. fw_block_list() in ipfw.c calls ipfwmod_buildblockcommand() which has this line:
    assert(addresses[0] != NULL     /* there is at least one address to block */);

A simple fix is not to call fw_block_list unless num_blacklisted > 0.