While experimenting with my new dvmega, mmdvmhost and ircddbgatewayd, I saw opening and closing sessions to ircddb hosts (tcp port 9007). ircddbgatewayd from git head is self-compiled.
With tcpdump -ni eth0 -X -s 2048 tcp port 9007, I observed the following:

===
11:13:44.779039 IP 192.168.1.103.36273 > 216.155.157.11.9007: Flags [P.], seq 19:83, ack 216, win 473, options [nop,nop,TS val 26308155 ecr 60428599]
, length 64
0x0000: 4500 0074 5457 4000 4006 ae76 c0a8 0167 E..tTW@[email protected]
0x0010: d89b 9d0b 8db1 232f b640 3f41 3701 7f0d ......#/.@?A7...
0x0020: 8018 01d9 381d 0000 0101 080a 0191 6e3b ....8.........n;
0x0030: 039a 1137 5553 4552 2020 3020 2a20 3a43 ...7USER..0..:C
0x0040: 4952 4344 4442 3a31 2e32 2e34 206c 696e IRCDDB:1.2.4.lin
0x0050: 7578 5f69 7263 6464 6267 6174 6577 6179 ux_ircddbgateway
0x0060: 642d 3230 3136 3031 3331 202d 2044 4542 d-20160131.-.DEB
0x0070: 5547 0d0a UG..
11:13:45.284900 IP 216.155.157.11.9007 > 192.168.1.103.36273: Flags [P.], seq 216:276, ack 83, win 29, options [nop,nop,TS val 60433106 ecr 26308155], length 60
0x0000: 4528 0070 77c5 4000 3106 99e4 d89b 9d0b E([email protected].......
0x0010: c0a8 0167 232f 8db1 3701 7f0d b640 3f81 ...g#/..7....@?.
0x0020: 8018 001d 3e92 0000 0101 080a 039a 22d2 ....>.........".
0x0030: 0191 6e3b 3a32 3136 2e31 3535 2e31 3537 ..n;:216.155.157
0x0040: 2e31 3120 3436 3120 3232 3241 4141 344b .11.461.222AAA4K
0x0050: 5420 5553 4552 203a 4e6f 7420 656e 6f75 T.USER.:Not.enou
0x0060: 6768 2070 6172 616d 6574 6572 732e 0d0a gh.parameters...
..
11:14:18.764611 IP 216.155.157.11.9007 > 192.168.1.103.50828: Flags [P.], seq 1:162, ack 1, win 29, options [nop,nop,TS val 60466721 ecr 26311516], l
ength 161
0x0000: 4528 00d5 b849 4000 3106 58fb d89b 9d0b E([email protected].....
0x0010: c0a8 0167 232f c68c 1e66 1e68 5ad3 e14b ...g#/...f.hZ..K
0x0020: 8018 001d 94b4 0000 0101 080a 039a a621 ...............!
0x0030: 0191 7b5c 3a32 3136 2e31 3535 2e31 3537 ..{:216.155.157
0x0040: 2e31 3120 4e4f 5449 4345 2041 7574 6820 .11.NOTICE.Auth.
0x0050: 3a2a 2a2a 204c 6f6f 6b69 6e67 2075 7020 :.Looking.up.
0x0060: 796f 7572 2068 6f73 746e 616d 652e 2e2e your.hostname...
0x0070: 0d0a 3a32 3136 2e31 3535 2e31 3537 2e31 ..:216.155.157.1
0x0080: 3120 4e4f 5449 4345 2032 3232 4141 4134 1.NOTICE.222AAA4
0x0090: 4c4c 203a 2a2a 2a20 536b 6970 7069 6e67 LL.:*.Skipping
0x00a0: 2068 6f73 7420 7265 736f 6c75 7469 6f6e .host.resolution
0x00b0: 2028 6469 7361 626c 6564 2062 7920 7365 .(disabled.by.se
0x00c0: 7276 6572 2061 646d 696e 6973 7472 6174 rver.administrat
0x00d0: 6f72 290d 0a or)..
..
11:14:19.501800 IP 192.168.1.103.50828 > 216.155.157.11.9007: Flags [P.], seq 1:9, ack 162, win 473, options [nop,nop,TS val 26311628 ecr 60466721], length 8
0x0000: 4500 003c 9a7f 4000 4006 6886 c0a8 0167 E..<..@[email protected]....g
0x0010: d89b 9d0b c68c 232f 5ad3 e14b 1e66 1f09 ......#/Z..K.f..
0x0020: 8018 01d9 37e5 0000 0101 080a 0191 7bcc ....7.........{.
0x0030: 039a a621 5041 5353 203a 0d0a ...!PASS.:..
..
11:14:19.936753 IP 192.168.1.103.50828 > 216.155.157.11.9007: Flags [P.], seq 9:19, ack 162, win 473, options [nop,nop,TS val 26311671 ecr 60467836], length 10
0x0000: 4500 003e 9a80 4000 4006 6883 c0a8 0167 E..>..@[email protected]....g
0x0010: d89b 9d0b c68c 232f 5ad3 e153 1e66 1f09 ......#/Z..S.f..
0x0020: 8018 01d9 37e7 0000 0101 080a 0191 7bf7 ....7.........{.
0x0030: 039a aa7c 4e49 434b 203a 2d33 0d0a ...|NICK.:-3..
..
11:14:20.416423 IP 216.155.157.11.9007 > 192.168.1.103.50828: Flags [P.], seq 162:216, ack 19, win 29, options [nop,nop,TS val 60468284 ecr 26311671], length 54
0x0000: 4528 006a b84c 4000 3106 5963 d89b 9d0b E([email protected]....
0x0010: c0a8 0167 232f c68c 1e66 1f09 5ad3 e15d ...g#/...f..Z..]
0x0020: 8018 001d 9f03 0000 0101 080a 039a ac3c ...............<
0x0030: 0191 7bf7 3a32 3136 2e31 3535 2e31 3537 ..{.:216.155.157
0x0040: 2e31 3120 3433 3220 3232 3241 4141 344c .11.432.222AAA4L
0x0050: 4c20 2d33 203a 4572 726f 6e65 6f75 7320 L.-3.:Erroneous.
0x0060: 4e69 636b 6e61 6d65 0d0a Nickname..
..

Enabling and disabling ircddbEnabled=1 or 0 had no effect. And even when ircddbHostname left blank, I saw after restart new connections with the same effect.
Even if configured ircddbEnabled=1 with ircddbHostname=rr.openquad.net , and functional login (tcpdump showed irc channel messages), I saw new connection retries with invalid username.

My fault:
I striped down my configuration file, without unneeded settins like
repeaterBand2= , repeaterBand3=, repeaterBand4 , without starNetBand..., and without ircddbEnabled2= , ircddbEnabled3= , ircddbEnabled4 settings.

I assumed, there must be something been hardcoded.

Here, I see

find . -type f -exec grep -H DEFAULT_IRCDDB_HOSTNAME '{}' ';'

./ircDDBGateway/Common/IRCDDBGatewayConfig.cpp:const wxString DEFAULT_IRCDDB_HOSTNAME = wxT("group1-irc.ircddb.net");
./ircDDBGateway/Common/IRCDDBGatewayConfig.cpp:const wxString DEFAULT_IRCDDB_HOSTNAME2 = wxT("rr.openquad.net");
./ircDDBGateway/Common/IRCDDBGatewayConfig.cpp:const wxString DEFAULT_IRCDDB_HOSTNAME3 = wxEmptyString;
./ircDDBGateway/Common/IRCDDBGatewayConfig.cpp:const wxString DEFAULT_IRCDDB_HOSTNAME4 = wxEmptyString;

Ok, IRCDDBGatewayConfig.cpp is part of the configuration program.
Anyway, after setting
ircddbEnabled2=0
ircddbHostname2=
ircddbUsername2=
ircddbPassword2=
the buggy connection attempts stoped.

It seems, there was a default for ircddbHostname2, and ircddbEnabled2 was by default enabled.

In addidtion, I also added
ircddbEnabled3=0
ircddbHostname3=
ircddbUsername3=
ircddbPassword3=
ircddbEnabled4=0
ircddbHostname4=
ircddbUsername4=
ircddbPassword4=
..just 4 case ;)