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**support200** · 10-19-2025, 11:09 AM

You need to see if it gets any DHCP requests first. Look into /nxfilter/log/nxfilter.log. See if there's any DHCP related messages in the log files.

**support200** · 10-19-2025, 11:19 AM

Or you can run 'tail -F /nxfilter/log/nxfilter.log' while you are sending DHCP requests.

**NeXus** · 10-19-2025, 12:15 PM

Ohh WOW - thx a lot for the super fast responses!!

Here are two log infos:

1) nxfilter-LOG (Tail)

Code:

nexus6@lovepi:~ $ [B]tail -F /nxfilter/log/nxfilter.log[/B]
INFO [10-19 13:07:05] - MHMr, Stats, reqCnt = 8197, blockCnt = 0, domainCnt = 7 27, userCnt = 1, tokenNameCnt = 0, cltIpCnt = 2, malwareCnt = 0, fwdErrCnt = 0, domainTestCnt = 2, xUserCnt = 0, xIpCnt = 2, xReqCnt = 5220.
INFO [10-19 13:07:05] - MHMr, Cache size = 1619|0|0.
INFO [10-19 13:08:00] - LWf, logAll.logCnt = 1, logAll.signalCnt = 0, logAll.fl owCnt = 0, logAll.recvFlow = 0, logAll.dhcpCnt = 0, logAll.recvDhcp = 0.
INFO [10-19 13:08:05] - DSf, udpCnt = 1, tlsCnt = 0, aclDropCnt = 0, queryCnt = 1, customCnt = 0, authRediCnt = 0, authDropCnt = 0, refreshCnt = 1, pstCacheCnt = 0, respCacheHitCnt = 1, cacheHitRatio = 100%.
INFO [10-19 13:08:05] - MHMr, Stats, reqCnt = 8198, blockCnt = 0, domainCnt = 7 27, userCnt = 1, tokenNameCnt = 0, cltIpCnt = 2, malwareCnt = 0, fwdErrCnt = 0, domainTestCnt = 2, xUserCnt = 0, xIpCnt = 2, xReqCnt = 5221.
INFO [10-19 13:08:05] - MHMr, Cache size = 1619|0|0.
INFO [10-19 13:09:00] - LWf, logAll.logCnt = 4, logAll.signalCnt = 0, logAll.fl owCnt = 0, logAll.recvFlow = 0, logAll.dhcpCnt = 0, logAll.recvDhcp = 0.
INFO [10-19 13:09:05] - DSf, udpCnt = 5, tlsCnt = 0, aclDropCnt = 0, queryCnt = 5, customCnt = 0, authRediCnt = 0, authDropCnt = 0, refreshCnt = 3, pstCacheCnt = 0, respCacheHitCnt = 3, cacheHitRatio = 60%.
INFO [10-19 13:09:05] - MHMr, Stats, reqCnt = 8203, blockCnt = 0, domainCnt = 7 27, userCnt = 1, tokenNameCnt = 0, cltIpCnt = 2, malwareCnt = 0, fwdErrCnt = 0, domainTestCnt = 2, xUserCnt = 0, xIpCnt = 2, xReqCnt = 5223.
INFO [10-19 13:09:05] - MHMr, Cache size = 1619|0|0.
INFO [10-19 13:09:48] - RespCache.add, cache not added, trace-server.prod-clust ered.bugs.firebat.prime-video.amazon.dev , No answer record, queryType = 1, rcod e = 3.
INFO [10-19 13:10:00] - LWf, logAll.logCnt = 8, logAll.signalCnt = 0, logAll.fl owCnt = 0, logAll.recvFlow = 0, logAll.dhcpCnt = 0, logAll.recvDhcp = 0.
INFO [10-19 13:10:05] - DSf, udpCnt = 10, tlsCnt = 0, aclDropCnt = 0, queryCnt = 10, customCnt = 0, authRediCnt = 0, authDropCnt = 0, refreshCnt = 8, pstCacheC nt = 0, respCacheHitCnt = 8, cacheHitRatio = 80%.
INFO [10-19 13:10:05] - MHMr, Stats, reqCnt = 8213, blockCnt = 0, domainCnt = 7 27, userCnt = 1, tokenNameCnt = 0, cltIpCnt = 2, malwareCnt = 0, fwdErrCnt = 0, domainTestCnt = 2, xUserCnt = 0, xIpCnt = 2, xReqCnt = 5230.
INFO [10-19 13:10:05] - MHMr, Cache size = 1619|0|0.

2) nao nxfilter.log

Code:

nexus6@lovepi:~ $ [B]nano /nxfilter/log/nxfilter.log[/B]

 INFO [10-19 13:00:05] - MHMr, Cache size = 1608|0|0.
 INFO [10-19 13:01:00] - LWf, logAll.logCnt = 37, logAll.signalCnt = 0, logAll.>
 INFO [10-19 13:01:05] - DSf, udpCnt = 41, tlsCnt = 0, aclDropCnt = 0, queryCnt>
 INFO [10-19 13:01:05] - MHMr, Stats, reqCnt = 8136, blockCnt = 0, domainCnt = >
 INFO [10-19 13:01:05] - MHMr, Cache size = 1617|0|0.
 INFO [10-19 13:01:05] - RespCache.clearNegativeCache, Negative cache has been >
 INFO [10-19 13:01:31] - RespCache.add, cache not added, sos.epdg.epc.mnc001.mc>
 INFO [10-19 13:02:00] - LWf, logAll.logCnt = 16, logAll.signalCnt = 0, logAll.>
 INFO [10-19 13:02:05] - DSf, udpCnt = 14, tlsCnt = 0, aclDropCnt = 0, queryCnt>
 INFO [10-19 13:02:05] - MHMr, Stats, reqCnt = 8150, blockCnt = 0, domainCnt = >
 INFO [10-19 13:02:05] - MHMr, Cache size = 1617|0|0.
 INFO [10-19 13:03:00] - LWf, logAll.logCnt = 17, logAll.signalCnt = 0, logAll.>
 INFO [10-19 13:03:05] - DSf, udpCnt = 20, tlsCnt = 0, aclDropCnt = 0, queryCnt>
 INFO [10-19 13:03:05] - MHMr, Stats, reqCnt = 8170, blockCnt = 0, domainCnt = >
 INFO [10-19 13:03:05] - MHMr, Cache size = 1619|0|0.
 INFO [10-19 13:04:00] - LWf, logAll.logCnt = 4, logAll.signalCnt = 0, logAll.f>
 INFO [10-19 13:04:05] - DSf, udpCnt = 8, tlsCnt = 0, aclDropCnt = 0, queryCnt >
 INFO [10-19 13:04:05] - MHMr, Stats, reqCnt = 8178, blockCnt = 0, domainCnt = >
 INFO [10-19 13:04:05] - MHMr, Cache size = 1619|0|0.

I assume: Maybe there is no responses: There is no “DHCP Offer” (IP offered by the server) or “DHCP ACK” (confirmation) in the output. The Raspi with NX receives the requests, they are reaching NX, right?! – NXFilter should respond to this if it is configured correctly on NXFilter 255.255.255.255:67
And after a while (some attemps) my mobil device device gives up or falls back to an APIPA IP (169.254.x.x) if no DHCP server responds.

What do you guys think?

Again thanks for the help!
NeX

**support200** · 10-19-2025, 12:40 PM

You should see this kind of messages:

Code:

 INFO ({DhcpServer} DhcpServer.java[run]:170) [2025-10-19 20:37:43] - DhcpServer.run, DHCP DISCOVER, macStr = B4:8C:9D:BD:FB:05, srcIp = 192.168.0.204, hostname = java-dhcp-client5
DEBUG ({DhcpServer} IpPool.java[addLeasedIp]:111) [2025-10-19 20:37:43] - IpPool.addLeasedIp, LeasedIp{ip=192.168.0.88, mac=B4:8C:9D:BD:FB:05, hostname=java-dhcp-client5, leaseTimestamp=1760873863, leaseTimestampStr=20251019203743, expireTimestamp=1760960563, expireTimestampStr=20251020204243}
 INFO ({DhcpServer} AvaxIpList.java[printInfo]:210) [2025-10-19 20:37:43] - AvaxList.printInfo, leasedList.size() = 40, ip2leased.size = 40, mac2leased.size = 4, curIdx = 2.
 INFO ({DhcpServer} IpPool.java[getUnleasedIp]:140) [2025-10-19 20:37:43] - IpPool.getUnleasedIp, Found a reserved IP = 192.168.0.88, MAC = B4:8C:9D:BD:FB:05, hostname = java-dhcp-client5.
 INFO ({DhcpServer} DhcpServer.java[run]:229) [2025-10-19 20:37:43] - DhcpServer.run, IP lease 192.168.0.88 → B4:8C:9D:BD:FB:05

You may need to rum some kind of packet capture tool in the same system to see the actual DHCP discover packets going to NxFilter.

**NeXus** · 10-19-2025, 02:49 PM

Thx for the positive example! Yes, that is basically whats not happening... :-(
I have no other running DHCP-Servers, the ports are free, i.e., not double-occupied, the installation, including permissions, is correct, and network traffic is also running!
To ensure that communication between each client and Nx is working, I simply sent "test (4 bytes). Result w..u. = The bytes arrived correctly!

Code:

[B]LAN-Client (192.168.178.7)[/B]
root@lovecloud:~#[B] echo -n "test" | nc -u 192.168.178.9 67[/B]


[B]NxFilter on RasPi (192.168.178.9)[/B]
nexus6@lovepi:~ $[B] sudo tcpdump -i eth0 port 67 or port 68 -n -v[/B]

tcpdump: listening on eth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
15:45:38.922032 IP (tos 0x0, ttl 64, id 4551, offset 0, flags [DF], proto UDP (17), length 32)
    192.168.178.7.51281 > 192.168.178.9.67: BOOTP/DHCP, unknown (0x74), length 4 [|bootp]
^C
1 packet captured
1 packet received by filter
0 packets dropped by kernel

Reinstalled everything, startI deleted everything, reinstalled, reconfigured...but the error remains!

**NeXus** · 10-19-2025, 03:54 PM

Hi & sorry for kinda spaming here, bute I did another test.

I simply tried another DHCP server (isc-dhcp-server) on a trial basis, and with the following settings, the DHCP takeover worked immediately and without any problems after switching off the DHCP server on the FritzBox!

So I conclude: I have no "direct" configuration problem, but a config problem with the DHCP-settings of NxFilter!

Code:

# /etc/dhcp/dhcpd.conf für isc-dhcp-server auf Raspberry Pi
authoritative;
ddns-update-style none;
deny duplicates;

default-lease-time 600;
max-lease-time 3600;

host pixel9 {
    hardware ethernet de:33:71:10:6a:01;
    fixed-address 192.168.178.202;
}
host repeater1 {
    hardware ethernet d4:d4:da:7b:f0:9c;
    fixed-address 192.168.178.100;
}

subnet 192.168.178.0 netmask 255.255.255.0 {
    range 192.168.178.200 192.168.178.240;
    option subnet-mask 255.255.255.0;
    option broadcast-address 192.168.178.255;
    option routers 192.168.178.1;
    option domain-name-servers 192.168.178.9, 8.8.8.8;
    option domain-name "local";
}

nexus6@lovepi:/ $ sudo systemctl start isc-dhcp-server

**support200** · 10-20-2025, 12:29 AM

Show me /nxfilter/conf/dhcp.properties file and then restart NxFilter and then show me /nxfilter/nxfilter.log file. If you don't want to post them here, you can send me those files at support@nxfilter.org.

**NeXus** · 10-20-2025, 09:48 AM

Hi! Here is my

/nxfilter/conf/dhcp.properties

Code:

[HASHTAG="t105"]dhcp[/HASHTAG] Configuration
#Mon Oct 20 10:46:18 CEST 2025
boot_file=
default_domain=
dns_ip=192.168.178.9
end_ip=192.168.178.240
gateway_ip=192.168.178.1
lease_seconds=86400
listen_ip=192.168.178.9
max_pool_size=20000
ntp_ip=
prevent_conflict=0
run_dhcp=0
start_ip=192.168.178.20
subnet_mask=255.255.255.0
tftp_server=
wpad_url=

**support200** · 10-20-2025, 09:56 AM

run_dhcp=0 means that you disabled the DHCP service. Did you disable it?

Stop NxFilter and set run_dhcp=1 in the file and then start NxFilter and then send me /nxiflter/log/nxfilter.log or post it here.

**NeXus** · 10-20-2025, 12:13 PM

Hi!
Yes, I disabled the DHCP for now and enabled the FritzBox DHCP service.
Here we go:

tail -F /nxfilter/log/nxfilter.log

Code:

nexus6@lovepi:~ $ tail -F /nxfilter/log/nxfilter.log
 INFO [10-20 13:10:16] - RMcR, Adding a upstream resolver : SimpleResolver [/8.8.8.8:53].
 INFO [10-20 13:10:16] - NxResolver.NxResolver, DoH URI template = https://cloudflare-dns.com/dns-query
 INFO [10-20 13:10:16] - MM, RequestHandler started.
 INFO [10-20 13:10:16] - MM, UdpServer started.
 INFO [10-20 13:10:16] - MM, Starting TCP DB.
 INFO [10-20 13:10:16] - MM, DHCP starter started.
 INFO [10-20 13:10:16] - MM, Starting Tomcat.
 INFO [10-20 13:10:16] - DhcpStarter.startServer, DhcpServer started.
 INFO [10-20 13:10:16] - DhcpServer.run, DHCP server running on port 67
 INFO [10-20 13:10:16] - DhcpStarter.run, Current DHCP Setup, DhcpSetup{listenIp=192.168.178.9, startIp=192.168.178.20, endIp=192.168.178.240, subnetMask=255.255.255.0, gatewayIp=192.168.178.1, dnsIps=[192.168.178.9], leaseSeconds=86400, tftpServer=, bootFile=, maxPoolSize=20000, ntpIps=[], wpadUrl=, runDhcp=true, secondaryFlag=false, preventConflict=false}
 INFO [10-20 13:10:17] - HandyMan.setBlockPublicIp, cfg.blockPublicIp has been set to 87.177.159.174.
 INFO [10-20 13:10:17] - Main.HandyMan.deleteOld, Started.
 INFO [10-20 13:10:18] - MHMrU, Doing remote update for Jahaslist.
 INFO [10-20 13:10:18] - JahasUpdate.remoteRecatOne, Processing /nxfilter/tmp/repository_jahastech_com__jahaslist_random_jsp/random_jsp
 INFO [10-20 13:10:19] - JahasUpdate.remoteRecatOne, oldVer = 102905, newVer = 102905.
 INFO [10-20 13:10:19] - JahasUpdate.remoteRecatOne, Nothing to update.
 INFO [10-20 13:10:19] - MHMrU, Jahaslist has been updated.
 INFO [10-20 13:10:27] - NxClassifier.addQueue, Domain added. - sos.epdg.epc.mnc001.mcc262.pub.3gppnetwork.org, domainQueue.size() = 1.
 INFO [10-20 13:10:27] - NxClassifier.run, MyClassifier - 0, Started working on sos.epdg.epc.mnc001.mcc262.pub.3gppnetwork.org.
 INFO [10-20 13:10:27] - RespCache.add, cache not added, sos.epdg.epc.mnc001.mcc262.pub.3gppnetwork.org , No answer record, queryType = 1, rcode = 3.
 INFO [10-20 13:10:27] - NxClassifier.run, MyClassifier - 0, Domain not exist! - sos.epdg.epc.mnc001.mcc262.pub.3gppnetwork.org.
 INFO [10-20 13:10:32] - NxClassifier.addQueue, Domain added. - eu.roaming.svc.cloud.microsoft, domainQueue.size() = 1.
 INFO [10-20 13:10:32] - NxClassifier.run, MyClassifier - 0, Started working on eu.roaming.svc.cloud.microsoft.
 INFO [10-20 13:10:35] - NxClassifier._scanDomain, URL = http://eu.roaming.svc.cloud.microsoft
 INFO [10-20 13:10:35] - NxClassifier._scanDomain, java.net.SocketTimeoutException: Connect timed out
 INFO [10-20 13:10:35] - LCcRC, licCnt = 0, historyCnt = 175, trafficCnt = 1073, maxCnt = 40000000.
 INFO [10-20 13:10:35] - LCcRC, historyCnt bigger than licCnt.
 INFO [10-20 13:10:35] - RMcR, Resolving DNS server : [1.1.1.1, 8.8.4.4, 8.8.8.8]
 INFO [10-20 13:10:35] - RMcR, Adding a upstream resolver : SimpleResolver [/1.1.1.1:53].
 INFO [10-20 13:10:35] - RMcR, Adding a upstream resolver : SimpleResolver [/8.8.4.4:53].
 INFO [10-20 13:10:35] - RMcR, Adding a upstream resolver : SimpleResolver [/8.8.8.8:53].
 INFO [10-20 13:10:35] - RHiAD, System block, dns.google.
 INFO [10-20 13:11:01] - LWf, logAll.logCnt = 26, logAll.signalCnt = 0, logAll.flowCnt = 0, logAll.recvFlow = 0, logAll.dhcpCnt = 0, logAll.recvDhcp = 0.
 INFO [10-20 13:11:04] - NxClassifier.addQueue, Domain added. - 10000.mt.eu.iot.dreame.tech, domainQueue.size() = 1.
 INFO [10-20 13:11:04] - NxClassifier.run, MyClassifier - 0, Started working on 10000.mt.eu.iot.dreame.tech.
 INFO [10-20 13:11:07] - NxClassifier._scanDomain, URL = http://10000.mt.eu.iot.dreame.tech
 INFO [10-20 13:11:07] - NxClassifier._scanDomain, java.net.SocketTimeoutException: Connect timed out
^C
nexus6@lovepi:~ $

**support200** · 10-20-2025, 12:33 PM

The DHCP service has been started.

--
INFO [10-20 13:10:16] - DhcpStarter.startServer, DhcpServer started.
INFO [10-20 13:10:16] - DhcpServer.run, DHCP server running on port 67
--

Can you send some DHCP packets? You can download a Windows client tester here: https://github.com/CyberShadow/dhcpt...readme-ov-file

Use it like: dhcptest-0.9-win64.exe --target 192.168.0.103

192.168.0.103 is my NxFilter IP. When it starts, tyep 'd'.

Code:

Listening for DHCP replies on port 68.
Type "d" to broadcast a DHCP discover packet, or "help" for details.
d
Sending packet:
  op=BOOTREQUEST chaddr=2E:B8:7F:42:4C:C8 hops=0 xid=6995D0EB secs=0 flags=8000
  ciaddr=0.0.0.0 yiaddr=0.0.0.0 siaddr=0.0.0.0 giaddr=0.0.0.0 sname= file=
  1 options:
     53 (DHCP Message Type): discover
Received packet from 192.168.0.103:67:
  op=BOOTREPLY chaddr=2E:B8:7F:42:4C:C8 hops=0 xid=6995D0EB secs=0 flags=8000
  ciaddr=0.0.0.0 yiaddr=192.168.0.56 siaddr=0.0.0.0 giaddr=0.0.0.0 sname= file=
  6 options:
     53 (DHCP Message Type): offer
     54 (Server Identifier): 192.168.0.103
     51 (IP Address Lease Time): 86400 (1 day)
      1 (Subnet Mask): 255.255.255.0
      3 (Router Option): 192.168.0.1
      6 (Domain Name Server Option): 8.8.8.8

**NeXus** · 10-20-2025, 05:49 PM

All righty then! For reference I analysed the working DHCP on the FritzBox (192.168.178.1) and then after that the NXFilter on 192.168.178.1.
But then I realized that I am using the Win-Client that is connected via IP from FritzBox and I cant re-connect with new IP from NXFilter because I would loose connection...

So that result doesnt say much, right!?

I wish I had that tool for Linux! Will look around for another similar cmd-line thingy for Linux.

[/CODE]
^C
C:\>dhcptest-0.9-win64.exe --target 192.168.178.1
dhcptest v0.9 - Created by Vladimir Panteleev
https://github.com/CyberShadow/dhcptest
Run with --help for a list of command-line options.

Listening for DHCP replies on port 68.
Type "d" to broadcast a DHCP discover packet, or "help" for details.
d
Sending packet:
op=BOOTREQUEST chaddr=42:EC:44:C2:51:8D hops=0 xid=58581B67 secs=0 flags=8000
ciaddr=0.0.0.0 yiaddr=0.0.0.0 siaddr=0.0.0.0 giaddr=0.0.0.0 sname= file=
1 options:
53 (DHCP Message Type): discover
Received packet from 192.168.178.1:67:
op=BOOTREPLY chaddr=42:EC:44:C2:51:8D hops=0 xid=58581B67 secs=0 flags=8000
ciaddr=0.0.0.0 yiaddr=192.168.178.21 siaddr=192.168.178.1 giaddr=0.0.0.0 sname= file=
13 options:
53 (DHCP Message Type): offer
54 (Server Identifier): 192.168.178.1
51 (IP Address Lease Time): 604800 (1 week)
58 (Renewal (T1) Time Value): 302400 (3 days and 12 hours)
59 (Rebinding (T2) Time Value): 529200 (6 days and 3 hours)
1 (Subnet Mask): 255.255.255.0
3 (Router Option): 192.168.178.1
6 (Domain Name Server Option): 192.168.178.1
15 (Domain Name): fritz.box
26 (Interface MTU Option): 1500
28 (Broadcast Address Option): 192.168.178.255
42 (Network Time Protocol Servers Option): 192.168.178.1
158 (Unknown): ^C
C:\>dhcptest-0.9-win64.exe --target 192.168.178.9
dhcptest v0.9 - Created by Vladimir Panteleev
https://github.com/CyberShadow/dhcptest
Run with --help for a list of command-line options.

Listening for DHCP replies on port 68.
Type "d" to broadcast a DHCP discover packet, or "help" for details.
d
Sending packet:
op=BOOTREQUEST chaddr=E6:C5:1E:B2:85:49 hops=0 xid=92B5DBCE secs=0 flags=8000
ciaddr=0.0.0.0 yiaddr=0.0.0.0 siaddr=0.0.0.0 giaddr=0.0.0.0 sname= file=
1 options:
53 (DHCP Message Type): discover
Received packet from 192.168.178.9:67:
op=BOOTREPLY chaddr=E6:C5:1E:B2:85:49 hops=0 xid=92B5DBCE secs=0 flags=8000
ciaddr=0.0.0.0 yiaddr=192.168.178.21 siaddr=0.0.0.0 giaddr=0.0.0.0 sname= file=
6 options:
53 (DHCP Message Type): offer
54 (Server Identifier): 192.168.178.9
51 (IP Address Lease Time): 86400 (1 day)
1 (Subnet Mask): 255.255.255.0
3 (Router Option): 192.168.178.1
6 (Domain Name Server Option): 192.168.178.9
Error on listening thread:
^C
C:\>
[CODE]

**support200** · 10-20-2025, 10:16 PM

The test method I suggested is the simpleste one. This broadcast packet can have other kinds of problems. So, we recommended you to test it with the unicast way first. We do the test by Windows, Linux, Android and iPad and others. Anyway, you knew that how it works when it gets a DHCP request packet. So, what you need to find out is why it doesn't get the DHCP packet in your network.

**NeXus** · 10-21-2025, 12:54 PM

Thank you very much for your help and support, but I'm giving up now.

I was looking for an out-of-the-box solution, but I have to invest so much time in this, especially since other DHCP servers work right away.

Thanks again, for ne this topic/post is closed.

Announcement

DHCP not working with FritzBox!?

DHCP not working with FritzBox!?

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