Hello Ray,

I used the attached patch to fix the problem:
--- a/src/dhcp.c        2016-10-26 20:29:04.756059875 +0200
+++ b/src/dhcp.c        2016-10-26 20:27:57.793515090 +0200
@@ -420,6 +420,11 @@ void dhcp_packet(time_t now, int pxe_fd)
           if (ioctl(daemon->dhcpfd, SIOCSARP, &arp_req) == -1)
             my_syslog(MS_DHCP | LOG_ERR, _("ARP-cache injection failed: %s"), 
strerror(errno));
         }
+       /* This is a reply that is to be relayed, unset target interface
+       to enforce routing. */
+       if (is_relay_reply) {
+               pkt->ipi_ifindex = 0;
+       }
     }
 #elif defined(HAVE_SOLARIS_NETWORK)
   else if ((ntohs(mess->flags) & 0x8000) || mess->hlen != ETHER_ADDR_LEN || 
mess->htype != ARPHRD_ETHER)

I sent it to the mailinglist, but there was no interest in it. Please try and 
inform me.

Kind regards,

André


Am 15.09.2017 um 02:26 schrieb Ray Ramadorai:
> I recently was trying to transition from OpenWRT to LEDE and ran into a 
> problem with DHCP relay not working correctly after the transition.  I have 
> taken debug about as far as I can and am looking for some help going forward. 
> 
>  
> 
> Some details on network and configuration:
> 
>  
> 
> Network A (VLAN82) 192.168.42.0/24
> 
>                 Host: DHCP Server 192.168.42.4
> 
>                 Host: Relay 192.168.42.41 on interface (eth0.82)
> 
>  
> 
> Network B (VLAN85) 192.168.85.0/24
> 
>                 Host: DHCP Client MAC:  (00:0c:29:ed:03:a5)
> 
>                 Host: Relay 192.168.85.2 on interface (eth0.85)
> 
>  
> 
> dnsmasq.conf on the Relay host:
> 
>  
> 
> dhcp-authoritative
> 
> domain-needed
> 
> localise-queries
> 
> read-ethers
> 
> bogus-priv
> 
> expand-hosts
> 
> local-service
> 
> domain=lan
> 
> server=/lan/
> 
> dhcp-leasefile=/tmp/dhcp.leases
> 
> resolv-file=/tmp/resolv.conf.auto
> 
> stop-dns-rebind
> 
> rebind-localhost-ok
> 
> dhcp-broadcast=tag:needs-broadcast
> 
> addn-hosts=/tmp/hosts
> 
> conf-dir=/tmp/dnsmasq.d
> 
> user=dnsmasq
> 
> group=dnsmasq
> 
> dhcp-relay=192.168.85.2,192.168.42.4
> 
>  
> 
> The platform is a set of virtual machines running on x86 hardware. 
> 
>  
> 
> Software versions working case:
> 
> Kernel:  Linux Openwrt 3.18.23 #1 SMP Sun Jan 31 15:32:38 CET 2016 x86_64 
> GNU/Linux
> 
> DNSMasq:  Dnsmasq version 2.73  Copyright (c) 2000-2015 Simon Kelley
> 
> Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP no-DHCPv6 
> no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC loop-detect inotify
> 
>  
> 
> Software versions NOT working case:
> 
> Kernel:  Linux LEDE 4.4.71 #0 SMP Wed Jun 7 19:24:41 2017 x86_64 GNU/Linux
> 
> Dnsmasq version 2.77  Copyright (c) 2000-2016 Simon Kelley
> 
> Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP no-DHCPv6 
> no-Lua TFTP no-conntrack no-ipset no-auth no-DNSSEC no-ID loop-detect inotify
> 
>  
> 
> In the working case the normal 4 packet DHCP handshake occurs as expected and 
> the relay passes the packets between the DHCP server and the client. 
> 
>  
> 
> In the failing case the client request packet gets from the client to the 
> relay and then on to the dhcp server via the relay.  The response from the 
> dhcp server makes it back to the relay, but then the corresponding packet 
> from the relay to the client never gets sent.  Though I see the packet come 
> back from the server it is not clear that DNSMasq sees the packet.  I can 
> attach TCP dumps as needed.   Any help in further debug steps to determine if 
> dnsmasq is not seeing the response from the DHCP server or is not sending the 
> packet and why would be very helpful. 
> 
>  
> 
> I also came across this bug that looks similar but I am not sure has been 
> reported upstream:
> 
>  
> 
> https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1686192
> 
>  
> 
>  
> 
> Thanks
> 
>  
> 
> Ray Ramadorai
> 
>  
> 
> 
> 
> _______________________________________________
> Dnsmasq-discuss mailing list
> Dnsmasq-discuss@lists.thekelleys.org.uk
> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature

_______________________________________________
Dnsmasq-discuss mailing list
Dnsmasq-discuss@lists.thekelleys.org.uk
http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss

Reply via email to