dhcp-relay over tun interface - solution?

[Shane Kerr]

Stefan,

On 2014-01-15 18:02:08 (+0100)
Stefan Bauer <stefan.bauer at cubewerk.de> wrote:

socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 4
bind(4, {sa_family=AF_INET, sin_port=htons(67), sin_addr=inet_addr("0.0.0.0")}, 16) = 0
socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 5
bind(5, {sa_family=AF_INET, sin_port=htons(67), sin_addr=inet_addr("0.0.0.0")}, 16) = 0
sendto(4, "\1\1\6\1]\370\223*\f\0\200\0\0\0\0\0\0\0\0\0\0\0\0\0S6\317\376\0\20\30\250"..., 260, 0, {sa_family=AF_INET, sin_port=htons(67), sin_addr=inet_addr("1.2.3.4")}, 16) = 260
sendto(4, "\1\1\6\1\374\243\312\"\34\0\200\0\0\0\0\0\0\0\0\0\0\0\0\0S6\317\376\0\20\30\250"..., 260, 0, {sa_family=AF_INET, sin_port=htons(67), sin_addr=inet_addr("1.2.3.4")}, 16) = 260
sendto(4, "\1\1\6\1\374\243\312\"\34\0\200\0\0\0\0\0\0\0\0\0\0\0\0\0S6\317\376\0\20\30\250"..., 260, 0, {sa_family=AF_INET, sin_port=htons(67), sin_addr=inet_addr("1.2.3.4")}, 16) = 260
sendto(4, "\1\1\6\1\374\243\312\"\34\0\200\0\0\0\0\0\0\0\0\0\0\0\0\0S6\317\376\0\20\30\250"..., 260, 0, {sa_family=AF_INET, sin_port=htons(67), sin_addr=inet_addr("1.2.3.4")}, 16) = 260
--- SIGINT (Interrupt) @ 0 (0)

Well it looks like everything is being sent properly. My guess would be
that this is a routing problem, or perhaps some horrible firewall issue.

Can you ping 1.2.3.4 properly?

My theory is that packets to 1.2.3.4 are going out over eth0 and not
your tunnel. We could see that by checking for these via:

root at test:~# tcpdump -ni eth0 port 67 or 68

If these are indeed going out over eth0 and not tuntest then there is
something wrong with your networking setup, and fixing that should sort
you out.

Cheers,

--
Shane