25: Configuring DHCP forwarding
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© Virtual Access 2018
GW2020 Series User Manual
Issue: 2.1
Page 252 of 423
25.4.3.2
Source NAT for DHCP forwarding over IPSec using package options
root@VA_router:~# uci export firewall
package firewall
……
config redirect
option target 'SNAT'
option src 'lan'
option dest 'wan'
option src_dip '192.168.100.1'
option name 'DHCPMessages'
option proto 'udp'
option dest_port '67'
25.5
DHCP forwarding diagnostics
25.5.1
Tracing DHCP packets
To trace DHCP packets on any interface on the router, enter tcpdump -i any -n -p port
67 &
root@VA_router:~# tcpdump -i any -n -p port 67 &
root@VA_router:~# tcpdump: verbose output suppressed, use -v or -vv for
full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535
bytes
16:39:20.666070 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request
from 00:e0:c8:13:02:3d, length 360
16:39:20.666166 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request
from 00:e0:c8:13:02:3d, length 360
To trace stop tracing enter fg (to bring tracing task to foregraound), and then <CTRL-
C> to stop the trace.
root@VA_router:~# fg
tcpdump -i any -n -p port 67
^C
33 packets captured
33 packets received by filter
0 packets dropped by kernel