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David_Herselman
Collaborator

DHCP relay via 2nd firewall not working

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We configured central DHCP relaying, using new services, by following SK104114 and it works perfectly if we are relaying locally  (receiving DHCP broadcasts on a locally attached VLAN and sending unicast queries to the DHCP servers).

We've however deployed a second firewall and the firewall that is local to the DHCP server drops the packet although the policy matches with 'Allow'.

 

My artwork:

dhcp_relay_via_two_firewalls.png

Policy:

dhcp_relay_check_point_policy.png

 

Debug information:

fw ctl zdebug -T -e "accept host (10.150.50.1) and host(192.168.141.220) and port(67);" -m fw + vm drop


[-- Stateful VM inbound: Entering (1596318170) --];
@;1931295932; 1Aug2020 23:42:51.041041;[cpu_7];[fw4_0];Before VM: <dir 0, 192.168.141.220:67 -> 10.150.50.1:67 IPP 17> (len=337) (ifn=23) (first seen) (looked up) ;
@;1931295932; 1Aug2020 23:42:51.041044;[cpu_7];[fw4_0];fw_filter_chain: fwconn_chain_conn_exists returned 1 (conn=<dir 0, 192.168.141.220:67 -> 10.150.50.1:67 IPP 17>, is new 0), chain 0xffffc2005afc5bc8;
@;1931295932; 1Aug2020 23:42:51.041046;[cpu_7];[fw4_0];fw_cluster_ttl_anti_spoofing: conn=<dir 0, 192.168.141.220:67 -> 10.150.50.1:67 IPP 17>;
@;1931295932; 1Aug2020 23:42:51.041049;[cpu_7];[fw4_0];fw_conn_post_inspect: Packet accepted (fast path);
@;1931295932; 1Aug2020 23:42:51.041049;[cpu_7];[fw4_0];fw_filter_chain: Final switch, action=ACCEPT;
@;1931295932; 1Aug2020 23:42:51.041050;[cpu_7];[fw4_0];fw_filter_chain: packet accepted;
@;1931295932; 1Aug2020 23:42:51.041052;[cpu_7];[fw4_0];After VM: <dir 0, 192.168.141.220:67 -> 10.150.50.1:67 IPP 17> (len=337) ;
@;1931295932; 1Aug2020 23:42:51.041052;[cpu_7];[fw4_0];VM Final action=ACCEPT;
@;1931295932; 1Aug2020 23:42:51.041052;[cpu_7];[fw4_0]; ----- Stateful VM inbound Completed -----
;
@;1931295932; 1Aug2020 23:42:51.041054;[cpu_7];[fw4_0];
[-- Stateful POST VM inbound: Entering (1596318170) --];
@;1931295932; 1Aug2020 23:42:51.041055;[cpu_7];[fw4_0];fw_post_vm_chain_handler: (first_seen 32, new_conn 0, is_my_ip 0, is_first_packet 0);
@;1931295932; 1Aug2020 23:42:51.041057;[cpu_7];[fw4_0];Before POST VM: <dir 0, 192.168.141.220:67 -> 10.150.50.1:67 IPP 17> (len=337) (ifn=23) (first seen) (looked up) ;
@;1931295932; 1Aug2020 23:42:51.041058;[cpu_7];[fw4_0];fw_post_vm_chain_handler: executing handler function dhcp_reply_code;
@;1931295932; 1Aug2020 23:42:51.041064;[cpu_7];[fw4_0];fw_post_vm_chain_handler: handler function returned action DROP;
@;1931295932; 1Aug2020 23:42:51.041066;[cpu_7];[fw4_0];fw_log_drop_ex: Packet proto=17 192.168.141.220:67 -> 10.150.50.1:67 dropped by fw_post_vm_chain_handler Reason: Handler 'dhcp_reply_code' drop;
@;1931295932; 1Aug2020 23:42:51.041068;[cpu_7];[fw4_0];After POST VM: <dir 0, 192.168.141.220:67 -> 10.150.50.1:67 IPP 17> (len=337) ;
@;1931295932; 1Aug2020 23:42:51.041068;[cpu_7];[fw4_0];POST VM Final action=DROP;
@;1931295932; 1Aug2020 23:42:51.041069;[cpu_7];[fw4_0]; ----- Stateful POST VM inbound Completed -----
;

 

fw monitor -TP -e "accept dport=67 and host(10.150.50.1) and host(192.168.141.220);" -p all
in chain (23):
0: -7fffffff (0000000000000000) (00000000) SecureXL inbound (sxl_in)
1: -7ffffffe (0000000000000000) (00000000) SecureXL inbound CT (sxl_ct)
2: -7ffffff0 (ffffffff89bb93f0) (00000001) tcpt inbound (tcp_tun)
3: -7f800000 (ffffffff8a3db810) (ffffffff) IP Options Strip (in) (ipopt_strip)
4: -7d000000 (ffffffff89bda870) (00000003) vpn multik forward in
5: - 2000000 (ffffffff89be6120) (00000003) vpn decrypt (vpn)
6: - 1fffffa (ffffffff89bbb0d0) (00000001) l2tp inbound (l2tp)
7: - 1fffff8 (ffffffff8a3d95d0) (00000001) Stateless verifications (in) (asm)
8: - 1fffff7 (ffffffff8a3d90f0) (00000001) fw multik misc proto forwarding
9: - 1fffff2 (ffffffff89a390e0) (00000003) vpn tagging inbound (tagging)
10: - 1fffff0 (ffffffff89bd6020) (00000003) vpn decrypt verify (vpn_ver)
11: - 1ff (ffffffff89f9b510) (00000001) NAC Packet Inbound (nac_tag)
12: 0 (ffffffff8a4c88d0) (00000001) fw VM inbound (fw)
13: 1 (ffffffff89bdb750) (00000003) vpn policy inbound (vpn_pol)
14: 2 (ffffffff8a3dbc60) (00000001) fw SCV inbound (scv)
15: 3 (ffffffff89bd3990) (00000003) vpn before offload (vpn_in)
16: 5 (ffffffff8a032830) (00000003) fw offload inbound (offload_in)
17: 10 (ffffffff8a4ba610) (00000001) fw post VM inbound (post_vm)
18: 100000 (ffffffff8a470f20) (00000001) fw accounting inbound (acct)
19: 7f730000 (ffffffff896bb4f0) (00000001) passive streaming (in) (pass_str)
20: 7f750000 (ffffffff8a20fdc0) (00000001) TCP streaming (in) (cpas)
21: 7f800000 (ffffffff8a3db7c0) (ffffffff) IP Options Restore (in) (ipopt_res)
22: 7fb00000 (ffffffff898f5bd0) (00000001) Cluster Late Correction (ha_for)
out chain (20):
0: -7f800000 (ffffffff8a3db810) (ffffffff) IP Options Strip (out) (ipopt_strip)
1: -78000000 (ffffffff89bda850) (00000003) vpn multik forward out
2: - 1ffffff (ffffffff89bce5c0) (00000003) vpn nat outbound (vpn_nat)
3: - 1fffff0 (ffffffff8a206e50) (00000001) TCP streaming (out) (cpas)
4: - 1ffff50 (ffffffff896bb4f0) (00000001) passive streaming (out) (pass_str)
5: - 1ff0000 (ffffffff89a390e0) (00000003) vpn tagging outbound (tagging)
6: - 1f00000 (ffffffff8a3d95d0) (00000001) Stateless verifications (out) (asm)
7: - 1ff (ffffffff89f40400) (00000001) NAC Packet Outbound (nac_tag)
8: 0 (ffffffff8a4c88d0) (00000001) fw VM outbound (fw)
9: 10 (ffffffff8a4ba610) (00000001) fw post VM outbound (post_vm)
10: 2000000 (ffffffff89bd1330) (00000003) vpn policy outbound (vpn_pol)
11: 1ffffff0 (ffffffff89bb98b0) (00000001) l2tp outbound (l2tp)
12: 20000000 (ffffffff89be15a0) (00000003) vpn encrypt (vpn)
13: 60000000 (ffffffff89bb9170) (00000001) tcpt outbound (tcp_tun)
14: 7f000000 (ffffffff8a470f20) (00000001) fw accounting outbound (acct)
15: 7f700000 (ffffffff8a2077f0) (00000001) TCP streaming post VM (cpas)
16: 7f800000 (ffffffff8a3db7c0) (ffffffff) IP Options Restore (out) (ipopt_res)
17: 7f850000 (ffffffff898f4e10) (00000001) Cluster Local Correction (ccl_out)
18: 7f900000 (0000000000000000) (00000000) SecureXL outbound (sxl_out)
19: 7fa00000 (0000000000000000) (00000000) SecureXL deliver (sxl_deliver)
monitor: monitoring (control-C to stop)
[vs_0][fw_4] 2Aug2020 0:16:09.083304 bond2.4:id2 (tcpt inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083309 bond2.4:id3 (IP Options Strip (in))[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083310 bond2.4:id4 (vpn multik forward in)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083314 bond2.4:id5 (vpn decrypt)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083316 bond2.4:iD6 (l2tp inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083317 bond2.4:iD7 (Stateless verifications (in))[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083319 bond2.4:iD8 (fw multik misc proto forwarding)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083321 bond2.4:iD9 (vpn tagging inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083328 bond2.4:iD10 (vpn decrypt verify)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083329 bond2.4:iD11 (NAC Packet Inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083330 bond2.4:iD12 (fw VM inbound )[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083663 bond2.4:ID13 (vpn policy inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083666 bond2.4:ID14 (fw SCV inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083668 bond2.4:ID15 (vpn before offload)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083669 bond2.4:ID16 (fw offload inbound)[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67
[vs_0][fw_4] 2Aug2020 0:16:09.083675 bond2.4:ID17 (fw post VM inbound )[337]: 192.168.141.220 -> 10.150.50.1 (UDP) len=337 id=26608
UDP: 67 -> 67

 

If I edit the default objects 'dhcp-request' and 'dhcp-reply' to remove the 'Match' strings, as shown here, it breaks DHCP relaying altogether:

dhcp_relay_edit_default_objects.png

 

I presume this is a bug?

 

Regards

David Herselman

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