Troubleshooting Network Connectivity

The following list covers nearly every cause of outbound connectivty failure in common usage scenarios. Each test assumes the items above it have been checked.

WAN Interface

  • Check that the WAN IP address is correct (Interfaces > WAN)

    • Using the wrong address could cause a failure of the ISP to deliver traffic to/from the firewall, among other issues
  • Check that the WAN IP address has the correct subnet mask (Interfaces > WAN)

    • An improper subnet mask such as /1 could cause connectivity issues to large portions of the Internet, using /32 for a mask can prevent the gateway from being found/used
  • Check that WAN has a gateway and that the gateway IP is correct (Interfaces > WAN)

    • This will interfere with automatic outbound NAT and route-to/reply-to handling
  • Check that the WAN gateway is set as default (System > Routing)

    • Without a default gateway traffic has no exit path
  • Check that the WAN gateway shows Online (Status > Gateways)

    • If it is not, verify the WAN settings and gateway settings, or use an alternate monitor IP
  • Verify that the defined WAN gateway is actually the default (Diagnostics > Routes)

    • Some other source such as a VPN may have changed the default gateway

LAN Interface

  • Check that the LAN IP address is correct (Interfaces > LAN)

    • Using an invalid IP address (e.g. .0 or .255 in a /24) will cause problems reaching addresses locally and will not work properly.
  • Check that the LAN subnet mask is correct (Interfaces > LAN)

    • Using an incorrect subnet mask, such as /32, will prevent other hosts in LAN from finding the LAN to use as a gateway and vice versa
  • Check that LAN does NOT have a gateway set (Interfaces > LAN)

    • This will interfere with automatic outbound NAT
  • Check that LAN does NOT have “Block Private Networks” set (Interfaces > LAN)

    • Should be obvious
  • Check that LAN does NOT have “Block Bogon Networks” set (Interfaces > LAN)

    • See above

Firewall/Rules

  • Check the firewall log for blocked connections from the LAN (Status > System Logs, Firewall tab)

    • If blocks are observed, check the rule that blocked and adjust rules accordingly (Firewall > Rules, LAN tab)
  • Check that the LAN rule allows all protocols, or at least TCP and UDP ports for reaching DNS and HTTP/HTTPS, and allows ICMP for testing. (Firewall > Rules, LAN tab)

    • Not allowing UDP would make DNS fail, among other things. Similarly, on a DNS rule, using UDP only and not TCP/UDP will cause larger queries to fail.
    • Not allowing ICMP would cause ping to fail, but other protocols may work
    • Not allowing TCP would cause HTTP, HTTPS, and other protocols to fail.
  • Check that the LAN rule allows to a destination of any (Firewall > Rules, LAN tab)

    • Traffic going to the Internet will need an “any” destination. Using the wrong destination would not allow traffic to reach the Internet (e.g. “WAN net” which is only the subnet of the WAN interface, NOT the Internet.)
  • Check that the LAN rule does not have an improper gateway set (Firewall > Rules, LAN tab)

    • If it is set to leave by some other (possibly broken) non-WAN gateway it would cause the connections to fail

Outbound NAT

  • Check Outbound NAT, ensure it is set for Automatic Outbound NAT unless Manual is required (Firewall > NAT, Outbound tab)

    • Incorrect NAT settings will prevent traffic from reaching WAN
  • Check Manual Outbound NAT rules, if in use, to ensure that the source of local traffic is matched

    • Incorrect NAT settings will prevent traffic from reaching WAN

Diagnostic Tests

  • Check connectivity from the firewall itself: Try to ping 8.8.8.8 (Diagnostics > Ping)

    • If this does not work, ensure proper WAN settings, gateway, etc.
  • Check DNS: Try to lookup pfsense.org (Diagnostics > DNS Lookup)

    • If this does not work, fix/change the DNS servers on System > General
  • Test NAT: Try to ping 8.8.8.8 (Diagnostics > Ping) using LAN as the Source Address

    • If this fails but the other tests work, then the problem is likely Outbound NAT (See the WAN/LAN gateway checks above)

Client Tests

  • Test if the client can ping the LAN IP of the firewall

    • If this fails, check the LAN rules, client IP/subnet mask, LAN IP/subnet mask, etc.
  • Test if the client can ping the WAN IP of the firewall

    • If this fails, check the client’s subnet mask and gateway
  • Test if the client can ping the WAN Gateway IP of the firewall

    • If this fails, check the client’s subnet mask and gateway, and double check Outbound NAT on the firewall
  • Test if the client can ping an Internet host by IP address (e.g. 8.8.8.8)

    • If this fails, check the client’s subnet mask and gateway, and triple check Outbound NAT on the firewall
  • Test if the client can ping an Internet host by Host name (e.g. www.google.com)

    • If this fails, check the client’s DNS settings, and/or the DNS Forwarder on the firewall (Services > DNS Forwarder, Diagnostics > DNS Lookup)

Miscellaneous Additional Areas

  • If Captive Portal is enabled, temporarily disable it (Services > Captive Portal).

  • Check for packages such as Squid that might interfere, disable them if necessary

    • Improperly configured proxies would allow certain traffic such as ICMP ping to work but might prevent access to HTTP and/or HTTPS sites.