![]() The minimum value is 1.īut not sure of the details of how pfsense uses dhclient, or if these are valid options for freebsd? This option specifies the default TTL that the client should use when sending TCP segments. This option specifies the default time-to-live that the client should use on outgoing datagrams. Hmmm, I believe those can be set with dhclient options Is there any way of changing the default TTL-value of DHCP-requests from the WAN interface? ![]() TTL WIRESHARK IP PCD-link or a PC with Windows gets a DHCP response without any problems (don't even need to shutdown the bridged modem, nor clone any mac's), while pfSense tries and tries no matter what I do, but never gets response) - I believe this might be caused by the low TTL-value of the requests. TTL WIRESHARK IP MACI've tried to clone the D-link's MAC (all the easy tryouts and suggestions from reading several forumposts) etc etc. (Fyi, I've tried shutting down the bridged modem for 10 minutes, before trying DHCP. The only reason I can think of is TTL-value and the possability that there might be more than 16 hops to the DHCP, as D-link sends it's requests with a TTL-value of 128, while pfSense has TTL-value of 16.and the latter never gets through. Connecting the pfSense behind the D-link, results in an a DHCP response without problems. My D-link router has no issues getting an DHCP-request from my ISP, while my pfSense-box has…. ![]() Depending on how their network is built, it might be more than 16 hops to this server, and in that scenario there will never be a response, since the requests never hit the server. When connecting to an ISP bridged modem, it is my understanding that DHCP requests are sent all the way to the ISP's DHCP-server, located somewhere on their internal network. If you know only the IP address of a remote system, you can use the Ping command to get the name of OS.I've noticed that the WAN interface (em0) sends out DHCP-requests with a TTL-value of 16 (Wireshark). However, it will give an idea of the underlying operating system in a remote system. This method may not be accurate all the time. The following table shows the default Initial TTL values of various operating systems and devices. ![]() The default TTL value for Windows OS is 128. Sample output from my Fedora desktop: PING localhost(localhost (::1)) 56 data bytesĦ4 bytes from localhost (::1): icmp_seq=1 ttl=64 time=0.063 msĦ4 bytes from localhost (::1): icmp_seq=2 ttl=64 time=0.057 msĦ4 bytes from localhost (::1): icmp_seq=3 ttl=64 time=0.070 msĦ4 bytes from localhost (::1): icmp_seq=4 ttl=64 time=0.067 msĦ4 bytes from localhost (::1): icmp_seq=5 ttl=64 time=0.056 msĥ packets transmitted, 5 received, 0% packet loss, time 4096ms To view the TTL value of a Linux/Windows host, simply ping the host from itself or from other systems on the network: Ping command comes pre-installed in most operating systems. TTL, stands for Time to live, is a timer value included in packets sent over TCP/IP-based networks that tells the recipients how long to hold or use the packet or any of its included data before expiring and discarding the packet or data.Īnd the Ping command is used to check the connectivity and reachability of system or device on local area network or wide area network. Detect remote host's operating system with TTL value You can view the complete list of TTL values for different operating systems and devices at the end. ![]()
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