mpd5.1 MTU problem

Thu Jul 17 02:38:15 UTC 2008

Hello,
I set up a PPPoE server on FreeBSD 7.0(amd64) with mpd 5.1 and it works 
fine for all clients except for my FreeBSD 7.0(i386) Notebook. 
Connecting has no problem and I get ip but all website can not be access 
even on PPPoE server itself(Apache installed), so can not ftp site.
    I've used mpd 5.1_1 and pppoe(built-in) as pppoe client but the 
problem was same - can not access http/ftp..., only icmp works. I think 
the problem is MTU then changed that but no effects. Now my configuration:

PPPoE Server:
startup:
        set netflow peer 127.0.0.1 1813
        set user admin xxxxx admin
        set user operator xxxxx operator
        set user user xxxxx user
        set console open

default:
        load pppoe_server

pppoe_server:

        create bundle template B
        set ippool add pool 10.0.0.100 10.0.0.200
        set iface enable netflow-in
        set iface enable netflow-out
        set iface enable ipacct
        set iface enable proxy-arp
        set iface mtu 1460 <-----------------------!
        set ipcp ranges 10.0.0.1/32 ippool pool
        set ipcp dns 172.18.30.125

        create link template common pppoe
        set link enable pap
        set link disable chap
        set link enable multilink
        set link action bundle B
        load radius

        create link template em0 common
        set link max-children 1000
        set pppoe iface em0
        set link enable incoming

radius:
        set radius server 127.0.0.1 xxxxxxxx 1812 1813
        set radius retries 3
        set radius timeout 3
        set radius me 127.0.0.1
        set auth max-logins 1
        set auth acct-update 300
        set auth enable radius-auth
        set auth enable radius-acct
        set radius enable message-authentic

PPPoE client:
startup:
        set user admin xxxxx admin
        set console open

default:
        load pppoe_client

pppoe_client:
        create bundle static B1
        set iface route default
        set ipcp ranges 0.0.0.0/0 0.0.0.0/0

        create link static L1 pppoe
        set link action bundle B1
        set auth authname xxxxxx
        set auth password xxxxxx
        set link max-redial 0
        set link keep-alive 10 60
        set pppoe iface em0
        set pppoe service ""
        open

After connected:

PPPoE server:
ng15: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 
0 mtu 1460
        inet 10.0.0.1 --> 10.0.0.115 netmask 0xffffffff

PPPoE client:
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 0 
mtu 1460
        inet 10.0.0.115 --> 10.0.0.1 netmask 0xffffffff

tcpdump output:

PPPoE server:
pppoe# tcpdump -i ng15 -ln host 10.0.0.1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ng15, link-type NULL (BSD loopback), capture size 96 bytes
10:08:44.469993 IP 10.0.0.115.60331 > 10.0.0.1.80: S 
2092758811:2092758811(0) win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 4639873 0>
10:08:44.470056 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:08:47.469997 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:08:53.469978 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:09:05.469918 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:09:44.972709 IP 10.0.0.115.60331 > 10.0.0.1.80: F 1:1(0) ack 1 win 
8272 <nop,nop,timestamp 4700375 1602770998>
10:09:44.972744 IP 10.0.0.1.80 > 10.0.0.115.60331: R 
687014729:687014729(0) win 0

PPPoE client:
r00t# tcpdump -i ng0 -ln host 10.0.0.1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ng0, link-type NULL (BSD loopback), capture size 96 bytes
10:12:06.792399 IP 10.0.0.115.60331 > 10.0.0.1.80: S 
2092758811:2092758811(0) win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 4639873 0>
10:12:06.793151 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:12:06.793178 IP 10.0.0.115.60331 > 10.0.0.1.80: . ack 1 win 8272 
<nop,nop,timestamp 4639873 1602770998>
10:12:09.793385 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:12:09.793414 IP 10.0.0.115.60331 > 10.0.0.1.80: . ack 1 win 8272 
<nop,nop,timestamp 4642874 1602770998>
10:12:15.793331 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:12:15.793358 IP 10.0.0.115.60331 > 10.0.0.1.80: . ack 1 win 8272 
<nop,nop,timestamp 4648874 1602770998>
10:12:27.793227 IP 10.0.0.1.80 > 10.0.0.115.60331: S 
687014728:687014728(0) ack 2092758812 win 65535 <mss 1420,nop,wscale 
3,sackOK,timestamp 1602770998 4639873>
10:12:27.793255 IP 10.0.0.115.60331 > 10.0.0.1.80: . ack 1 win 8272 
<nop,nop,timestamp 4660874 1602770998>
10:13:07.294273 IP 10.0.0.115.60331 > 10.0.0.1.80: F 1:1(0) ack 1 win 
8272 <nop,nop,timestamp 4700375 1602770998>
10:13:07.295358 IP 10.0.0.1.80 > 10.0.0.115.60331: R 
687014729:687014729(0) win 0

    As you can see, tcp/ack from client can not go through but tcp/syn, 
tcp/fin are fine.

What's the reason? I've used the same client to connect to ISP's ADSL 
and work fine so what I am sure is the server refused my tcp/ack. But why?

Thanks all.

BSD4LZX

!DSPAM:487eacd27993450375810!