[hylafax-users] configuring router to support hylafax data connection. [give up]

[Eric Smith <es@xxxxxxxxxxxx>]

(Thank Marthter)

It seems from tcpdump that its like chasing your shadow,
The port number appear totally arbitrary and increase with each
instance of sendfax.

extract:
19:28:42.720944 172.28.1.36.hylafax > a.62646: P 167:189(22) ack 67 win 5792 <nop,nop,timestamp 53547228 1958282> (DF) [tos 0x10]
19:28:42.745027 a.62646 > 172.28.1.36.hylafax: P 67:73(6) ack 189 win 5840 <nop,nop,timestamp 1958284 53547228> (DF) [tos 0x10]
19:28:42.775277 172.28.1.36.hylafax > a.62646: . ack 73 win 5792 <nop,nop,timestamp 53547234 1958284> (DF) [tos 0x10]
19:29:06.452720 172.28.1.36.hylafax > a.62585: P 1:58(57) ack 1 win 5792 <nop,nop,timestamp 53549602 1957688> (DF) [tos 0x10]
19:29:06.452932 172.28.1.36.hylafax > a.62585: F 58:58(0) ack 1 win 5792 <nop,nop,timestamp 53549602 1957688> (DF) [tos 0x10]
19:29:06.478270 a.62585 > 172.28.1.36.hylafax: R 964280316:964280316(0) win 0 (DF) [tos 0x10]
19:30:22.463720 a.62646 > 172.28.1.36.hylafax: F 73:73(0) ack 189 win 5840 <nop,nop,timestamp 1968256 53547234> (DF) [tos 0x10]
19:30:22.494225 172.28.1.36.hylafax > a.62646: . ack 74 win 5792 <nop,nop,timestamp 53557207 1968256> (DF) [tos 0x10]
19:30:23.306833 a.62663 > 172.28.1.36.hylafax: S 1243073762:1243073762(0) win 5840 <mss 1380,sackOK,timestamp 1968340 0,nop,wscale 0> (DF)
19:30:23.306852 172.28.1.36.hylafax > a.62663: S 3944313999:3944313999(0) ack 1243073763 win 5792 <mss 1460,sackOK,timestamp 53557288 1968340,nop,wscale 0> (DF)
19:30:23.331568 a.62663 > 172.28.1.36.hylafax: . ack 1 win 5840 <nop,nop,timestamp 1968342 53557288> (DF)
19:30:23.333359 172.28.1.36.hylafax > a.62663: P 1:56(55) ack 1 win 5792 <nop,nop,timestamp 53557290 1968342> (DF) [tos 0x10]
19:30:23.358427 a.62663 > 172.28.1.36.hylafax: . ack 56 win 5840 <nop,nop,timestamp 1968345 53557290> (DF) [tos 0x10]
19:30:23.361550 a.62663 > 172.28.1.36.hylafax: P 1:12(11) ack 56 win 5840 <nop,nop,timestamp 1968345 53557290> (DF) [tos 0x10]
19:30:23.361557 172.28.1.36.hylafax > a.62663: . ack 12 win 5792 <nop,nop,timestamp 53557293 1968345> (DF) [tos 0x10]

Dunno why things have to be so complicated.

Time to retire gracefully (for now) ...

Eric 
marthter said:
> Hi Eric,
> 
> The HylaFAX protocol is mostly just the same as FTP.  That (FTP) 
> normally uses port 21 for control and port 20 for data.  HylaFAX seems 
> to do the same with 4559 and 4558.  There is also the active versus 
> passive FTP question, which, as I understand it, affects whether the 
> client or the server starts up the second port communication, but does 
> not change the fact that the second port is needed.
> 
> I don't recall the details, and I have since changed my setup so I can't 
> check it, but I think the HylaFAX server connects back to the client 
> with a _source_ port of 4558 (to a ?high? port on the client) when the 
> data connection is needed.
> 
> I definitely remember having similar problems and changing the _client_ 
> firewall to allow packets with a _source_ port of 4558 fixed it.  
> (Actually disabling the entire client firewall fixed it too, but this 
> port 4558 change was the minimal change that I could find that still 
> fixed it :-)
> 
> (Note this is different from most firewall settings where you generally 
> want to open up a _destination_ port, like destination port 80 needs to 
> be open to serve http requests).
> 
> Your setup probably isn't the same as mine, so the exact same solution 
> may not work, but, at any rate, you probably want to include port 4558 
> in your tcpdump as you try to get to the bottom of this.
> 
> Good luck.
> 
> Martin
> 
> 
> Eric Smith wrote  on 11/04/04 01:11 PM:
> 
> >Hi I am trying to redirect all requests on port 4559 to the router on 
> >62.166.236.150 to local machine 192.168.1.2
> >
> >The latter is to support dialogue for hylafax.
> >hylafax         4559/tcp                        # HylaFAX client-server 
> >protocol (new)
> >
> >I have ssh working with the entry for port 22 and web access with port 80, 
> >but my entry for port 4559 still results in
> >"Cannot build data connection" error with hylafax (running sendfax on the 
> >localmachine).
> >
> >NetDSL>show port
> >
> >Port Mapping
> >
> >TCP 62.166.236.150 4559     192.168.1.2 4559 0
> >TCP 62.166.236.150 22     192.168.1.2 22 0
> >TCP 62.166.236.150 80     192.168.1.2 80 0
> >
> >Any help appreciated (of course).
> >
> >Thanks!
> >
> >
> >Eric Smith
> >
> >FWIW: tcpdump activity on port 4559 follows:
> >
> >15:36:12.435459 62.166.236.150.62547 > 172.28.1.36.hylafax: S 
> >3141087652:3141087652(0) win 5840 <mss 1380,sackOK,timestamp 205344 
> >0,nop,wscale 0> (DF)
> >15:36:12.435477 172.28.1.36.hylafax > 62.166.236.150.62547: S 
> >951102318:951102318(0) ack 3141087653 win 5792 <mss 1460,sackOK,timestamp 
> >43511088 205344,nop,wscale 0> (DF)
> >15:36:12.460068 62.166.236.150.62547 > 172.28.1.36.hylafax: . ack 1 win 
> >5840 <nop,nop,timestamp 205346 43511088> (DF)
> >15:36:12.462445 172.28.1.36.hylafax > 62.166.236.150.62547: P 1:56(55) ack 
> >1 win 5792 <nop,nop,timestamp 43511091 205346> (DF) [tos 0x10]
> >15:36:12.493548 62.166.236.150.62547 > 172.28.1.36.hylafax: . ack 56 win 
> >5840 <nop,nop,timestamp 205349 43511091> (DF) [tos 0x10]
> >15:36:12.496672 62.166.236.150.62547 > 172.28.1.36.hylafax: P 1:12(11) ack 
> >56 win 5840 <nop,nop,timestamp 205350 43511091> (DF) [tos 0x10]
> >15:36:12.496679 172.28.1.36.hylafax > 62.166.236.150.62547: . ack 12 win 
> >5792 <nop,nop,timestamp 43511094 205350> (DF) [tos 0x10]
> >15:36:12.497090 172.28.1.36.hylafax > 62.166.236.150.62547: P 56:82(26) 
> >ack 12 win 5792 <nop,nop,timestamp 43511094 205350> (DF) [tos 0x10]
> >15:36:12.561257 62.166.236.150.62547 > 172.28.1.36.hylafax: P 12:25(13) 
> >ack 82 win 5840 <nop,nop,timestamp 205356 43511094> (DF) [tos 0x10]
> >15:36:12.561426 172.28.1.36.hylafax > 62.166.236.150.62547: P 82:113(31) 
> >ack 25 win 5792 <nop,nop,timestamp 43511101 205356> (DF) [tos 0x10]
> >15:36:12.617349 62.166.236.150.62547 > 172.28.1.36.hylafax: P 25:33(8) ack 
> >113 win 5840 <nop,nop,timestamp 205362 43511101> (DF) [tos 0x10]
> >15:36:12.617500 172.28.1.36.hylafax > 62.166.236.150.62547: P 113:137(24) 
> >ack 33 win 5792 <nop,nop,timestamp 43511106 205362> (DF) [tos 0x10]
> >15:36:12.672440 62.166.236.150.62547 > 172.28.1.36.hylafax: P 33:58(25) 
> >ack 137 win 5840 <nop,nop,timestamp 205367 43511106> (DF) [tos 0x10]
> >15:36:12.672599 172.28.1.36.hylafax > 62.166.236.150.62547: P 137:167(30) 
> >ack 58 win 5792 <nop,nop,timestamp 43511112 205367> (DF) [tos 0x10]
> >15:36:12.723283 62.166.236.150.62547 > 172.28.1.36.hylafax: P 58:66(8) ack 
> >167 win 5840 <nop,nop,timestamp 205373 43511112> (DF) [tos 0x10]
> >15:36:12.723432 172.28.1.36.hylafax > 62.166.236.150.62547: P 167:189(22) 
> >ack 66 win 5792 <nop,nop,timestamp 43511117 205373> (DF) [tos 0x10]
> >15:36:12.776377 62.166.236.150.62547 > 172.28.1.36.hylafax: P 66:72(6) ack 
> >189 win 5840 <nop,nop,timestamp 205378 43511117> (DF) [tos 0x10]
> >15:36:12.809997 172.28.1.36.hylafax > 62.166.236.150.62547: . ack 72 win 
> >5792 <nop,nop,timestamp 43511126 205378> (DF) [tos 0x10]
> >
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-- 
Eric Smith

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