Topic: GRE read or PTY write failed

[Anonymous]

Hello,

Please help me with the following problem: I am using SME Server now for a while but last week I decided I needed to update my 5.1.2 machine to the latest stable release so upgraded to 6.0.1-01. We depend heavily on PPTP/VPN connections for offices to connect to our SAP system.

Never had any problems with PPTP, it has been running for a few years without any problems at all but after upgrading to 6.0.1 PPTP/VPN connections are dropping packets or even worse cannot be made at all. Most common error at the client side is error 619. When I inspect my messages log, the following error keeps popping up after every failed connection:

pptpd[3602]: GRE: read(fd=6,buffer=80559a0,len=8260) from network failed: status = -1 error = Protocol not available
pptpd[3602]: CTRL: GRE read or PTY write failed (gre,pty)=(6,5)

I search trough all the posts in the forum and found a few postings that did look very similar to what I had but never found a decent solution so far.

Is there anybody facing similar problems or better someone that solved it?

Please help!!

Regards,
Peter

[boringgit]

I had this problem.

Out of interest, I found that connecting using the admin account worked fine...

When looking at other posts trying to solve my problem I did get the idea that a fresh install was more likely to work than an upgrade.

Perhaps if you have a spare box lying around you could try this?

[Anonymous]

I upgraded starting from scratch.

Regards,
Peter

[Anonymous]

Strange...

Maybe it's nothing but I tried restarting masq and all over sudden it starts working again. PPTP is accepting connections again.

/etc/rc.d/init.d/masq restart

Can anyone explain this?

Regards,
Peter

[hameren]

Hello,

Recently I had some nasty problems with remote PPTP connections connecting to our SME server. Since I solved my problem I thought this information could become useful for someone else.

My problem was every time a user connected from one site to my SME server it worked fine, however when another user from the same remote site connected to my SME server al PPTP traffic suddenly broke down. Reconnecting the PPTP tunnel at the client site resulted often in a error: 619.

Meanwhile, errors popped up in my logs, saying:
pptpd[3602]: GRE: read(fd=6,buffer=80559a0,len=8260) from network failed: status = -1 error = Protocol not available
pptpd[3602]: CTRL: GRE read or PTY write failed (gre,pty)=(6,5)

I found out that the problem had something to do with GRE and NAT gateways. If you have a NAT gateway, such as a DSL router, or in this case SME Server acting as server and gateway that presents one IP address to the network on which the PPTP Server is contacted, then only one PPTP connection can be active at once. The PPTP Server will only accept one.

Attempting to start a second tunnel to another IP address may also fail if the NAT software cannot differentiate the two connections. This may cause the first connection to fail, or like in my case all connections to fail.

Diagnosis: PPTP servers will not allow a connection to start from the same IP address that they perceive an active connection on already

Succes,
Peter