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mountd through a firewall?

DISCUSSION Robert Rati 2 participants 9 messages Feb 19, 2003 – Feb 20, 2003

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Robert Rati

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#0 lore raw

I post this question a few days ago, but go no response. I hope someone on the list can help with this issue or point me in another direction.

When I start rpc.mountd, I notice that it always registers 4 ports with portmapper. 2 TCP and 2 UDP, which corespond to two separate instances of mountd. When I run exportfs, I see that no file systems are being exported. If I export a file system, the only difference is exportfs shows a file system being exported. This will obviously cause a problem if I try to specify a port for rpc.mountd to run on as both instances of mountd try to use the same port and the tcp bind for the second instance fails. Why does rpc.mountd start two instances of mountd?

This issue comes from trying to allow an NFS export through a firewall.
Since mountd uses different ports each time it starts, it's nearly
impossible to pass it through a firewall. Does anyone have an alternate solution to this problem besides telling rpc.mountd to run on a specified port (as that isn't working as detailed above). I'm stuck using kernel 2.2.17, so I've been unable to check out the nfs-utils ability to handle specifying a port for mountd.

Rob

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#1 lore raw
Quoted 9 lines · Robert Rati

When I start rpc.mountd, I notice that it always registers 4 ports with portmapper. 2 TCP and 2 UDP, which corespond to two separate instances of mountd. When I run exportfs, I see that no file systems are being exported. If I export a file system, the only difference is exportfs shows a file system being exported. This will obviously cause a problem if I try to specify a port for rpc.mountd to run on as both instances of mountd try to use the same port and the tcp bind for the second instance fails. Why does rpc.mountd start two instances of mountd?

It doesn't, so you must be doing something very wrong on your system -- are you starting a second mountd or something?

This is my system:

$ ps ax |grep mountd
26351 ?        S      0:01 rpc.mountd
$ rpcinfo -p | grep mountd
    100005    1   udp   4112  mountd
    100005    1   tcp   3231  mountd
    100005    2   udp   4112  mountd
    100005    2   tcp   3231  mountd
    100005    3   udp   4112  mountd
    100005    3   tcp   3231  mountd

One process, six ports, no problem.

Ion

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#2 lore raw
Quoted 6 lines · Ion Badulescu
Quoted 1 line · Robert Rati

When I start rpc.mountd, I notice that it always registers 4 ports with portmapper. 2 TCP and 2 UDP, which corespond to two separate instances of mountd. When I run exportfs, I see that no file systems are being exported. If I export a file system, the only difference is exportfs shows a file system being exported. This will obviously cause a problem if I try to specify a port for rpc.mountd to run on as both instances of mountd try to use the same port and the tcp bind for the second instance fails. Why does rpc.mountd start two instances of mountd?

It doesn't, so you must be doing something very wrong on your system -- are you starting a second mountd or something?

Thanks for the reply.

Actually, I mispoke in my first statement, sorry. mountd isn't creating two instances on the system, but it's opening 4 ports from the same instance. I thought that maybe mountd was opening a pair of ports for each exported filesystem, but my /etc/exports is bare, exportfs shows no exported file systems, so why is mountd using 4 ports? Even if I share a directory, mountd is still using 4 ports.

Is there a way to control the port range mountd will use? If not, do you know the range mountd will use?

Rob

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#3 lore raw
Quoted 6 lines · Robert Rati

Actually, I mispoke in my first statement, sorry. mountd isn't creating two instances on the system, but it's opening 4 ports from the same instance. I thought that maybe mountd was opening a pair of ports for each exported filesystem, but my /etc/exports is bare, exportfs shows no exported file systems, so why is mountd using 4 ports? Even if I share a directory, mountd is still using 4 ports.

That's the expected behavior, yes.

Quoted 2 lines

Is there a way to control the port range mountd will use? If not, do you know the range mountd will use?

man rpc.mountd, look for "-p".

Ion

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#4 lore raw
Quoted 4 lines
Quoted 1 line

Is there a way to control the port range mountd will use? If not, do you know the range mountd will use?

man rpc.mountd, look for "-p".

I've tried using the -p option, but that causes mountd to try to open all 4 ports on the same port. For the two UDP ports that not a problem (although I don't think functionally it'd work too well), but the two TCP ports obviously will have a problem. When I run rpc.mountd -p 5000, I get this error:

mountd: Could not bind name to socket: Address already in use

pmap_dump shows this:

    100005    1   udp   5000  mountd
    100005    1   tcp   5000  mountd
    100005    2   udp   5000  mountd

However, mountd is not running on the system even though it has registered ports with portmapper. Can I specify a range of ports somehow? I tried rpc.mountd -p5000:5002, but that didn't change anything.

Rob

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#5 lore raw
Quoted 7 lines · Robert Rati

I've tried using the -p option, but that causes mountd to try to open all 4 ports on the same port. For the two UDP ports that not a problem (although I don't think functionally it'd work too well), but the two TCP ports obviously will have a problem. When I run rpc.mountd -p 5000, I get this error:

mountd: Could not bind name to socket: Address already in use

Then you have a broken mountd.. because it doesn't need to listen on multiple ports. You saw my rpcinfo output, even without -p it was only using 2 distinct ports.

I just tested the mountd from both nfs-utils 0.3.3 and 1.0.1, both work correctly with respect to -p.

Ion

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#6 lore raw
Quoted 8 lines
Quoted 3 lines

I've tried using the -p option, but that causes mountd to try to open all 4 ports on the same port. For the two UDP ports that not a problem (although I don't think functionally it'd work too well), but the two TCP ports obviously will have a problem. When I run rpc.mountd -p 5000, I get this error:

mountd: Could not bind name to socket: Address already in use

Then you have a broken mountd.. because it doesn't need to listen on multiple ports. You saw my rpcinfo output, even without -p it was only using 2 distinct ports.

I just tested the mountd from both nfs-utils 0.3.3 and 1.0.1, both work correctly with respect to -p.

rpc.mountd -version gives this info:

kmountd 1.4.7 (0.4.22)

and I don't have nfs-utils installed on the system. I'm stuck using kernel 2.2.17 and I had read you had to have a 2.4 kernel to use nfs-utils. Is that incorrect? Is this possibly a limitation of the version of mountd on the system?

Rob

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#7 lore raw
Quoted 3 lines · Robert Rati

rpc.mountd -version gives this info:

kmountd 1.4.7 (0.4.22)

Ancient history.

Quoted 4 lines

and I don't have nfs-utils installed on the system. I'm stuck using kernel 2.2.17 and I had read you had to have a 2.4 kernel to use nfs-utils. Is that incorrect? Is this possibly a limitation of the version of mountd on the system?

Incorrect, nfs-utils works with any 2.2 and newer kernel.

Ion

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#8 lore raw
Quoted 1 line
Quoted 1 line

and I don't have nfs-utils installed on the system. I'm stuck using kernel 2.2.17 and I had read you had to have a 2.4 kernel to use nfs-utils. Is that incorrect? Is this possibly a limitation of the version of mountd on the system?

I downloaded the latest nfs-utils package and everything works great. Thanks for your help.

Rob

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